Alterations in the activities of the enzymes of proline metabolism in Ragi (Eleusine coracana) leaves during water stress |
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Authors: | Rajendra P. Kandpal C. S. Vaidyanathan M. Udaya Kumar K. S. Krishna Sastry N. Appaji Rao |
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Affiliation: | (1) Department of Biochemistry, Indian Institute of Science, 560 012 Bangalore;(2) Department of Crop Physiology, University of Agricultural Sciences, G.K.V.K. Campus, 560 065 Bangalore |
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Abstract: | Free proline content in Ragi (Eleusine coracana) leaves increased markedly (6 to 85 fold) as the degree of water stress, created by polyethylene gylcol treatment, was prolonged There was also a marginal increase in soluble proteins in the stressed leaves as compared to that in the controls. Water stress stimulated the activities of ornithine aminotransferase and pyrroline-5-carboxylate reductase, the enzymes of proline biosynthesis and markedly inhibited the enzymes involved in proline degradation viz., proline oxidase and pyrroline-5-carboxylate dehydrogenase. These results suggest that increase in free proline content of Ragi leaves could be due to enhanced activities of the enzymes synthesizing proline but more importantly due to severe inhibition of the enzymes degrading proline. These observations establish for the first time, the pathway of proline metabolism in plants by way of detection of the activities of all the enzymes involved and also highlight the role of these enzymes in proline accumulation during water stress. |
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Keywords: | Proline water stress Eleusine coracana ornithine aminotransferase pyrroline-5-carboxylate reductase proline oxidase pyrroline-5-carboxylate dehydrogenase |
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