Genomic regions associated with grain yield and aspects of post-flowering drought tolerance in pearl millet across stress environments and tester background

Abstract

Yadav, R. S., Hash, C. T., Bidinger, F. R., Devos, K. M., Howarth, C. J. (2004). Genomic regions associated with grain yield and aspects of post-flowering drought tolerance in pearl millet across stress environments and tester background. Euphytica, 136 (3), 265-277. Sponsorship: DfID R7375A pearl millet mapping population from a cross between ICMB841 and 863B was studied for DNA polymorphism to construct a genetic linkage map, and to map genomic regions associated with grain and stover yield, and aspects of drought tolerance. To identify genomic regions associated with these traits, mapping population testcrosses of 79 F3 progenies were evaluated under post-flowering drought stress conditions over 2 years and in the background of two elite testers. A significant genotype ? drought stress treatment interaction was evident in the expression of grain and stover yield in drought environments and in the background of testers over the 2 years. As a result of this, genomic regions associated with grain and stover yield and the aspects of drought tolerance were also affected: some regions were more affected by the changes in the environments (i.e. severity and duration of drought stress) while others were commonly identified across the drought stress environments and tester background used. In most instances, both harvest index and panicle harvest index co-mapped with grain yield suggesting that increased drought tolerance and yield of pearl millet that mapped to these regions was achieved by increased partitioning of dry matter from stover to the grains. Drought stress treatments, years and testers interactions on genomic regions associated with grain and stover yield of pearl millet are discussed, particularly, in reference to genetic improvement of drought tolerance of this crop using marker-assisted selection.Peer reviewe

Simulating the Yield Impacts of Organ-Level Quantitative Trait Loci Associated With Drought Response in Maize: A “Gene-to-Phenotype” Modeling Approach

“…A major concern of plant breeders is that many putative drought tolerance QTL identified are likely to have limited utility in applied breeding because of their dependency on genetic background or their sensitivity to the environment (Chapman et al 2003;Campos et al 2004;Hammer et al 2004;Podlich et al 2004;Yadav et al 2004). Precautions were taken in this study to work with QTL that were stable across environments and that were, at least for some of them, confirmed in several genetic backgrounds (Reymond et al 2003;Sadok et al 2007;Welcker et al 2007).…”

Plant drought stress: effects, mechanisms and management

“…Drought stress in soybean reduced total seed yield and the branch seed yield (Frederick et al, 2001). In pearl millet (Pennisetum glaucum), co-mapping of the harvest index and panicle harvest index with grain yield revealed that greater drought tolerance was achieved by greater partitioning of dry matter from stover to grains (Yadav et al, 2004). …”

“…A major cause of this, though not the only one, was a reduction in assimilate flux to the developing ear below some threshold level necessary to sustain optimal grain growth (Yadav et al, 2004). Moisture deficit reduced cotton (Gossypium hirsutum) lint yield, although the timing, duration, severity and speed of development undoubtedly had pivotal roles in determining how the plant responded to moisture deficit.…”

Recent Advances in Marker-Assisted Selection for Drought Tolerance in Pearl Millet

“…Two mapping populations based on hybrid parental lines with known differential responses to terminal stress were created, genotyped and phenotyped under managed fi eld stress conditions (Yadav et al, 2002(Yadav et al, , 2004. Both exercises consistently detected a major putatitve QTL for grain yield under terminal drought stress conditions (and/or the ability to maintain grain yield under such stress conditions) on pearl millet linkage group 2 (LG2), along with a small number of minor QTLs for both grain and stover yield and their components, under stress, that were identifi ed in some but not all phenotyping environments.…”

“…In most but not all cases, the favorable allele was contributed by the drought tolerant parent of the mapping population. Analysis of co-mapping of QTLs for individual yield component traits and for grain yield under stress, suggested a genetic basis for the observed association between the ability to maintain grain yield under stress and the ability to maintain both panicle harvest index (primarily grain fi lling) and harvest index under terminal stress, as well as confi rming the benefi ts of drought escape achieved through early fl owering (Yadav et al, 2002(Yadav et al, , 2004. Our current research emphasis is on evaluation of the putative QTLs as selection criteria in the genetic improvement of drought tolerance.…”