Abstract
Manipulation of genes involved in starch synthesis could significantly affect wheat grain weight and yield. The starch-branching enzyme (SBE) catalyzes the formation of branch points by cleaving the α-1,4 linkage in polyglucans and reattaching the chain via an α-1,6 linkage. Three types of SBE isoforms (SBEI, SBEII, and SBEIII) exist in higher plants, with the number of SBE isoforms being species-specific. In this study, the coding sequence of the wheat TaSBEIII gene was amplified. After the multiple sequence alignment of TaSBEIII genome from 20 accessions in a wheat diversity panel, one SNP was observed in TaSBEIII-A, which formed the allelic marker allele-T. Based on this SNP at 294 bp (C/T), a KASP molecular marker was developed to distinguish allelic variation among the wheat genotypes for thousand grain weight (TGW). The results were validated using 262 accessions of mini core collection (MCC) from China, 153 from Pakistan, 53 from CIMMYT, and 17 diploid and 18 tetraploid genotypes. Association analysis between TaSBEIII-A allelic variation and agronomic traits found that TaSBEIII-A was associated with TGW in mini core collection of China (MCC). The accessions possessing Allele-T had higher TGW than those possessing Allele-C; thus, Allele-T was a favorable allelic variation. By analyzing the frequency of the favorable allelic variation Allele-T in MCC, it increased from pre-1950 (25%) to the 1960s (45%) and increased continuously from 1960 to 1990 (80%). The results suggested that the KASP markers can be utilized in grain weight improvement, which ultimately improves wheat yield by marker-assisted selection in wheat breeding. The favorable allelic variation allele-T should be valuable in enhancing grain yield by improving the source and sink simultaneously. Furthermore, the newly developed KASP marker validated in different genetic backgrounds could be integrated into a breeding kit for screening high TGW wheat.
Highlights
Wheat is the staple food for ∼33% of the population across the globe (Su et al, 2011)
The level of polymorphism in wheat was 1 single nucleotide polymorphism (SNP)/540 bp based on the bioinformatic analysis of large wheat EST database of 12 accessions (Somers et al, 2003)
TaSBEIII CDS was sequenced in the 20 diverse cultivars of wheat and polymorphism was detected
Summary
Wheat is the staple food for ∼33% of the population across the globe (Su et al, 2011). According to a worldwide survey, food demand will increase by 40% in the post-2020 era due to the rapid increase in global population (Su et al, 2011; Wang et al, 2019). To ensure this food security issue, there is a need to develop high-yield varieties through advanced molecular breeding (Wang et al, 2019). Sink capacity is more important in wheat as compared to source so there is a need to explore the starch synthesis enzymes to accelerate the wheat yield through breeding (Hou et al, 2014). The metabolism process of different enzymes [ADP-glucose pyrophosphorylases, starch synthases, starch-branching enzymes (SBEs), and starch-debranching enzymes] helps in the formation of starch (Bertoft, 2017)
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