期刊
JOURNAL OF PLANT PHYSIOLOGY
卷 161, 期 11, 页码 1211-1224出版社
ELSEVIER GMBH
DOI: 10.1016/j.jplph.2004.01.014
关键词
chlorophyll fluorescence; drought; heat; NADP; proline; soybean
The biochemical basis of heat/drought tolerance was investigated by comparing the response of antisense and sense transgenic soybean plants (containing the L-Delta(1)-pyrroline-5-carboxylate reductase gene) with non-transgenic wild-type plants. The plants were subjected to a simultaneous drought and heat stress of 2 days, whereafter they were rewatered at 25degreesC. During this time the sense plants only showed mild symptoms of stress compared to the antisense plants which were severely stressed. Upon stress, nicotinamide adenine dinucleotide phosphate (NADP(+)) levels decreased in antisense white it increased in sense plants. Recovery with respect to NADP(+) levels was best in sense plants. Sense plants had the highest ability to accumulate proline during stress and to metabolise proline after rewatering. Analyses of the fast phase chlorophyll-a fluorescence transients showed dissociation of the oxygen-evolving complex (OEC) upon stress in all. plants tested. In the sense plants, which best resisted the stress, OEC dissociation was bypassed by proline feeding electrons into photosystem 2 (PSII), maintaining an acceptable nicotinamide adenine dinucleotide hydrogen phosphate (NADPH) Level, preventing further damage. Upon recovery, NADPH is consumed during oxidation of accumulated proline providing high levels of NADP(+) to act as electron acceptor to PSII, which indirectly may ameliorate the inhibition and/or the effect of uncoupling of the OEC. (C) 2004 Elsevier GmbH. All rights reserved.
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