Associations of canopy leaf traits with SNP markers in durum wheat (Triticum turgidum L. durum (Desf.))

Abstract

The canopy leaves including the top three, i.e., the flag, the 2nd and 3rd from the top, are important for photosynthesis and grain yield of wheat. Molecular markers associated with traits of these leaves should be helpful for the high-yielding breeding. In this study, 1366 single nucleotide polymorphisms (SNP) markers covering the whole genome of durum wheat were used to genotype 150 cultivars collected from 46 countries and regions in the world. Leaf length, leaf width and chlorophyll content of the top three leaves were measured, respectively, in three consecutive years. Association analyses were performed on the leaf traits and SNP markers. A total of 120 SNP marker associations were detected on 13 of the 14 chromosomes. Among these markers, 83 were associated with the canopy leaf traits, 10 with 1000-grain weight, and 29 with kernel number per spike. This study is helpful for better understanding the potential and genetic basis of functional leaves, and facilitates pyramiding of the favorable alleles using marker assisted selection for ideal plant-type and high photosynthesis efficiency in durum wheat breeding.

Fig 1. Frequency distribution of the 15 examined canopy leaf traits and 1000-grain weight of durum wheat in three consecutive years.

P value of Shapiro–Wilk test for each year was shown, the hypothesis of normal distribution could be accepted when P > 0.05 (significant at P = 0.05), and the trend lines of the accepted normal distribution were shown. FLL, flag leaf length (cm); SLL, second leaf length (cm); TLL, third leaf length (cm); FLW, flag leaf width (cm); SLW, second leaf width (cm); TLW, third leaf width(cm); FLA, flag leaf area (cm²); SLA, second leaf area (cm²); TLA, third leaf area (cm²); FLCC, flag leaf chlorophyll content; SLCC, second leaf chlorophyll content; TLCC, third leaf chlorophyll content; TATL, total area of the top three leaves; ACTL, average chlorophyll content of the top three leaves; KGW, 1000-grain weight (g).

Fig 2. Chromosome bin map of plausible QTL anchored by SNP markers in durum wheat.

The relative interval length is indicated on the left of each chromosome and QTL are shown on the right.