National Research Centre on Plant Biotechnology, Indian Agricultural Research Institute, New Delhi, India.
Funct Integr Genomics. 2012 Aug;12(3):447-64. doi: 10.1007/s10142-012-0276-1. Epub 2012 Apr 5.
Drought is a major constraint to maintaining yield stability of wheat in rain fed and limited irrigation agro-ecosystems. Genetic improvement for drought tolerance in wheat has been difficult due to quantitative nature of the trait involving multiple genes with variable effects and lack of effective selection strategies employing molecular markers. Here, a framework molecular linkage map was constructed using 173 DNA markers randomly distributed over the 21 wheat chromosomes. Grain yield and other drought-responsive shoot and root traits were phenotyped for 2 years under drought stress and well-watered conditions on a mapping population of recombinant inbred lines (RILs) derived from a cross between drought-sensitive semidwarf variety "WL711" and drought-tolerant traditional variety "C306". Thirty-seven genomics region were identified for 10 drought-related traits at 18 different chromosomal locations but most of these showed small inconsistent effects. A consistent genomic region associated with drought susceptibility index (qDSI.4B.1) was mapped on the short arm of chromosome 4B, which also controlled grain yield per plant, harvest index, and root biomass under drought. Transcriptome profiling of the parents and two RIL bulks with extreme phenotypes revealed five genes underlying this genomic region that were differentially expressed between the parents as well as the two RIL bulks, suggesting that they are likely candidates for drought tolerance. Syntenic genomic regions of barley, rice, sorghum, and maize genomes were identified that also harbor genes for drought tolerance. Markers tightly linked to this genomic region in combination with other important regions on group 7 chromosomes may be used in marker-assisted breeding for drought tolerance in wheat.
干旱是限制雨养和有限灌溉农业生态系统中小麦产量稳定的主要因素。由于涉及多个具有不同效应的基因，且缺乏利用分子标记的有效选择策略，因此小麦耐旱性的遗传改良一直很困难。在这里，使用随机分布在 21 条小麦染色体上的 173 个 DNA 标记构建了一个框架分子连锁图谱。在一个由耐旱敏感半矮秆品种“WL711”和耐旱传统品种“C306”杂交衍生的重组自交系（RIL）群体上，在干旱胁迫和充分供水条件下，对两年的籽粒产量和其他干旱响应的地上部和根系性状进行了表型分析。在 18 个不同的染色体位置上，针对 10 个与干旱相关的性状鉴定出 37 个基因组区域，但大多数区域的效应较小且不一致。在 4B 染色体的短臂上，与干旱敏感指数（qDSI.4B.1）相关的一致基因组区域被定位到一个与耐旱性相关的区域，该区域还控制着植株的单株籽粒产量、收获指数和根生物量。对具有极端表型的亲本和两个 RIL 群体的转录组分析揭示了该基因组区域内的五个基因，这些基因在亲本和两个 RIL 群体之间存在差异表达，表明它们可能是耐旱性的候选基因。鉴定到了与该基因组区域紧密连锁的大麦、水稻、高粱和玉米基因组的同源基因组区域，这些区域也含有耐旱基因。与该基因组区域紧密连锁的标记以及第 7 染色体组上的其他重要区域的标记可能被用于小麦耐旱性的分子辅助育种。
