As a key morphological trait of flag leaves, flag leaf thickness (FLT) directly modulates light energy capture efficiency and per-unit-area photosynthetic capacity, and is thus identified as a critical regulator of wheat grain yield formation. Dissecting the genetic basis underlying FLT is of great significance for accelerating the molecular breeding of high-yield wheat varieties. In this study, two recombinant inbred line (RIL) populations were employed to map quantitative trait locus (QTL) for FLT across five independent environments. A total of 19 QTLs controlling FLT were identified in the two RIL populations. Among them, QFLT.suas-2CN-4B.2, QFLT.suas-2CN-6A, QFLT.suas-2SY-3B.2, and QFLT.suas-2SY-6A exhibited stable expression across multiple environments, and comparative analysis with previously reported QTLs indicated that all four loci are likely novel. Notably, QFLT.suas-2CN-6A and QFLT.suas-2SY-6A were co-localized within the same physical interval, suggesting they are likely the same locus. Candidate gene analysis for the co-localized locus QFLT.suas-2CN-6A and QFLT.suas-2SY-6A identified seven putative candidate genes highly expressed in wheat leaves, all of which encode chlorophyll a-b binding proteins that may participate in the regulation of FLT development. Furthermore, significant positive correlations between FLT and spikelet number per spike (SNS) were detected in both RIL populations. The favorable alleles of QFLT.suas-2CN-6A and QFLT.suas-2SY-6A significantly increased SNS by 3.21% and 3.31%, respectively. Collectively, these results deepen our understanding of the genetic basis underlying wheat FLT, and provide stable, valuable QTL resources and candidate gene targets for molecular marker-assisted breeding of high-yield wheat.
Jiajun Liu, Lei Tao, Nana Qin et al.· Frontiers in Plant Science· 0 citations
The flag leaf is a crucial component of the ideal plant architecture in wheat (Triticum aestivum L.), directly influencing photosynthetic efficiency and yield. This study utilized an F6 recombinant inbred line (RIL) population derived from a cross between the natural mutant msf, which possesses elongated and broad flag leaves, and the cultivar Chuannong 16 (CN16). A genetic linkage map constructed using a 16K SNP chip enabled the identification of 34 quantitative trait loci (QTL) for flag leaf length (FLL), flag leaf width (FLW), flag leaf area (FLA), and flag leaf length-to-width ratio (FLR). Notably, major QTL QFlw.sau-MC-1A for FLW and QFla.sau-MC-1A for FLA were co-localized on chromosome 1AS, explaining 9.26-19.47% and 9.70-17.53% of the phenotypic variation, respectively. The favorable alleles from the msf parent significantly increased FLL, FLW, and FLA. A Kompetitive Allele-Specific PCR (KASP) marker developed from a SNP within the QTL interval was used to successfully validate the major QTL in independent populations. Pleiotropic effects showed that this locus positively influenced spike length (SL) and seven spike-related traits, including fertile florets per spike (FFS), kernel weight per spike, total florets per spike, florets per spikelet, florets in the middle spikelet, fertile florets per spikelet, and kernel weight per spikelet, but negatively influenced effective tiller number (ETN), plant height (PH), and anthesis date (AD). Cell morphologic analysis indicated that the difference in flag leaf size between msf and CN16 may be attributable to combined differences in cell morphology and cell number. Based on these results, together with the functional annotation of candidate genes in the interval, three genes putatively controlling leaf development were predicted. These findings offer valuable insights for breeding wheat varieties with ideal plant architecture.
Yuxin Lan, Li Yin, Yuanjiang He et al.· Plant Science· 0 citations
