Crop Physiology Laboratory, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, 502324, India.
Bharathidasan University, Tiruchirappalli, Tamilnadu, 620 024, India.
Theor Appl Genet. 2018 Jul;131(7):1509-1529. doi: 10.1007/s00122-018-3094-6. Epub 2018 Apr 21.
Four genetic regions associated with water use traits, measured at different levels of plant organization, and with agronomic traits were identified within a previously reported region for terminal water deficit adaptation on linkage group 2. Close linkages between these traits showed the value of phenotyping both for agronomic and secondary traits to better understand plant productive processes. Water saving traits are critical for water stress adaptation of pearl millet, whereas maximizing water use is key to the absence of stress. This research aimed at demonstrating the close relationship between traits measured at different levels of plant organization, some putatively involved in water stress adaptation, and those responsible for agronomic performance. A fine-mapping population of pearl millet, segregating for a previously identified quantitative trait locus (QTL) for adaptation to terminal drought stress on LG02, was phenotyped for traits at different levels of plant organization in different experimental environments (pot culture, high-throughput phenotyping platform, lysimeters, and field). The linkages among traits across the experimental systems were analysed using principal component analysis and QTL co-localization approach. Four regions within the LG02-QTL were found and revealed substantial co-mapping of water use and agronomic traits. These regions, identified across experimental systems, provided genetic evidence of the tight linkages between traits phenotyped at a lower level of plant organization and agronomic traits assessed in the field, therefore deepening our understanding of complex traits and then benefiting both geneticists and breeders. In short: (1) under no/mild stress conditions, increasing biomass and tiller production increased water use and eventually yield; (2) under severe stress conditions, water savings at vegetative stage, from lower plant vigour and fewer tillers in that population, led to more water available during grain filling, expression of stay-green phenotypes, and higher yield.
四个与水分利用特性相关的遗传区域，这些特性在不同的植物组织水平上进行测量，并与农艺性状相关联，在先前报道的与末端水分亏缺适应相关的连锁群 2 区域内被鉴定出来。这些性状之间的紧密连锁表明，对农艺和次生性状进行表型分析对于更好地理解植物生产过程具有重要价值。节水性状对珍珠粟适应水分胁迫至关重要，而最大限度地利用水分是避免胁迫的关键。本研究旨在证明在不同植物组织水平上测量的性状之间的密切关系，这些性状与一些假定参与水分胁迫适应的性状有关，与负责农艺表现的性状有关。一个珍珠粟的精细图谱群体，在 LG02 上分离出一个先前鉴定的适应末端干旱胁迫的数量性状位点 (QTL)，在不同的实验环境（盆栽、高通量表型平台、蒸渗仪和田间）中对不同水平的植物组织特性进行了表型分析。利用主成分分析和 QTL 共定位方法分析了实验系统中各性状之间的联系。在 LG02-QTL 内发现了四个区域，这些区域显示出水分利用和农艺性状的大量共定位。这些在不同实验系统中鉴定出来的区域提供了遗传证据，证明了在较低植物组织水平上表型的性状与在田间评估的农艺性状之间的紧密联系，从而加深了我们对复杂性状的理解，然后使遗传学家和培育者都受益。简而言之：（1）在无/轻度胁迫条件下，增加生物量和分蘖产量会增加水分利用，最终增加产量；（2）在严重胁迫条件下，该群体在营养生长阶段节省水分，由于植物活力降低，分蘖减少，在灌浆期有更多的水分可用，表现出绿色保持表型，产量更高。
