| Results and Discussion a) Soluble proteins Crude seed extract revealed highest estimate of soluble protein. As the germination progressed to one week stage, soluble protein content decreased steadily in all isogenic lines as well as in control cultivars (Table 1). Three fold decrease was noted at one week stage over the zero hour stage. Decrease in soluble protein content can be well correlated with mobilization of reserves from the storage tissues and transfer of solubilized derivatives to the growing embryo axis during termination (Ledoux et al 1962). Breevers (1968) observed an ordered series of events leading to degradation of storage proteins in legumes. Two distinct reductions at 24 hr and 96 hr stages were observed. First reduction is attributable to higher activity of proteases in the germinating seeds (Koller et al 1962). Whereas reduction at later stage could be due to higher activity of ribonucleases (Leduox, et al 1962, Vold and Sypherd 1968) which degrade RNA molecules and thus affect protein synthesis. b) Ribonucleases The lowest specific activity was recorded for RNase I and RNase II + Nu I in the crude seed extract. Ninety-six hr stage marked four fold increase in specific activity when compared to zero hour stage (Table 2). At one week stage activity was less than that of 96 hr stage. Rise in ribonucleases activities have been observed in germinating seeds of barley (Leduox et al 1962), wheat (Vold and Sypherd 1968) and pea (Barker et al 1974). Grellet et al (1968) observed parallel increase in RNase activity with RNA synthesis and accumulation during germination. Low activity at one week stage may be due to the dilution of RNases. There were not much differences in the specific activity amongst genotypes with or without Lr genes. RNase II + Nu I showed more activity compared to RNase I at comparable stages of germination. A negative relationship was observed between soluble protein and specific activity of RNases. Such a relationship emphasizes the control of ribonucleases on protein degradation and protein synthesis during germination. Acknowledgement Financial assistance received from the university is gratefully acknowledged. |
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