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不同类型甜瓜种质SSR遗传多样性及耐冷性评价
徐小军1, 刘海英2, 梁长志2, 王吉明1, 张桂兰1, 杨路明2, 胡建斌2
0
(1.中国农业科学院郑州果树研究所;2.河南农业大学园艺学院)
摘要:
从国家西瓜甜瓜种质中期库(郑州)和美国农业部国家种质资源中心选取厚皮、薄皮和野生甜瓜种质共 191 份, 利用在甜瓜染色体上均匀分布的 43 个 SSR 标记鉴定其基因型,评价其遗传多样性,并利用 4℃恒温条件下种质幼苗的冷害指 数和低温处理前后的叶肉组织超微结构变化评价不同类型种质的耐冷性。结果显示,SSR 标记共检测到 366 个等位基因,平 均 8.512,平均观测杂合度和期望杂合度分别为 0.074 和 0.704,平均多态性信息含量为 0.668。UPGMA 法将所有种质聚为 4 个类群(I、II、III 和 IV),I 群仅有 2 份印度野生种质,II 群包含来自印度的 34 份野生和 15 份薄皮种质,III 群含有地理分布 广泛的 51 份厚皮和 1 份野生种质,IV 群由来自东亚的 75 份薄皮、7 份厚皮和 6 份野生种质组成。Bayesian 算法将所有种质 分为 3 个亚群(P1、P2 和 P3),主要对应厚皮、野生和薄皮 3 类种质。通过计算 3 类种质间的分化系数和雷氏距离,结果发 现厚皮种质与薄皮种质间的分化最大,野生种质与薄皮或厚皮种质间的分化相对较小,不同类型种质多样性水平表现为:野 生种质 > 厚皮种质 > 薄皮种质。3 类种质幼苗的冷害指数趋向正态分布,薄皮种质的耐冷性要优于野生和厚皮种质。叶肉 组织超微观察显示,薄皮种质‘蛤蟆酥 5’在低温处理前后的细胞超微结构变化不大,其耐冷性较强,而厚皮种质“凤凰”在低温 处理后,叶绿体大量解体,细胞超微结构遭到破坏,其耐冷性较弱。
关键词:  甜瓜  种质资源  遗传多样性  耐冷性  超微结构
DOI:10.13430/j.cnki.jpgr.20190729002
投稿时间:2019-07-29修订日期:2019-09-22
基金项目:国家自然科学基金项目(31872101);中国农业科学院科技创新工程(CAAS-ASTIP-2015-ZFRI);河南省高校科技创新人才支持计划(20HASTIT035)
Genetic Diversity Analysis of Melon Germplasms Using SSR markers and Tests for Chilling Tolerance
XU Xiao-jun1, LIU Hai-ying2, LIANG Chang-zhi2, WANG Ji-ming1, ZHANG Gui-lan1, YANG Lu-ming2, HU Jian-bin2
(1.Zhengzhou Fruit Research Institute, Chinese Academy of Agriculture Sciences;2.College of Horticulture, Henan Agricultural University)
Abstract:
In order to investigate the genetic diversity of melon accessions, of 191 melon accessions including thick-skinned, thin-skinned, and wild types, which were collected from the National Mid-term Genebank for Watermelon and Melon (Zhengzhou, China) and USDA-ARS GRIN database, were analyzed with 43 chromosomally-distributed SSR markers. Furthermore, chilling tolerance was evaluated using the chilling-injury indices of melon seedlings under the constant temperature 4 ℃ as well as the leaf-ultrastructure changes before and after the low-temperature treatment. Totally, 366 alleles were detected by the SSR markers, with an average of 8.512 alleles per marker. Mean of observed and expected heterozygosity were 0.074 and 0.704, respectively, while mean of the polymorphism information index was 0.668. The method of UPGMA clustered all the accessions into four groups (I, II, III,and IV). Group I had only two genetically diverse Indian accessions. Group II included 34 wild accessions and 15 think-skinned accessions, all of which were originated from India. Group III comprised of 51 thick-skinned accessions and one wild accessions, which were collected from a wide geographic distribution. The remained 75 thin-skinned accessions, 7 thick-skinned accessions and 6 wild accessions were clustered into group IV, most of which were from East Asia. Furthermore, the Bayesian algorithm assigned the whole accession panel into three subpopulations (P1, P2 and P3), mostly correlated to the three germplasm types, i.e., thick-skinned, wild, and thin-skinned accessions. The coefficient of differentiation and Nei’ genetic distance among the three germplasm types indicated the highest level of genetic differentiation (FST) between the thick-skinned and thin-skinned accessions, following by FST values between wild accessions and thick-skinned accessions or thin-skinned accessions. The rank of the diversity level among the germplasm types were: wild accessions > thick-skinned accessions > thin-skinned accessions. The chilling-injury indices of the three germplasm types tended to follow normal distribution; the chilling tolerance of thin-skinned accessions was largely superior to that of wild or thick-skinned accessions. Leaf ultrastructure showed a slight change observed with the seedlings of the thin-skinned accession ‘Hamasu5’, indicating a high level of chilling tolerance. In contrast, the thick-skinned accession ‘Fenghuang’ presented a heavy chloroplast destruction and an aggravated damage in cell ultrastructure, indicating a high sensitivity to chilling temperature.
Key words:  melon  germplasm resource  genetic diversity  chilling tolerance  ultrastructure

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