Variation in protein fractions and their correlation studies in rice

In contrast to earlier studies on the separation of seed protein fractions in one line only, a number of rice lines have been analyzed for variation in different protein characteristics like seed protein content, proportion of four protein fractions viz. albumins, globulins, glutelins and prolamins and amino acid content of different fractions followed by correlations amongst these. As is known for rice proteins, the glutelins represented the dominating fraction with their proportion varying from 54.5 to 69.8% in different lines. This was followed by prolamins (15.5 – 21.1%), globulins (8.8 – 15.9%) and albumins (5.9 – 10.8%). Estimation of three essential amino acids viz. tryptophan, methionine and lysine, showed that glutelins were the poorest for all these amino acids, albumins had the highest content of lysine (2.0–8.3 g/100g protein) and methionine (3.8–9.5 g/100g protein) while globulins had the highest tryptophan (1.1–3.7 g/100g protein). A highly significant positive correlation was exhibited between protein content and proportion of globulin and prolamins. Similarly, lysine content of prolamins and proportion of glutelins was found to be negatively correlated. In contrast, a significant positive correlation was observed between lysine content of globulins and glutelins.