Abstract
Key messageGWAS analysis for leaf blade area (LA) revealed intriguing genomic regions associated with putatively novel QTL and known plant stature-related phytohormone and sugar-related genes.Despite long-standing studies in the morpho-physiological characters of leaf blade area (LA) in cereal crops, advanced genetic studies to explore its natural variation are lacking. The importance of modifying LA in improving cereal grain yield and the genes controlling leaf traits have been well studied in rice but not in temperate cereals. To better understand the natural genetic variation of LA at four developmental stages, main culm LA was measured from 215 worldwide spring barleys including 92 photoperiod-sensitive accessions [PHOTOPERIOD RESPONSE LOCUS 1 (Ppd-H1)] and 123 accessions with reduced photoperiod sensitivity (ppd-H1) locus under controlled greenhouse conditions (long-day; 16/8 h; ~ 20/~ 16 °C day/night). The LA of Ppd-H1-carrying accessions was always smaller than in ppd-H1-carrying accessions. We found that nine SNPs from the Ppd-H1 gene were present in the collection of which marker 9 (M9; G/T in the CCT-domain) showed the most significant and consistent effect on LA at all studied developmental stages. Genome-wide association scans (GWAS) showed that the accessions carrying the ppd-H1 allele T/M9 (late heading) possessed more genetic variation in LA than the Ppd-H1 group carrying G/M9 (early heading). Several QTL with major effects on LA variation were found close to plant stature-related heading time, phytohormone- and sugar-related genes. The results provide evidence that natural variation of LA is an important source for improving grain yield, adaptation and canopy architecture of temperate cereals.
Highlights
Leaf blade area (LA) is considered as one of the major drivers of plant architecture that in turn influences the adaptations to environmental cues and grain yield. Donald (1968) and Jennings (1964) proposed a model for enhancing grain yield potential by modifying traits such as leaf blade area (LA) in cereals using an “ideotype” breeding
Phenotypic analysis for LA based on the nine photoperiod-sensitive accessions [PHOTOPERIOD RESPONSE LOCUS 1 (Ppd-H1) markers (M1–marker 9 (M9)) showed significant differences in LA between the alleles of each marker at the studied developmental stages (Fig. 1c)
The results clearly indicated that M9 had the highest effect (***P, 0.001) among the Ppd-H1-derived markers at all developmental stages (Fig. 1c)
Summary
Leaf blade area (LA) is considered as one of the major drivers of plant architecture that in turn influences the adaptations to environmental cues and grain yield. Donald (1968) and Jennings (1964) proposed a model for enhancing grain yield potential by modifying traits such as LA in cereals using an “ideotype” breeding. Leaf blade area (LA) is considered as one of the major drivers of plant architecture that in turn influences the adaptations to environmental cues and grain yield. LA has a direct impact on crop stature, growth and yield through photosynthesis (Chen et al 1995) which can be maximized by expanding photosynthetic-LA in rice, sorghum and wheat (Driever et al 2014; Jiang et al 2015; Kebrom and Mullet 2015). The leaf is the major photosynthetic organ that supplies assimilates for regulating plant stature, e.g. photosyntheticLA is tightly linked with sugar production that in turn regulates shoot branching in sorghum (Evers 2015; Kebrom and Mullet 2015). The position of individual leaves affects their contribution to grain yield, especially the flag leaf, which is considered as the main source of carbohydrate synthesis in barley (Tao 1999).
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