2021, 22(4):873-880. DOI: 10.13430/j.cnki.jpgr20210120001
Abstract:China has abundant crop germplasm resources. At present, 340 crops and a total of 490,000 accessions have been conserved at the national conservation system. How to ensure the safe conservation of germplasm resources is the responsibility and mission of genebank managers. Since the Ninth Five-Year Plan, the National Crop Genebank of China has systematically studied the theories and technologies of the safe conservation of germplasm. For the first time, we proposed a theory for germplasm resources conservation, including both safety backup and the biological mechanism of conservation. The transition from platform (high viability) to the rapid reduction phase of the seed survival curve was defined as the critical node (CN). It was revealed that oxidative damage and mitochondrial damage disorder the metabolism in the CN. In addition to, there was demonstrated that regeneration threshold values is the CN according to that the accession was regenerated when its germination rate was lower than the CN, resulting in the loss of genetic integrity. Taking loss of viability and genetic integrity together, safe longevity of germplasm is the period from the beginning of storage to the time point when seed viability declined to the CN. We have made breakthroughs on the key techniques for seed viability monitoring, early warning of viability decline, regeneration and in vitro preservation. Based on the above research, we have created a technological system for the safe conservation of crop germplasm resource, which has been applied in Chinese genebanks. For avoiding the loss of germplasm resources due to the loss of vigor and genetic integrity in genebank, the technological system would prolong the safe longevity of accession, monitor and forecast the accession viability, recognize the accession which needs to be regenerated. Therefore, the technological system provides a reliable guarantee for the safe conservation of crop germplasm resources in China.
2021, 22(4):881-889. DOI: 10.13430/j.cnki.jpgr.20201121002
Abstract:Rice is one of the most important food crops in the world. Since this crop is moderately sensitive to salt stress, land salinization is therefore a factor that restricts the increase of global rice production. At present, most studies focus on the salt tolerance of rice at the seedling stage, whereas identification of salt-tolerant phenotypes during the reproductive growth period of rice is rarely conducted. Breeding for new varieties showing salt-tolerant in lifecycle and its application is one of the optimal ways to improve saline soil. In recent years, a large number of salt-tolerant QTLs in rice have been molecularly identified, and significant progress has been made in breeding of new varieties showing salt tolerant. This article reviews the latest research progress in genomics, epigenetics, proteomics and metabolomics on salt tolerance, and provides a reference for exploring the molecular mechanism of salt tolerance and breeding for salt-tolerant varieties in rice.
2021, 22(4):890-899. DOI: 10.13430/j.cnki.jpgr.20201103002
Abstract:Rice is one of the most important grain crops in China, and weeds in paddy fields are the main factors affecting the yield and quality of rice. With the increase of planting areas of direct-seeded rice and light and simplified cultivation, the application of various herbicides has become increasingly common, the application rates of the herbicides have gradually increased, and the problems of resistant weeds and high residues in paddy fields have become increasingly serious. Therefore, it is of great significance to accelerate the innovation and utilization of various herbicide-resistant rice germplasms. In this paper, the types and mechanisms of herbicides, the research progress on herbicide-resistant rice germplasm innovation and application in China are reviewed, with existing problems and possible development direction discussed.
2021, 22(4):900-909. DOI: 10.13430/j.cnki.jpgr.20201020001
Abstract:MicroRNA (miRNA) is a well-studied small non-coding single-stranded RNA molecules encoded by endogenous genes with a length of about 20-24 nucleotides. It plays a key role in plant organ formation, growth and development, maintenance of genomic integrity and responses to abiotic stress. Among them, the miRNA169 family is detected widely with levels of conservativation in plants, and these family members participat into the regulation of a kind of conserved transcription factor NF-YA at post-transcriptional level. They are known crucial role in root development, lateral organ formation, floral organ formation, stomatal formation and stress of plants. Here we reviewed the origin and evolutionary mechanism of the miRNA169 family and its involvement in plant growth and response to abiotic stresses (i.e. high salinity, drought, low temperature and heavy metals) as other stresses conditions. We wish to provide insight of future understanding the biological function of miRNA169 family members responding to various stresses.
2021, 22(4):910-920. DOI: 10.13430/j.cnki.jpgr.20201124001
Abstract:Flax (Linum usitatissimum L.) is an economic crop with multiple utilization value. The rich nutrients and active substances of flaxseed as well as high-quality fiber make flax more and more popular. Therefore, producing high-quality flax varieties has become the current breeding goal. Traditional breeding methods have the limitation of the long cycles and limited choices. With the development of molecular biology and molecular markers, the traditional breeding methods combined with molecular breeding have met the breeding requirements. This article reviews the advances made in the application of molecular markers in flax, construction of genetic linkage maps, quantitative trait loci positioning, resistance and fertility marker positioning and genome-wide association analysis. The current problems of molecular marker assisted breeding in flax are discussed to provide some references for flax breeding in the future.
