Contribution of photosynthetic- and yield-related traits towards grain yield in wheat at the individual quantitative trait locus level

Abstract

Grain yield improvement in wheat (Triticum aestivum L) requires understanding of the genetic control of grain yield components and other related traits. In this study, a total of 82 and 314 quantitative trait loci (QTLs) were associated with grain yield and grain yield components after harvest and photosynthetic traits at the seedling, heading and grain filling stages from a recombinant inbred line population by normal and multivariate QTLs analysis, respectively. Sixty-one QTL clusters explained from 4.42% to 27.72% of phenotypic variances for 2-76 traits. A comparison between the normal and conditional QTL mapping found that grain yield showed significant genetic correlation with grain yield components and photosynthetic traits on five QTLs. In the genetic region between Xbarc99 and Xbarc169 on chromosome 1D, grain yield was entirely contributed by thousand kernel weight and harvest index. At the same region, harvest index was contributed by transpiration rate at seedling stage, intercellular CO 2 concentration, stomatal conductance, net photosynthetic rate and transpiration rate at heading stage; and intercellular CO 2 concentration, net photosynthetic rate and transpiration rate at grain filling stage, whereas thousand kernel weight was suppressed by a normal QTL for chlorophyll content at grain filling stage in this region. The direct comparison analyses between grain yield with photosynthetic traits showed similar genetic relationships in this region. Manipulation of genes found within these QTL clusters might improve important agronomic traits and grain yield.

Higher Photochemical Quenching and Better Maintenance of Carbon Dioxide Fixation Are Key Traits for Phosphorus Use Efficiency in the Wheat Breeding Line, RAC875

“…Maintaining the photosynthetic rate under low P compared to under adequate P at the later stage could contribute to greater grain yield in RAC875 under low P. This result is consistent with our previous finding where under low P, RAC875 was better in maintaining phosphorylated sugars necessary for the biosynthesis of sugars and starch . This result is similar to previous studies that showed that the grain yield was positively correlated with photosynthetic rate at heading and the grain filling stage in wheat (Yu et al, 2020), and at stages before flowering in sorghum (Peng et al, 1991).…”

“…Gas exchange such as photosynthetic rate can also be used to evaluate the photosynthetic potential of plants (Johnson and Murchie, 2011). For example, a recent study in wheat showed a positive correlation between grain yield and photosynthetic rate at the heading and grain filling stage (Yu et al, 2020). A similar result in wheat grown under well-watered conditions was also reported by Wasaya et al (2021).…”