Genetic dissection of flag leaf morphology in wheat (Triticum aestivum L.) under diverse water regimes

Abstract

Background: Morphological traits related to flag leaves are determinant traits influencing plant architecture and yield potential in wheat (Triticum aestivum L.). However, little is known regarding their genetic controls under drought stress. One hundred and twenty F8-derived recombinant inbred lines from a cross between two common wheat cultivars Longjian 19 and Q9086 were developed to identify quantitative trait loci (QTLs) and to dissect the genetic bases underlying flag leaf width, length, area, length to width ratio and basal angle under drought stress and well-watered conditions consistent over four environments.

Results: A total of 55 additive and 51 pairs of epistatic QTLs were identified on all 21 chromosomes except 6D, among which additive loci were highly concentrated in a few of same or adjacent marker intervals in individual chromosomes. Two specific marker intervals of Xwmc694-Xwmc156 on chromosome 1B and Xbarc1072-Xwmc272 on chromosome 2B were co-located by additive QTLs for four tested traits. Twenty additive loci were repeatedly detected in more than two environments, suggestive of stable A-QTLs. A majority of QTLs involved significant additive and epistatic effects, as well as QTL × environment interactions (QEIs). Of these, 72.7 % of additive QEIs and 80 % of epistatic QEIs were related to drought stress with significant genetic effects decreasing phenotypic values. By contrast, additive and QEIs effects contributed more phenotypic variation than epistatic effects.

Conclusions: Flag leaf morphology in wheat was predominantly controlled by additive and QEIs effects, where more QEIs effects occurred in drought stress and depressed phenotypic performances. Several QTL clusters indicated tight linkage or pleiotropy in the inheritance of these traits. Twenty stable QTLs for flag leaf morphology are potentially useful for the genetic improvement of drought tolerance in wheat through QTL pyramiding.

Keywords: Drought stress; Flag leaf morphology; Genetic dissection; Quantitative trait Loci; Triticum aestivum.

Fig. 1

Chromosome locations of A-QTLs for traits related to flag leaf morphology of main shoots in wheat RIL population. ①, ②, ③, ④ and ⑤ showed A-QTLs identified in a specific environment for flag leaf length (FLL), flag leaf width (FLW), flag leaf length to width ratio (FLWR), flag leaf area (FLA) and basal angle of flag leaf (BAFL), respectively. ➊, ➋, ➌, ➍ and ➎ represented A-QTLs identified in two or more environments for FLL, FLW, FLWR, FLA and BAFL, respectively

Fig. 2

Genetic effects and phenotypic variation explained (PVE) by genetic components for traits related to flag leaf morphology of main shoots in wheat RIL population across four environments. A, AA, AE and AAE mean additive effect, epistatic effect, additive QTL × environment interaction effect and epistatic QTL × environment interaction effect, respectively; h ²(A), h ²(AA), h ²(AE) and h ²(AAE) represent phenotypic variation explained (PVE) by A, AA, AE and AAE, respectively. Different lowercase letters indicate significant differences (P < 0.05) between genetic components for each trait