Respiration metabolism in mitochondria of pea seedlings of different age under water deficit and rewatering

Respiration metabolism in mitochondria of pea seedlings of different age under water deficit and... The effects of an osmoticum (mannitol) on growth, water content, respiration, and proline content in epicotyls of etiolated two-day-old (S2) and three-day-old (S3) pea (Pisum sativum L., cv. Flora-2) seedlings were studied. Water deficit was produced by placing plant roots in 0.6 M mannitol for 2–4 days. Control S3 epicotyls contained more water than S2 epicotyls; they were also characterized by more intense mitochondrial activity (in state 3, V 3) and by the higher value of the respiratory control (RC) due to a fourfold decrease of proportion of weakly phosphorylating cyanide-resistant respiration (CRR). After 2-day-long treatment with the osmoticum, S2 epicotyls lost more water than S3; water deficit in them attained 40% (28% in S3). In S3 treatment, epicotyls continued to grow at the almost unchanged rate, and the content of proline in them changed insignificantly, whereas in S2 seedlings epicotyl growth stopped, and proline accumulated in them. In the presence of the osmoticum, V 3 and RC reduced, but in S3 treatment they retained higher than in treatment S2. In mitochondria of S3 subjected to dehydration, the proportion of the cytochromic pathway of oxidation (V cyt) remained high, but the absolute values of the respiration rate reduced, whereas in S2 both these indices reduced and the proportion of CRR increased. After rewatering, indices of mitochondrial activity (the rate of substrate oxidation, RC value) were restored, but in S3 they were higher. The ratio of V cyt to CRR in S3 shifted toward CRR, whereas in S2, in contrast, it was shifted toward V cyt. When temperature during seedling growth and experiment performing was declined from 22°C (in control) to 18°C, growth of S3 epicotyls was retarded to the rate characteristic of S2 at 22°C. Under the effect of osmoticum, they, like S2, acquired a capacity to accumulate proline. Nevertheless, mitochondrial activity in such S3 turned out to be higher than in S2 grown at 22°C. The results obtained than, as distinct from traditional notes, 3-day-old pea seedlings manifested the higher tolerance to water deficit than 2-day-old seedlings. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Russian Journal of Plant Physiology Springer Journals

Respiration metabolism in mitochondria of pea seedlings of different age under water deficit and rewatering

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Publisher
SP MAIK Nauka/Interperiodica
Copyright
Copyright © 2012 by Pleiades Publishing, Ltd.
Subject
Life Sciences; Plant Sciences; Plant Physiology
ISSN
1021-4437
eISSN
1608-3407
D.O.I.
10.1134/S1021443712020021
Publisher site
See Article on Publisher Site

Abstract

The effects of an osmoticum (mannitol) on growth, water content, respiration, and proline content in epicotyls of etiolated two-day-old (S2) and three-day-old (S3) pea (Pisum sativum L., cv. Flora-2) seedlings were studied. Water deficit was produced by placing plant roots in 0.6 M mannitol for 2–4 days. Control S3 epicotyls contained more water than S2 epicotyls; they were also characterized by more intense mitochondrial activity (in state 3, V 3) and by the higher value of the respiratory control (RC) due to a fourfold decrease of proportion of weakly phosphorylating cyanide-resistant respiration (CRR). After 2-day-long treatment with the osmoticum, S2 epicotyls lost more water than S3; water deficit in them attained 40% (28% in S3). In S3 treatment, epicotyls continued to grow at the almost unchanged rate, and the content of proline in them changed insignificantly, whereas in S2 seedlings epicotyl growth stopped, and proline accumulated in them. In the presence of the osmoticum, V 3 and RC reduced, but in S3 treatment they retained higher than in treatment S2. In mitochondria of S3 subjected to dehydration, the proportion of the cytochromic pathway of oxidation (V cyt) remained high, but the absolute values of the respiration rate reduced, whereas in S2 both these indices reduced and the proportion of CRR increased. After rewatering, indices of mitochondrial activity (the rate of substrate oxidation, RC value) were restored, but in S3 they were higher. The ratio of V cyt to CRR in S3 shifted toward CRR, whereas in S2, in contrast, it was shifted toward V cyt. When temperature during seedling growth and experiment performing was declined from 22°C (in control) to 18°C, growth of S3 epicotyls was retarded to the rate characteristic of S2 at 22°C. Under the effect of osmoticum, they, like S2, acquired a capacity to accumulate proline. Nevertheless, mitochondrial activity in such S3 turned out to be higher than in S2 grown at 22°C. The results obtained than, as distinct from traditional notes, 3-day-old pea seedlings manifested the higher tolerance to water deficit than 2-day-old seedlings.

Journal

Russian Journal of Plant PhysiologySpringer Journals

Published: Feb 26, 2012

References

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