Identification of genetic loci for flag-leaf-related traits in wheat (Triticum aestivum L.) and their effects on grain yield

Abstract

Flag-leaf-related traits including length (FLL), width (FLW), area (FLA), thickness (FLT), and volume (FLV) of flag leaves are the most important determinants of plant architecture and yield in wheat. Understanding the genetic basis of these traits could accelerate the breeding of high yield wheat varieties. In this study, we constructed a doubled haploid (DH) population and analyzed flag-leaf-related traits in five experimental locations/years using the wheat 90K single-nucleotide polymorphism array. It’s worth noting that a novel method was used to measure FLT and FLV easily. Leaf thickness at two-thirds of the leaf length from tip to collar represented the average leaf thickness as measured with freehand sections and was used to calculate the leaf volume. In addition, flag-leaf-related traits showed positive correlations with yield related traits under two different water regimes. A total of 79 quantitative trait loci (QTL) controlling the five traits were detected among all chromosomes except 4D and 5A, explaining 3.09–14.52% of the phenotypic variation. Among them, 15 stable QTL were identified in more than three environments, including two major QTL for FLT, six for FLW, three for FLA, two for FLT and two for FLV. DH lines with positive alleles at both QTL regions had an average FLL (9.90%), FLW (32.87%), FLT (6.62%), FLA (18.47%), and FLV (20.87%) greater than lines with contrasting alleles. QFLT-2B, QFLV-2A, and QFLV-7D were co-located with yield-related traits. The 15 QTL were validated by tightly linked kompetitive allele specific PCR (KASP) markers in a recombinant inbred line (RIL) population derived from a different cross. QFLL-4A, QFLW-4B, QFLA-5D.1, QFLA-7A, QFLA-7D.1, QFLT-2B, QFLT-6A, QFLV-2A, and QFLV-7D are likely novel loci. These results provide a better understanding of the genetic basis underlying flag-leaf-related traits. Also, target regions for fine mapping and marker-assisted selection were identified and these will be valuable for breeding high yielding bread wheat.

Natural allelic variation confers diversity in the regulation of flag leaf traits in wheat

“… 27 , increasing FLW is an effective approach for FLA enhancement compared to FLL. Previous reports using association panels and biparental populations also documented high heritabilities and positive correlations among flag leaf morphological traits and grain yield parameters 21 suggesting FL size optimization as an appropriate breeding approach for increasing wheat yield potential 20 .…”

“…For rice, some QTLs for spikelet number per panicle ( Gn1a , Gn1b , and SPP1 ) were reported to be close to qFLL1 , associated with FLL 26 . Promising candidate genes linked with FL morphology traits were previously documented using double haploid (DH), recombinant Inbred Lines (RILs), or F2 populations 15 , 21 , 22 , 30 . For instance, TaFLW1 related to FLW was mapped on 5AL closely related to Fusarium head blight (FHB) resistance gene Fhb5 31 .…”

Deciphering key genomic regions controlling flag leaf size in wheat via integration of meta-QTL and in silico transcriptome assessment

“…Interestingly, 48 of the identified MQTLs contained a 95% genetic CI below 2 cM (Table S1). It is widely accepted that optimizing flag leaf morphology, including the leaf length, width and area are important determinants to increase yield in wheat [82,84,95,96]. Generally, leaf size is controlled by two main dimensions: leaf length and width which are sensitive to environmental factors [97,98].…”