Characterization of Functional Genes GS3 and GW2 and their Effect on the Grain Size of Various Landraces of Rice
Abstract Grain size is an essential factor in grain quality and yield. In the existing agricultural lands in Pakistan and even all over the world, genetics in rice works better for yield potential and quality improvement. GS3 and GW2 with functional mutation responsible for grain size in rice. In the current study, 17 different Pakistani landraces of various genetic and geographic backgrounds were evaluated for grain phenotypic traits (thousand-grain weight, length, width, and thickness) and characterized genotypes for GS3 gene (grain length) and GW2 (grain width). The two accessions JP5 and Bas370, were used as control. Phenotypic data revealed the range for grain weight from 16.86g (Lateefy) to 26.91g (PS2), grain length ranged from 7.27 mm (JP-5) to 12.18 mm (PS2), grain width ranged from 2.01 mm (Lateefy) to 3.51 mm (JP5), and grain thickness ranged from 1.79 mm to 2.19. Pearson correlation revealed a negative and significant correlation between grain width and length. There was no significant correlation between grain length and 1000-grain weight and grain width. LSD test displayed that the means of three variables grain length, grain width, and 1000-grain weight were statistically different from one another except grain width and grain breadth. GS3 is a negative regulator of grain length. Fifteen accessions GA-5015, PS-2, Swat-1, Swat-2, DR-2, Dilrosh, Malhar-346, Kashmir Basmati, Rachna Basmati, KS-282, Basmati-370, KSK-133, KSK-434, MG-Basmati, and Lateefy, carried the domesticated allele of GS3 while JP5 and Fakhr-e-Malakand carried the dominant allele. Similarly, the GW2 is a negative regulator of grain width. Fifteen accessions, i.e., Bas-370, GA-5015, PS-2, Swat-1, Swat-2, DR-2, Dilrosh, Malhar-346, Kashmir Basmati, Rachna Basmati, KS-282, KSK-133, KSK-434, MG-Basmati, and Lateefy carried the dominant allele while JP-5 and Fakhr-e-Malakand carried the mutant allele. The current phenotypic evaluation of the Germplasm revealed a diverse range of grain size of Pakistani landraces and also suggests that the selection of grain length in Pakistani landraces was independent of 1000-grain weight. The accessions with genotypic characterization will aid in marker-assisted breeding programs to break the stagnant yield prevail for the last few decades in Pakistan.