2021, 22(4):921-929. DOI: 10.13430/j.cnki.jpgr.20200828002
Abstract:Dwarfing is an important agronomic trait in crops, which can reduce lodging, enhance stress resistance and increase yield. Brassinosteroid is an important new plant hormone that regulates plant height during plant growth and development. Mutations that cause a decrease in Brassinosteroid level or impair Brassinosteroid signaling will produce a dwarf phenotype. This article focuses on the mutated genes that induce the dwarf phenotype in each pathway. The discovery of these genes has expanded the germplasm and genetic basis of dwarf crop breeding, and provides a theoretical basis for the creation of dwarf germplasm resources and rapid breeding of new dwarf varieties.
2021, 22(4):930-938. DOI: 10.13430/j.cnki.jpgr.20210109001
Abstract:Abiotic stress seriously affects plants growth and crop yield. Plant AREB (ABA responsive element binding protein)/ABF(ABRE binding factors) transcription factors are a type of leucine zipper protein that specifically recognizes ABA-responsive element (ABRE). They are involved in regulating the expression of ABA-responsive genes and play a crucial role in the response to abiotic stress in plant.This article introduced the structural characteristics of ABF transcription factors, the identified cis-acting elements, regulatory modification pathway and their roles in response to abiotic stress. This review might contributes a theoretical foundation for the application of ABF transcription factors to breed excellent cultivars?with stress tolerances.
2021, 22(4):939-950. DOI: 10.13430/j.cnki.jpgr.20210120002
Abstract:Southern rice black-streaked dwarf disease(SRBSDD), which is transmitted by white-backed planthopper [Sogatella furcifera (Horváth)], has caused severe yield loss in epidemic years in rice production. However, the reports on large-scale screening of SRBSDD resistant resources remain rare. In this study, 2812 Cultivated Rice Germplasm were evaluated for SRBSDD resistance under field and greenhouse conditions. The results showed that only 0.46% of tested accessions were resistance,the disease resistance level of different geographical sources, different germplasm types and different subspecies types was not consistent; 99.54% of tested accessions were susceptible, including many widespread varieties that are deploying in farming practice. That implied a potential of the increasing incidence and degree of SRBSDD in China in future. Seven genotypes showed reliable moderate disease resistance in multiple rounds of selection, with an average disease incident ranged from 6.72% to 28.51%. Specifically, avariation on heading date, plant height, effect panicle per plant, panicle length, spikelets per panicle, spikelet fertility, 1000-grain weight, single plant yield and length/width ratio of grain was observed in those 7 genotypes. Thus, this study unlocked the diseased incidence of SRBSDD in Cultivated Rice Germplasm, which will provide reference for rice resistance breeding.
2021, 22(4):951-962. DOI: 10.13430/j.cnki.jpgr.20201218001
Abstract:Generation of new special rice varieties with particular inherited characteristics are one of the important targets in hybrid rice breeding. The selection and utilization of special rice germplasm resources derived from different regions and identification of their genotypes and analysis of their particular characteristics are of great significance for further promoting the genetic improvement. By using functional molecular markers InDel-E2, FMbadh2-E7, CAPSRa, CAPS-Ra, FMbadh2-E2, FMbadh2-E7A, FMbadh2-E7B, Ra-CAPS1 and Ra-CAPS2, the last 5 of which are newly designed in this study, combined with gene cloning and sequencing technology, we identified the fragrance genotypes of 32 high-quality fragrant rice materials and the black pericarp genotypes of 8 black rice varieties, respectively, from different regions. Of the 32 fragrant rice varieties, 28 were found to have the fragrance character derived from the known badh2 allele (badh2-E7), which was located on rice chromosome 8 and had an 8-bp deletion and three single nucleotide polymorphisms (SNPs) in exon 7, and which was non-functional for encoding betaine aldehyde dehydrogenase (BADH2), two varieties (Bancangxiangnuo and Baguixiang) were found to be heterozygotic with Badh2/badh2, and the other two (Xixiang and Lixiangzhan) were found to lack the mutation in the coding region of Badh2 including both exon 2 and exon 7, thus without their fragrance character being controlled by Badh2 alleles. In addition, we found that the black pericarp character of all 8 black rice varieties was controlled by the Ra/Pb gene on rice chromosome 4, which has a 2-bp (GT) deletion in exon 7. Moreover, we analyzed the genetic characteristics of Badh2 and Ra genes by developing a number of F2 populations, and found that the fragrance and black pericarp were controlled by a nuclear recessive gene and a nuclear dominant gene, respectively. In this study, the identification and genetic analysis of fragrance gene in 32 high-quality fragrant rice materials and black pericarp gene in 8 black rice varieties derived from the different regions have been made, which provides an important theoretical foundation for further breeding of fragrant hybrid rice and black hybrid rice with high quality and high yield by molecular marker-assisted selective breeding technology, as well as for improving the efficiency in breeding of special rice, and for making new breakthrough to the discovery of novel fragrance gene and black pericarp gene.
