Maulana Frank, Weerasooriya Dilooshi, Tesso Tesfaye
Department of Agronomy, Kansas State University, ManhattanKS, USA.
Front Plant Sci. 2017 May 9;8:756. doi: 10.3389/fpls.2017.00756. eCollection 2017.
Cold temperature is an important abiotic stress affecting sorghum production in temperate regions. It reduces seed germination, seedling emergence and seedling vigor thus limiting the production of the crop both temporally and spatially. The objectives of this study were (1) to assess early season cold temperature stress response of sorghum germplasm from cooler environments and identify sources of tolerance for use in breeding programs, (2) to determine population structure and marker-trait association among these germplasms for eventual development of marker tools for improving cold tolerance. A total of 136 sorghum accessions from cooler regions of the world were phenotyped for seedling growth characteristics under cold temperature imposed through early planting. The accessions were genotyped using 67 simple sequence repeats markers spanning all ten linkage groups of sorghum, of which 50 highly polymorphic markers were used in the analysis. Genetic diversity and population structure analyses sorted the population into four subpopulations. Several accessions distributed in all subpopulations showed either better or comparable level of tolerance to the standard cold tolerance source, Shan qui red. Association analysis between the markers and seedling traits identified markers 34, 88, and 319 as associated with seedling emergence, 211 and 304 with seedling dry weight, and 20 with seedling height. The markers were detected on chromosomes previously found to harbor QTLs associated with cold tolerance in sorghum. Once validated these may serve as genomic tools in marker-assisted breeding or for screening larger pool of genotypes to identify additional sources of cold tolerance.
低温是影响温带地区高粱产量的重要非生物胁迫。它会降低种子发芽率、幼苗出土率和幼苗活力，从而在时间和空间上限制作物产量。本研究的目的是：（1）评估来自较凉爽环境的高粱种质对早期低温胁迫的响应，并鉴定可用于育种计划的耐受性来源；（2）确定这些种质之间的群体结构和标记-性状关联，以便最终开发用于提高耐寒性的标记工具。通过早播施加低温，对来自世界较凉爽地区的136份高粱种质的幼苗生长特性进行了表型分析。使用覆盖高粱所有十个连锁群的67个简单序列重复标记对这些种质进行基因分型，其中50个高度多态性标记用于分析。遗传多样性和群体结构分析将群体分为四个亚群。分布在所有亚群中的几个种质对标准耐寒源“Shan qui red”表现出更好或相当的耐受性水平。标记与幼苗性状之间的关联分析确定标记34、88和319与幼苗出土相关，211和304与幼苗干重相关，20与幼苗高度相关。这些标记位于先前发现含有与高粱耐寒性相关QTL的染色体上。一旦得到验证，这些标记可作为基因组工具用于标记辅助育种或筛选更大的基因型库，以鉴定额外的耐寒性来源。
