Characterization Studies on Seed Storage Proteins in Rice Autotetraploids

Seed storage proteins of four diploid rice lines vis-a-vis their respective tetraploids supplied by National Institute of Agrobiological Sciences.., Japan, were studied. The autotetraploids had a higher protein content as compared to their parental lines; maximum relative increase of 63% being in case of tetraploid of the parental line ʹKumaʹ. The alkali soluble proteins i.e. glutelins were the dominating fraction in the four rice lines and their autotetraploids. Whereas tetraploids of the lines ʹPusurʹ, ʹKumaʹ and ʹTougouʹ had higher glutelins and prolamins as compared to their parental lines, ʹNourinʹ tetraploid had relatively lesser proportion of the glutelins and prolamins. The proportion of albumins and globulins in the seeds of tetraploids of ʹPusurʹ, ʹKumaʹ and ʹTougouʹ decreased and that in the tetraploid of ʹNourinʹ registered an increase. With major polypeptides resolving in the range of mol. wt. 110 kDa to 13 kDa, SDS-PAGE of the total seed protein extracts of diploids and their tetraploids under non-reducing and reducing conditions did not show any qualitative difference in their polypeptides patterns. Most of the polypeptides of tetraploids of ʹNourinʹ and ʹPusurʹ looked darker as compared to their respective diploid parents. Densitometric scanning of gels exhibited more than 10% increase in relative concentration of polypeptides of mol.wt. 78 kDa, 65 kDa, 60 kDa, 40.5 kDa, 38 kDa, 36 kDa, 29 kDa, 25 kDa, 21 kDa and 13 kDa in ʹNourin 4xʹ, 78 kDa, 36 kDa, 21 kDa and 13 kDa in ʹKuma 4xʹ, 78 kDa, 65 kDa, 40.5 kDa, 38 kDa, 36 kDa, 25 kDa and 21 kDa in ʹ Pusur 4xʹ and 38 kDa and 21 kDa in ʹTougou 4xʹ. Maximum densitometric increase was noticed for polypeptides of mol.wt. 25 kDa in ʹNourin 4xʹ, 21 kDa in ʹKuma 4xʹ, 36 kDa in ʹPusur 4xʹ and 38 kDa in ʹTougou 4xʹ as compared to their respective diploid parents.