2021, 22(4):963-970. DOI: 10.13430/j.cnki.jpgr.20201224001
Abstract:Southwestern China is internationally recognized as the origin of Fagopyrum Mill.，and its complex geographical environment and diverse climate types breed abundant wild buckwheat resources. Due to the similar ecological environment and climate，there are also a large number of wild buckwheat in some northwestern regions，contributing to a famous ethnic plant resource group with regional characteristics，which is an important basis for modern buckwheat breeding in China. In order to find out the distribution status of wild buckwheat in China and rescue the collection of wild buckwheat germplasm resources，the national survey and collection of wild buckwheat resources has been carried out since 2016 and 1014 wild buckwheat germplasm resources were collected in 6 provinces（autonomous regions） containing 42 counties（cities，districts） of western China. The phenotypic identification was performed and the classification of Fagopyrum in China was revised. The results showed that our collection included 21 species of Fagopyrum Mill.，containing a new species Fagopyrum longistylum. There are abundant genetic diversity among different wild buckwheat species，and many rare wild buckwheat species have unique character variation or excellent quality. These rare germplasm resources contain valuable gene pool，which provides valuable material basis for the yield and quality improvement of buckwheat. This study is of great significance not only to promote the classification and evolution of buckwheat， but also in crop genetic breeding，high-quality gene exploration and plant resource protection.
2021, 22(4):971-978. DOI: 10.13430/j.cnki.jpgr.20210201004
Abstract:Ear rot is a serious disease of maize caused by fungus in the producing areas. Discover excellent resistant germplasm resources and breeding resistant varieties are the most economical and effective measures to control maize ear rot. In this study, the ear rot resistance of 324 maize germplasm against Fusarium graminearum was identified by the ear puncture injection method in Tongzhou and Xiaotangshan of Beijing. Correlation analysis showed that there was a positive correlation between resistance evaluations in the two environments. According to the comprehensive analysis, 9 inbred lines with high resistance were OQ603, Bai Huang-hun, PI 539921, Mo17, PI 406119, F321, X178, B09 and PHG39, respectively. At the same time, it was found that the resistance of 48 inbred lines was above rated R level (including HR and R) in both breeding site. According to the resistance distribution of maize germplasm in different group, P group showed strong resistance overall, followed by Iodent and X germplasm, while the resistance distribution trend was not obvious in other populations. The identification of these resistant materials enriched the germplasm resources of maize to ear rot in China, and provided important materials for disease resistance breeding and theoretical research.
2021, 22(4):979-988. DOI: 10.13430/j.cnki.jpgr.20201207003
Abstract:In order to enrich the genetic diversity of common wheat, an EMS (Ethyl Methane Sulfonate)-induced mutagenesis population using the elite variety Jimai 22 was produced and the phenotypic variation in M2 generation plants was analyzed. The seed quality-related traits in M8 mutants showing excellent agronomical performance were further investigated. The results showed that: (1) out of 22599 M2 mutant plants, 5002 showed visible phenotypic variations with a rate of 22.13%. The phenotypic variations on fertility, growth period, ear, awn, leaf, plant type, tiller, plant height, grain color were observed. These mutants with bigger spike, multiple tillers, short stem, single stem, increased grains, no wax, leaf degradation and sterility were detected. (2) In M8 mutagenized lines, the morphological variations on grain shape, grain length, fullness and grain color were found. The variation coefficient regarding to eight quality-related traits was calculated (maximum tensile resistance > tensile area > stability time > sedimentation value > hardness >protein content > wet gluten content > water absorption). Eight mutant lines showing improved performance (in relative to Jimai 22) had been identified. For example, four lines including 403-1, 403-2, 403-3 and 85-2 showed significant improvement on at least 3 characters. Collectively, these mutants provided germplasm resource valuable for wheat breeding and deciphering the gene function.
2021, 22(4):989-999. DOI: 10.13430/j.cnki.jpgr.20210204001
Abstract:To decipher the genetic interaction of the fiber yield with quality-related traits in high-quality cotton varieties and screen elite lines with higher fiber quality, several traits have been measured in F2 and F2:3 populations, derived from variety CCRI127 with elite fiber quality crossing with sGK line Zhong 156 with high yield. Statistical analysis showed a normal distribution in traits including boll weight, lint percentage, upper half mean fiber length, fiber strength, micronaire, elongation and fiber uniformity. The transgression separation in populations if compared to both parents suggested abundant genetic variations. The ratios over the super high parent were 61.38% and 69.5% for average length of upper part of fiber in F2 and F2:3, 42.12% and 61.00% for fiber strength, and 41.75% and 28.43% for boll weight. A significant positive correlation between the average length of the upper half and fiber strength, and a significant negative correlation between lint percentage and fiber quality traits, including the average length of the upper half and fiber strength were observed, implying antagonistic on fiber yield and fiber quality. Ten individuals with fiber strength higher than 38.0 cN?tex-1 in F2 and F2:3 generations were selected, showing more than 31.0 mm on the average length of the upper half. Collectively, this study provided elite materials for the quantitative trait locus (QTL) mapping for fiber yield and fiber quality, and molecular breeding by stacking multiple elite genes.
