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Flowing Rock
Innovation of New Determinate Inflorescence Germplasm via Hybridization between Brassica napus and Brassica carinata
Distant hybridization is an important approach in crop genetic breeding and germplasm creation. In this study,the F1 hybrids were produced by interspecific hybridization between B. napus(2n=38,AACC)and B. carinata(2n=34,BBCC),and they showed determinate inflorescence characteristic from B. carinata and the intermediate morphology of both parents. F1 hybrids showed the expected chromosomal composition(2n=36, ABCC)and eight B.carinata(referred B)chromosomes from by GISH analysis. Their pollen mother cell(PMCs) showed multiple chromosome pairing configuration at diakinesis of meiosis,with main segregation rate of 17: 19 at anaphase Ⅰ(AⅠ). A number of lagging chromosomes and chromosomal bridges appeared during AⅠ and A Ⅱ,which caused pollen abortion. By continuous backcross using its parental line Zhongshuang 11(B.napus), the BC5F1 lines with determinate inflorescence were obtained and they had similar morphology with Zhongshuang 11. Their somatic chromosomes(2n=38)showed normal programmed meiosis,and only minor B chromosome signals but whole chromosomes were detected by GISH analysis. By marker assisted detection using 46 pairs of B genome specific SSR primers,B genome specific bands are detectable in F1 hybrid and a few of BC5F1. This result indicated that the chromosomal segments of B.carinata were successfully introduced into B.napus L.Thus, a number lines with new determinate inflorescence will become useful in rapeseed breeding for new varieties suitable for mechanized operation.
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Flowing Rock
Investigation on Wild Fagopyrum cymosum Resources in Yunnan and Analysis of Genetic Diversity
Fagopyrum cymosum(Trevir.)Meisn.is a perennial herb of the family Polygonaceae,which has a very high medicinal value because its swollen stems are rich in flavonoids.Wild Fagopyrum cymosum(Trevir.) Meisn.is widely distributed in China,especially in southwestern areas such as Yunnan,Guizhou,Sichuan.Our research group conducted a 20-day study in Yunnan and collected wild Fagopyrum cymosum(Trevir.)Meisn. resources from 14 different regions in Lijiang,Dali and Kunming.There were some differences in the plant or fruit morphology of wild golden buckwheat in different regions,which may be related to the geographical environment and climatic conditions.The contents of total flavonoids,rutin and quercetin in the swollen stems of wild golden buckwheat were measured by spectrophotometry and high performance liquid chromatography(HPLC).Results showed that the flavonoid contents of the swollen stems from different regions were remarkably different.Using ITS and matK molecular markers,genetic diversity and genetic relationship analysis were carried out,and it was found that the classification had a significant relationship with regional altitude.
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Flowing Rock
Evaluation and Genome-wide Association Study (GWAS)of Seedling Thermotolerance in Cucumber Core Germplasm
To investigate the cucumber thermotolerance at seedling stage and identify heat-tolerant accessions,this study analyzed 86 cucumber core germplasm at three-mature-leaves seedlings stage under greenhouse conditions (temperature:50±4 ℃). Scoring for heat damage was conducted based on heat injury symptoms,and the heat injury index (HII)was deployed to evaluate the thermotolerance of cucumber at seedling stage. Taking advantage of the whole genome re-sequencing datasets,the genome-wide association study (GWAS)was employed to identify the genetic loci that associated to the thermotolerance. The significant differences in HII were detected among tested materials,while the coefficient of variation under two environmental conditions were 21.9% and 22.5% respectively. By deploying HII,86 cucumber germplasms were clustered into four groups:heatresistant,medium heat-resistant,medium heat-sensitive and heat-sensitive group. The preliminary GWAS analysis suggested seven loci,including gHII4.1、gHII5.1、gHII5.2、gHII6.1、gHII7.1、gHII4.2 and gHII6.2,which were associated to the heat resistance. Among them,two loci gHII4.1 and gHII4.2 on chromosome 4,were found to be mostly relevant,and 67 candidate genes within this region were found.
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