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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #338977
Title: Quantitative trait loci associated with drought tolerance in brachypodium distachyon

Author
item JIANG, YIWEI - Purdue University
item WANG, XICHENG - Jiangxi Academy Of Agricultural Sciences
item YU, XIAOQING - Iowa State University
item ZHAO, XIONGWEI - Purdue University
item LUO, NA - South China Agricultural University
item PEI, ZHONGYOU - Tianjin Agricultural University
item LIU, HUIFEN - Tianjin Agricultural University
item Garvin, David

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2017
Publication Date: 5/17/2017
Citation: Jiang, Y., Wang, X., Yu, X., Zhao, X., Luo, N., Pei, Z., Liu, H., Garvin, D.F. 2017. Quantitative trait loci associated with drought tolerance in Brachypodium distachyon. Frontiers in Plant Science. 8(811):1-11. doi:10.3389/fpls.2017.00811.

Interpretive Summary: Water is a limiting resource for agricultural production, and is expected to become more limiting in the future. Thus, it is imperative to identify strategies to improve crop productivity under water-limiting conditions. In this study, the model grass Brachypodium distachyon, a close relative of human staple crops including wheat, was employed to genetically dissect different components of drought tolerance. A population of plants from a cross between two Brachypodium genotypes that differ in their ability to withstand drought was evaluated for multiple traits that are indicators of drought tolerance. Subsequently, molecular genetic analysis identified the chromosome locations of several genes controlling some of the variation in the drought tolerance-related traits. In one instance, evidence suggests that one gene simultaneously affects variation for multiple drought-related traits. A small number of genes in this chromosome region were identified as candidates that may control variation in these traits. Our results suggest that Brachypodium can be employed to dissect the genetic and molecular basis of drought tolerance, including isolating the specific genes involved. Knowledge gained from such experimentation in Brachypodium, when transferred to crops such as wheat, will result in crops better able to maintain their productivity under drought stress conditions. This will enhance global food security as access to water for agricultural purposes decreases, at the same that the human population continues to grow.

Technical Abstract: The temperate wild grass Brachypodium distachyon (Brachypodium) serves as model system for studying turf and forage grasses. Brachypodium collections show diverse responses to drought stress, but little is known about the genetic mechanisms of drought tolerance of this species. The objective of this study was to identify quantitative trait loci (QTLs) associated with drought tolerance traits in Brachypodium. We assessed leaf fresh weight (LFW), leaf dry weight (LDW), leaf water content (LWC), leaf wilting (WT), and chlorophyll fluorescence (Fv/Fm) under well-watered and drought conditions on a recombinant inbred line (RIL) population from two parents (Bd3-1 and Bd1-1) known to differ in their drought adaptation. A linkage map of the RIL population was constructed using 467 single nucleotide polymorphism (SNP) markers obtained from genotyping-by-sequencing. The Bd3-1/Bd1-1 map spanned 1618 cM and had an average distance of 3.5 cM between adjacent single nucleotide polymorphisms (SNPs). Twenty-six QTLs were identified on chromosomes 1, 2, and 3 in two experiments, with 14 of the QTLs under well-watered conditions and 12 QTLs under drought stress. In Experiment 1, a QTL located on chromosome 2 with a peak at 182 cM appeared to simultaneously control WT, LWC, and Fv/Fm under drought stress, accounting for 11% to 18.7% of the phenotypic variation. Allelic diversity of candidate genes DREM2B, MYB, and SPK underlying QTLs played a role in explaining natural variation of whole plant drought tolerance in Brachypodium. Co-localization of QTLs for multiple traits indicate their importance in controlling drought tolerance in Brachypodium.