2021, 22(4):1000-1008. DOI: 10.13430/j.cnki.jpgr.20201222004
Abstract:With characteristics of few seeds and high content of effective components in the fruit, dwarf habit, and strong stress resistance, polyploid plants plays an important role in crop and fruit tree breeding. Sweet orange ‘Licheng’ is a high-quality variety bred independently in China, which produces fruits with mostly monoembryonic seeds and a few polyembryonic seeds. So far, there are no reports about the polyploidy of this variety and the heterozygosity of its monoembryonic seeds. In this study, the screening, and genetic identification and analysis of polyploidy were carried out using sweet orange ‘Licheng’ as material. Two triploid and one tetraploid plants were selected by flow cytometry and chromosome microscopy from seedlings grown from naturally produced monoembryo seeds. Through the analysis of polyploidy by InDel markers, it was confirmed that these polyploids were grown from sexual embryos, and the proportion of homozygous loci was high, which may be caused by second meiotic division restitution (SDR) and post-meiotic genome doubling (PMD). Polyembryonic/monoembryonic molecular marker (MITE-P2) analysis showed that the clear short fragments and fuzzy long bands obtained from the genomic DNA amplification of ‘Licheng’ may be related to its ability to produce polyembryonic seeds, while the clear short bands only, obtained from the genomic DNA amplification of the three polyploid progenies, may be due to their inability to produce polyembryonic seeds. This study indicated that the proportion of polyploids in the progeny of ‘Licheng’ was high, with sexual polyploids obtainable from the monoembryonic seeds of ‘Licheng’, and monoembryo tetraploids obtainable from the progeny of ‘Licheng’, which provides an important reference for breeding of polyploids and monoemnryonic tetraploids with ‘Licheng’ as the parent.
2021, 22(4):1009-1020. DOI: 10.13430/j.cnki.jpgr.20210126003
Abstract:In order to develop and utilize Amomum tsaoko rationally, we investigated its resources in 16 of the production areas in Yunnan and Guangxi in 2019. Based on the species distribution information, combined with the maximum entropy model and GIS, the most suitable production areas were identified, and 15 fruits and spike traits of 57 accessions were evaluated. The results of maximum entropy model showed that the geographical distribution range of A. tsaoko was within 99.1-112.8 °E, 20.5-30.4 °N, with 48.14×104 km2 of optimal areas, mainly distributed in Yunnan, Guizhou, Sichuan and western Guangxi. Among the climatic factors, precipitation in June, standard deviation of seasonal variation of temperature, seasonal variation coefficient of precipitation, annual mean temperature, solar radiation in October, and precipitation in the driest month have greater effects on the geographical distribution of the species. In the resource survey it was found that Yunnan was the main production area of A. tsaoko, including southeast, northwest and west of the province; the habitat difference among the production areas was large, resulting in a variety of A. tsaoko planting patterns:⑴ Alnus nepalensis forest+Amomum tsaoko; (2) Cunninghamia lanceolata forest+Amomum tsaoko; (3) Juglans regia forest,Camptotheca acuminata forest, or Toxicodendron vernicifluum forest+ Amomum tsaoko; (4) The mixed primeval forest + Amomum tsaoko. The phenotypic data analysis showed that the phenotypic variation patterns were rich, and the average variation coefficient of the 15 traits was 27.34%. Among all those traits, the variation coefficient of volatile oil yield was the largest (53.54%), and the variation coefficient of fruit width was the smallest (7.43%). The correlation analysis showed that there was a strong correlation between the fruit and spike characters. According to clustering analysis, the 57 resources were divided into seven groups, among which groups Ⅰ, Ⅲ and Ⅴ class contained those from various origin. The principal component analysis showed that the cumulative contribution rate of the first five principal components was 80.53%, which could explain most of the information of the characters. Based on the comprehensive characteristics, 18 outstanding accessions were selected, with from Gongshan County of Nujian Prefecture having the best fruit . The above research results provide a theoretical basis for revealing the geographical distribution characteristics of A. tsaoko, rational planning of planting areas and screening high-quality resources.
2021, 22(4):1021-1030. DOI: 10.13430/j.cnki.jpgr.20210208002
Abstract:In order to provide germplasm resource and technical reference for the innovation and efficient utilization of cannabis germplasm resources in China, this study analyzed phenotypic variations on 14 agronomic and quality related traits in 198 cannabis germplasm accessions collected from China, Morocco and European countries. The results showed that either domestic or exotic cannabis germplasm accessions represented relatively abundant genetic diversity, with variation coefficients on 14 traits ranged from 4.79%-64.45%. The highest variation coefficient was CBD content and the lowest was female flowering date, with an average value of 27.78%. The variation coefficient regarding to four cannabinoids (CBN, CBD, CBDA and CBDV) is all higher than 40.0%, suggesting better variability at quality traits. The CBD content was found to significantly positively correlate with the content of CBDA, CBDV and CBN; the CBDA content was significantly positively correlated with the CBN content; the plant height was significantly positively correlated with the stem diameter. The CBDA content was significantly correlated with multiple agronomic traits, such as plant height and stem diameter. Principal component analysis revealed six principal components with a cumulative contribution rate of 69.204%, indicating that six principal components are able to represent large proportion of these phenotypic variations. Cluster analysis suggested three groups, in which 69 accessions of the first group showed better perfermance in terms of cannabinoid content, plant height and stem diameter, and they might be further tested for obtaining elite parental lines in breeding.
