Nucleic acid metabolism of seeds of pigeonpea (Cajanus cajan (L.) Millsp.) cultivars during accelerated ageing
1997
Kalpana, R. | Madhava Rao, K.V. (Andhra University, Andhra Pradesh (India). Department of Botany)
Accelerated ageing of pigeonpea seeds led to a progressive decline in viability. Though a decline in DNA and total RNA content was encountered with ageing, seed deterioration in pigeonpea cultivars may not depend on the DNA and RNA content but may be related to the structure and function of these molecules. 3H-thiamidine incorporation studies revealed that two-day "aged" seeds showed maximum incorporation and beyond two days of ageing treatment there was a continuous decline. 3H-uridine incorporation studies revealed greater incorporation in the accelerated aged seeds in the initial hours of imbibition, indicating the probable operation of a repair mechanism. With increasing imbibition time, high quality seed surpasses deteriorated seeds in utilisation of the supplied substrate. Even after eight days of accelerated ageing seeds retained the ability to synthesise DNA and RNA, though to a lesser extent than untreated seed lots. Hence there appears to be no complete loss of nucleic acid synthesis under accelerated ageing conditions. Alterations in the normal nucleic acid synthesis were a possibility, probably leading to greater synthesis of hydrolytic enzymes and seed deterioration. The enzyme RNase showed a continuous rise in activity with increasing duration of ageing treatment and probably plays an important role in the mechanism of ageing of seeds of pigeonpea cultivars
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