Jian Ma

Flag leaf chlorophyll content of wheat: genetic dissection, candidate genes prediction and its relationship with other agronomic traits

Chlorophyll is the primary pigment responsible for capturing light energy and driving photosynthetic conversion. As the key photosynthetic organ during grain filling, the flag leaf plays a critical role in carbon assimilation, consequently, its chlorophyll content (FLC) represents a promising target for enhancing wheat yield and ensuring food security. Dissecting the genetic basis underlying FLC and elucidating its relationships with other agronomic traits are essential for accelerating molecular breeding aiming at improving photosynthetic efficiency and yield in wheat varieties. In this study, a major and environmentally stable quantitative trait locus (QTL) for FLC was detected using a population of 197 recombinant inbred lines (RILs). This QTL, designated QFLC.scwl-4B , was consistently mapped to chromosome arm 4BS across multiple environments, explaining 9.36%–31.82% of the phenotypic variance (PVE). The effect of QFLC.scwl-4B was further validated in an additional RIL population under diverse environmental conditions. Correlation and effect analyses revealed that QFLC.scwl-4B exhibits pleiotropic, leading to increased FLC, spikelet number per spike (SNS), and flag leaf thickness (FLT), alongside reduced productive tiller number (PTN). Furthermore, a putative candidate gene for QFLC.scwl-4B , TraesCS4B03G0098300 , was identified as an ortholog of gene in BBX family, which is known to repress chlorophyll degradation and senescence, and likely involved in chlorophyll synthesis. Further, the promoter region of TraesCS4B03G0098300 harbors a single nucleotide polymorphism (G/C) between the two parents. Collectively, these findings provide valuable QTL resources and candidate gene targets for marker-assisted selection in breeding programs aiming at developing wheat varieties with high photosynthetic efficiency and yield.

Genetic dissection and QTL validation of seedling root system architecture in Chinese wheat landraces

Novel loci for flag leaf thickness with breeding potential: genetic dissection and candidate genes prediction

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.

Genetic identification and characterization of chromosomal intervals related to flag leaf size in common wheat.

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.