2021, 22(4):1031-1041. DOI: 10.13430/j.cnki.jpgr.20210222002
Abstract:To understand the composition and diversity distribution of anthocyanins in purple-fleshed sweetpotato, 68 domestic and exotic purple-fleshed accessions were subjected for analyzing the contents of 68 anthocyanins in 6 categories using LC-MS. The results showed that in six categories of anthocyanins, cyanidin and peonidin had higher contents and wider distribution ranges, while pelargonidin had the lowest content and the narrowest overall distribution range. The significant positive correlation was detected between the total content of anthocyanins with the contents of cyanidin, peonidin and petunidin, respectively. Systematic cluster analysis showed that the 68 purple-flesh sweetpotato accessions were clustered into 6 groups, among which the contents of all 6 categories of anthocyanins were higher in group II and lower in group IV. Eight anthocyanins were detected in all purple-flesh sweetpotato varieties, whereas nine were detected in 43, 12, 12, 44, 48, 44, 47 and 47 varieties, respectively. Correlation analysis of the 68 anthocyanins showed that several anthocyanins in each category had equal contents or showed highly significant positive correlation. Collectively, this study evaluated the composition and diversity distribution of anthocyanins composition of purple-fleshed sweetpotato accessions, and identified three purple-fleshed sweetpotato varieties with high content of 6 categories of anthocyanins and 7 varieties with high content of single type of anthocyanin. These materials are valuable for the promotion of high-quality sweetpotato and the subsequent selection and breeding of high-quality varieties.
2021, 22(4):1042-1047. DOI: 10.13430/j.cnki.jpgr.2020122900
Abstract:The endosperm of the sorghum grain is either waxy or non-waxy. Traditional Chinese liquors such as ‘Moutai’ and ‘Wuliangye’ are brewed with waxy sorghum as main feedstock. It is of great significance to clarify the waxy phenotype with efficient approaches in breeding and marketing. There are several methods such as staining and cooking, available for clarifying the waxy sorghum and non-waxy sorghum. However, these methods due to the limitation of efficiency might restrict the breeding for elite waxy sorghum varieties. In this study, four improved or newly-developed methods including cutting, hot water gelatinization staining, cold water smashing-staining as well as field-applicable pollen staining are suggested. We believed that deployment of these four methods is able to improve the efficiency on identification. The application of the four methods in waxy sorghum breeding program and their applicability are further discussed.
2021, 22(4):1048-1053. DOI: 10.13430/j.cnki.jpgr.20210115003
Abstract:The southern region of Gansu province, including Tianshui city and Longnan city, is a hot and the first emergency area of Puccinia striiformis f.sp. tritici (Pst) in China. Stripe rust is the most destructive disease of wheat in this area. Deployment of resistant-conferring wheat varieties is the most economical, environmental-friendly and effective method. Five wheat germplasm accessions including Guinong 19, Guinong 21, Guinong 22, Guinong 29 and Guinong 775 were derived from Guizhou university. Since 1994, these accessions have been widely used as parental lines in breeding for stripe rust resistance wheat cultivars in this area. We have conducted a long-term experiment during 1999-2020, in order to test for resistance to stripe rust at the seedling and adult stage both under greenhouse and field conditions. Three lines Guinong 19, Guinong 21, Guinong 22 have become susceptible by infection with Pst isolate CYR34, which was the ranking first popular race in Gansu province since 2015. Two accessions Guinong 29 and Guinong 775 remain to be resistant to CYR34 , and both are valuable in wheat breeding in southern region of Gansu province in future.
2021, 22(4):1054-1067. DOI: 10.13430/j.cnki.jpgr.20201208002
Abstract:Plant height is an important agronomic trait that affects wheat yield. To identify new genetic loci that are significantly associated to plant height, the genome-wide association study (GWAS) was conducted using 152 newly introduced synthetic wheat lines from International Maize and Wheat Improvement Center (CIMMYT). This population was subjected for measuring plant height at three environments and genotyping using 55K single nucleotide polymorphism (SNP) chip. The plant height was observed with a a normal distribution in synthetic genotypes, with the mean value of 97.9 cm, which was higher than that of modern cultivars (70.5 cm) but lower than that of local landraces (114.8 cm) in Huanghuai zone. Analysis of variance showed significant differences in the plant height of synthetic wheat in genotype, environment and interaction between environment and genotype. 37916 markers were qualified using filtering parameters to be polymorphic including 14404, 14566 and 8946 SNPs on the A, B and D sub-genome respectively. Population structure analysis of 152 synthetic wheat lines suggested three groups. GWAS using the mixed liner model (MLM) on the best linear unbiased prediction values (BLUP) revealed 24 significant SNPs (P≤0.0001), which were found on chromosomes 1A, 3B, 4A, 4B, 4D, 5A, 5B, 6A, 6D and 7B, each explaining12.33%-20.1% of the phenotypic variation. The annotation in a physical interval of 3 Mb querying significant SNPs suggested a total of 669 genes, among which 131 genes were found highly expressed in wheat stems or leaves (TPM≥5) in public transcriptome data. According to the functional annotation of wheat gene models and rice gene homologs, we speculated that five genes were possibly involved in plant height development. Since these significant loci did not overlap with previously reported QTLs, they may represent new genetic loci in controlling plant height. Collectively, these results provided new germplasm and selection markers in order to improve plant height in wheat.
