Molecular characterization of grain size locus in bread wheat Triticumaestivum L

Abstract

Bread wheat (TriticumaestivumL.) belonging to family poacea, one of the most important crops grown worldwide, accounts for 20% of the calories consumed by humans. It is a segmental hexaploid (2x=6n=42) with 21 pairs of chromosomes subdivided into three closely related (homoeologous) groups of chromosomes for three progenitor genomes A, B, and D; and each of these genomes contain seven pairs of chromosomes. Increase in wheat yield has always been an essential breeding target for the wheat breeders world. Grain size is an important target trait having larger influence on wheat yield and its quality. Till date, a number of genes associated with grain size have been identified in wheat including GS3, GS5, GW2, GW3, GW5, GW6, GW8, GIF1, andGhd7. newlineThe present study was carried out to characterise the TaGS5 grain size gene of wheat which is an orthologue of OsGS5 gene identified in rice. A core set of 96 wheat genotypes was characterised for the grain size traits by three methods namely-thousand grain weight (TGW), use of vernier caliper for the grain size measurement and digital analysis of grain size using SmartGrain software. Pearson correlation analysis of the data obtained using TGW and vernier caliper revealed positive correlation between grain length (GL), grain width (GW), and TGW. Further, length-width ratio (LWR) was positively correlated with GL and TGW, while it was negatively correlated with GW. The grain size analysis by SmartGrain also exhibited positive correlation between grain area, grain perimeter, GL and GW. The data obtained from vernier caliper and SmartGrain showed significant and positive correlation indicating the use of SmartGrain as a tool for high throughput seedanalysis. newlineThe molecular characterization of TaGS5 locus was carried using CAPS markers (reported earlier for 3A and 3D allele of TaGS5 locus in wheat genotypes of Chinese origin) and cloning of gene specific DNA sequences from TaGS5-3D locus. A desired polymorphism was obtained with CAPS analysis on TaGS5-3A locus