2021, 22(4):1068-1080. DOI: 10.13430/j.cnki.jpgr.20201203001
Abstract:A no-pollen male sterile mutant tip2-zh was isolated from the EMS-soaked?progeny?of Zhonghui 8015 in this study. No significant difference in agronomic traits such as plant height, tiller number, tiller angle and heading date was observed between the tip2-zh mutant and the wild type, whereas tip2-zh mutant showed thinner, slender and translucent anthers as well as no mature pollen grains in the anther locule. The semi-thin sections of anthers during different development stages showed that the tip2-zh exhibited abnormal meiosis vacuolated tapetum with delayed degradation, the meiocyte mother cell could not generate microspore cells and finally resulting in failure of pollen grains formation. SEM observation also found that the linear substances of the outer surface in the mutant anther such as wax and cutin were more concentrated, the inner wall of the mutant anther exhibits irregular stratified and the microspores were finally broken and degraded. Genetic analysis showed that the mutation of tip2-zh was controlled by a recessive single gene in a 27 kb interval flanked by JX21 and JX26 on chromosome 1. Sequencing analysis revealed a C-to-T substitution in the first exon of the bHLH transcription factor TIP2/bHLH142 (LOC_Os01g18870), which resulted in a stop codon and encoded for an early-maturity protein, thus causing the male sterility. The transcriptional analysis using qPCR suggested that the expression levels on a series of GMS genes were changed significantly in the tip2-zh mutant. Collectively, these results proved that the gene TIP2-ZH played an important role in many biological processes during rice anther development such as the lipid synthesis of anthers, tapetum degradation and pollen wall formation.
2021, 22(4):1081-1089. DOI: 10.13430/j.cnki.jpgr.20201223001
Abstract:Panicle apical abortion occurs frequently in rice production, which can affect grain number per panicle and when serious may lead to the reduction of grain yield. Although some rice panicle apical abortion genes such as PAA1, PAA2, and TUT1 have been identified, their underling molecular mechanism are still poorly understood. In this study, we report a gene mapping and cloning of a recessive PAA tutou3 mutant in rice. The mutant had shorter plant height during vegetative development stage and serious panicle apical abortion at the later stage of panicle development, which resulted in significantly reduced grain number per panicle, panicle length and 1000-grain weight. Genetic analysis demonstrated that the phenotype of tutou3 was determined by a single recessive gene. Using 856 individuals with serious panicle apical abortion in the F2 segregating population derived from tutou3 × IRAT129, TUTOU3 locus was mapped in a 29 kb interval flanked by markers A-2 and A-17 on chromosome 4 containing 3 putative open reading frames (ORFs). Sequence analysis revealed a single nucleotide substitution of C to A at the eighth exon of LOC_Os04g56160, a plasma membrane H+-ATPase encoding gene, in tutou3, resulting in an amino acid change from alanine to aspartic acid. qRT-PCR analysis showed that TUTOU3 gene was constitutively expressed in rice, and its expression level decreased in the mutants. The mRNA expression levels of OsVPE2 and OsVPE3, which induce programmed cell death of apical panicle, increased significantly in the degraded spikelets in tutou3. Further study of TUTOU3 gene will reveal the role of H+-ATPase in the growth and development of panicle apical cells and help to elucidate the mechanism of panicle apical abortion at the cellular level.
2021, 22(4):1090-1098. DOI: 10.13430/j.cnki.jpgr. 20201203002
Abstract:Awn in common wheat is one of the important spike organs and plays a critical role in photosynthesis, insect resistance, bird-preventing and yield formation. The genetic basis on its formation and development remains largely unclear. To identify novel genetic loci involved in awn development, a genome-wide association study (GWAS) was performed using a diversity panel of 206 wheat accessions from Huang Huaihai region based on a Wheat 90K SNP array. The results showed that SNPs associated with phenotypic variation were detected on chromosomes 1A, 2A, 2B, 5A and 7A. SNPs with the highest significance were mainly located on chromosome 5A. Moreover, the bulked segregant analysis (BSA) in a recombinant inbred line population were analyzed using Wheat 660K SNP array. Out of 500 polymorphic SNPs, 158 were found in the 696.6-706.6 Mb interval of chromosome 5A, where the previously reported B1 locus encoding for Tipped1 was resided on the gene annotation of Chinese Spring. Gained from the re-sequencing result of this gene in parental lines, the wheat awn may be associated with a 25-bp insertion/deletion polymorphism located at -346 bp and a linkage SNP at -284 bp in the promoter region. Collectively, this study provided information for understanding the genetic mechanism of wheat awn development and molecular breeding.
2021, 22(4):1099-1108. DOI: 10.13430/j.cnki.jpgr. 20210129001
Abstract:Leaf width is one of the key determinants of plant architecture, and optimal leaf width is important to improve the light energy utilization efficiency and the yield production in rice. Identification of the new leaf width mutant and elucidation of its function is of interest to reveal the regulation mechanism. This study reported the zhaiye1 (zy1) mutant, which showed narrow leaf, reduced plant height, shortened panicle, opened spikelets and narrow-thin grains if compared with wild type (WT). The narrow leaf phenotype in zy1 is resulted mainly from the decrease in the number of large veins and small veins. Segregation analysis in a F2 population suggested two independent loci modulating the narrow leaf phenotype, which were further allocated to the regions of 76kb on chromosome 11 and 150kb on chromosome 12, respectively. Tow candidate genes Os11g01130 and Os12g01120 are duplicate genes and encode for the OsWOX3A transcriptional activator. The fusion protein stacking ZY1 with a C’-terminal in-frame GFP was localized to the nucleus in rice protoplastsm, while ZY1 was phylogenetically clustered with the homolog of O. meyeriana. In zy1 mutant, the transcriptome analysis revealed abundant genes in multiple signaling pathways (e.g.auxin signaling pathway). Collectively, these results suggested that ZY1 was involved in the development of leaf width as well as the regulation of plant height, panicle type, glume shell and other traits.
2021, 22(4):1109-1119. DOI: 10.13430/j.cnki.jpgr.20210129002
Abstract:Using a set of 309 recombinant inbred lines of the spring wheat ‘Worrakatta’ × ‘Berkut’ grown with normal irrigation and under drought stress, respectively, as materials, the phenotypes of leaf area index (LAI) at flowering, filling and ripening stages, and the flag leaf chlorophyll content (CC) at heading, flowering and filling stages were identified. QTL mapping was carried out with wheat 50K SNP chip. The results showed that LAI and CC decreased significantly under drought stress compared with normal irrigation treatment. It was found that LAI and CC of the parents and RIL lines were significantly different with an obvious phenomenon of transgressive segregation at different growth stages with the two treatments. Two and one LAI-related QTLs were detected at flowering stage and ripening stage, respectively, which were located on chromosomes 5BS, 2BL and 1BL with normal irrigation. QLAI.xjau-5BS, QLAI.xjau-2BL.1 and QLAI.xjau-1BL explained 6.8%-8.2% of the phenotypic variation. CC-related QTL QCC.xjau-1DS was detected at both heading and flowering stages, which was located on 1DS chromosome, explaining 5.3%-5.8% of the phenotypic variation. One LAI-related QTL, QLAI.xjau-2BL.2, located on 2BL chromosome, was detected at ripening stage under drought stress, explaining 13.8% of the phenotypic variation. Seven candidate genes related to LAI and CC were screened from the QTLs found in the study, which included two genes related to F-box family proteins and one gene each related to MYB, GATA, abscisic acid receptor, BTB/POZ and WUS. These genes are involved in regulating crop growth and development and signal transduction, as well as in response to drought and other stresses. This study provides reference information for gene discovery and molecular breeding of leaf area index and chlorophyll content in wheat.
2021, 22(4):1120-1132. DOI: 10.13430/j.cnki.jpgr.20201230001
Abstract:Cultivated soybean originated from temperate regions of China, and has a long history of planting in the country, with rich genetic resources. In recent years, however, the high degree of dependance on imported soyabean is a serious potential threat to the food security in China. Therefore, it is crucial to breed high-yield and high-quality soybean varieties, for which the exploration of genes that regulate major yield-correlated agronomic traits such as plant height and bean size, and the analysis of their molecular mechanisms are highly significant. FRITFULL (FUL) genes belong to the MADS box transcription factor, which play important roles in flowering, growth, development, and fruit ripening of plants. By bioinformatics analysis we found six FUL genes in soybean, all of which had a conservative MADS-box and a relatively conservative K-Box domain, and were mainly expressed in the pod, indicating that the gene family might be able to regulate seed-related traits of soybean. Among them, only GmFUL3b gene was highly expressed in the leaves, indicating that its function might have been differentiated in the process of evolution. In addition, we found that the six FUL genes followed different evolutionary rules. In order to further study their biological functions, knockout mutant vectors of the six FUL genes were constructed by CRISPR/Cas9 technology. Positive clones were transformed into soybean hairy roots for test target verification, and five of them were successfully identified as effective targets. It provided an important theoretical basis for obtaining stable soybean mutant materials and analyzing the function of GmFUL family genes.
2021, 22(4):1133-1144. DOI: 10.13430/j.cnki.jpgr.20210118002
Abstract:Fiber length and strength are the two most important traits in fiber quality of upland cotton (Gossypium hirsutum L.), and the understanding of their genetic basis is significant for breeding cultivars with high-quality cotton. We performed the genome-wide association study (GWAS) for fiber length and strength of association analysis group which comprises 315 upland cotton accessions grown in five different environments, through the mixed linear model (MLM). The results showed the presence of some differences in the phenotypic values of fiber length and strength, of high generalized heritability, with the fiber length variation coefficient ranging from 3.97% to 8.44%, and the fiber strength variation coefficient ranging from 7.85% to 11.26%. The analysis of variance for fiber length and strength showed highly significant effects of the genotype, environment, and genotype-environment interaction (P<0.001). Cluster analysis and population structure analysis showed that the 315 accessions could be divided into 2 groups. A total of 5 SNPs significantly associated with fiber length and/or strength were detected by GWAS, among which the locus D12_57032285 was significantly associated with both the fiber length and strength. The three loci significantly associated with fiber length were located on chromosomes A05, D11, and D12, respectively, which could explain 8.05%, 12.47% and 8.79% of the phenotypic variation, the elite allele types being A05_15144433 (AA), D11_24483544 (TT) and D12_57032285 (CC). The three loci significantly associated with fiber strength were located on chromosomes A08, D09 and D12, respectively, which could explain 9.03%, 7.94% and 7.90% of the phenotypic variation, the elite allele types being A08_84604654 (TT), D09_43463271 (TT) and D12_57032285 (CC). Through the analysis of gene expression patterns of two sets of different transcriptome data, 30 candidate genes that might be related to fiber development were selected. Through GO enrichment analysis and KEGG metabolic pathway analysis, it was found that the candidate genes mainly involved proteins or protein complexes and selectively and non-covalently interact with adenosine 5'-triphosphate (ATP), and the metabolic pathway was mainly the ribosomal metabolic pathway. The results can provide a theoretical basis for molecular genetic improvement of cotton fiber quality traits.
2021, 22(4):1145-1156. DOI: 10.13430/j.cnki.jpgr.20201204002
Abstract:SQUAMOSA promoter binding protein-like(SPL)gene family, as a class of transcription factors present widely in plants, has been shown to play important biological roles in plant growth, development, signal transduction, physiological and biochemical processes. In this study, 26 SPL genes from the radish genome have been identified using bioinformatic approach, and they are designated RsSPL1-RsSPL26 according to their locations on eight chromosomes. The amino acids encoded by SPL genes are variable from 139 to 1021 aa, with the protein molecular weight ranged from 16,167.7 to 112,219.48 Da and an isoelectric point of 5.77 to 9.67. Radish SPL genes contain 2 to 11 exons. MicroRNA target prediction suggested that 12 RsSPL genes contained complementary sequence of miR156 and 11 RsSPL genes contained complementary sequence of miR157. The expression patterns of RsSPL genes in different tissues and development stages showed spatial and temporal differences, and the same subfamily members showed similar expression patterns. Thus, these results provided insights for the functional characterization of the SPL genes family in radish.
2021, 22(4):1157-1166. DOI: 10.13430/j.cnki.jpgr.20201212001
Abstract:TGA (TGACG motif binding factor) transcription factors are an important group of the bZIP transcription factor family, which have broad-spectrum resistance to plant pathogens. Rosa chinensis ‘Old Blush’ TGA family members were identified in this study, with their physicochemical properties, subcellular localization, evolutionary characteristics and expression patterns analyzed. Seven RcTGAs were identified, all containing the conserved domains of bZIP1 (cl21462) and DOG1 (pfam14144), with the amino acid size of 324 to 545 aa, the molecular weight of 36.68 to 60.17 KD, the isoelectric point of 5.52 to 8.96, and the secondary structure of mainly α-helix, all being hydrophilic proteins mainly located in the nucleus. TGAs from Rosa chinensis ‘Old Blush’, Arabidopsis thaliana, Fragaria vesca, Prunus persica, and Malus domestica were divided into six subgroups through evolutionary analysis. The qPCR test showed that the expression of RcTGA4 did not significantly change in the petals after being infected by Botrytis cinerea, and the expression of RcTGA6 decreased after the infection, whereas the expression of RcTGA1/2 increased significantly, and the expression of RcTGA3/5/7 increased first and decreased later, indicating that RcTGA1/2/3/5/7 may play an important role in the resistance to B. cinerea, and could be candidate disease-resistance gene for further research and functional analysis. After silencing the expression of RcTGA2 by VIGS, the lesion diameter in rose petals increased significantly 48 h after infection by B. cinerea, indicating that RcTGA2 may be closely related to the resistance of rose to B. cinerea.
2021, 22(4):1167-1174. DOI: 10.13430/j.cnki.jpgr.20210220001
Abstract:One inbred of maize Reid-Lan., and 6 inbreds of maize RLT (Reid-Lan. × Tuxpe?o) were selected for testing, with 5 representative inbreds derived from 5 different subgroups as testers. 35 hybrids obtained from crossing the 12 inbreds by using the NCII genetic mating design and grown in Guiyang and Dejiang of Guizhou Province were evaluated for their yield-related traits, and the 12 inbreds were evaluated by using the gene chip MaizeSNP50 containing 60,000 SNPs, in order to enhance the utilization potential of Tuxpe?o and to take advantage of the genetic prepotency of Reid-Lan. germplasm in breeding. The results showed that the inbred QB2539 derived from RLT had the highest GCA of 7.28, which was higher than that of QB662 derived from Reid-Lan. The genetic distance (GD) value between Reid-Lan. germplasm inbred QB662 and QR273 was 0.3689, and the GD value between Tuxpe?o germplasm inbred S122 and QR273 was 0.3554, whereas the GD value between RLT germplasm inbred QB2539 and QR273 was 0.3732. Hybrids from the combination of RLT and Suwan germplasm were the top three among all the 35 combinations in regard to yield, among which QB2539 × QR273 had the highest yield, with a 29.66% increase over the CK of Qiandan 16. These results revealed the potential of RLT germplasm for wide use in maize breeding, and would provide some new improved methods and material support for maize germplasm innovation.