RAPID PHOTOSYNTHETIC ADAPTATION TO HEAT-STRESS TRIGGERED IN POTATO LEAVES BY MODERATELY ELEVATED-TEMPERATURES

Authors
Citation
M. Havaux, RAPID PHOTOSYNTHETIC ADAPTATION TO HEAT-STRESS TRIGGERED IN POTATO LEAVES BY MODERATELY ELEVATED-TEMPERATURES, Plant, cell and environment, 16(4), 1993, pp. 461-467
Citations number
31
Categorie Soggetti
Plant Sciences
Journal title
ISSN journal
01407791
Volume
16
Issue
4
Year of publication
1993
Pages
461 - 467
Database
ISI
SICI code
0140-7791(1993)16:4<461:RPATHT>2.0.ZU;2-O
Abstract
Photosystem II (PSII) is considered to be one of the most thermolabile aspects of photosynthesis. In vivo measurements of chlorophyll fluore scence and photosynthetic oxygen evolution in 25-degrees-C-grown potat o leaves (cv. Haig) indicated that the threshold temperature T(C) abov e which PSII denatures was indeed rather low - about 38-degrees-C - wi th temperatures higher than T(C) causing a rapid and irreversible loss of PSII activity. The present study demonstrates the existence of ada ptive processes which rapidly adjust the in vivo thermal stability of PSII in response to temperature increase. Transfer of potato leaves fr om 25-degrees-C to temperatures slightly lower than T(C) (between 30 a nd 35-degrees-C) was observed to cause an upward shift of the T(C) val ue without any appreciable loss of PSII activity. This increase in PSI I thermotolerance was substantial (around +5-degrees-C in the Haig cul tivar), rapid (with a half-time of approximately 20 min) and slowly re versible at 25-degrees-C (>24h). As a consequence, high temperatures ( e.g. 40-degrees-C) which caused a complete and irreversible inhibition of the PSII function had very little effect in 35-degrees-C-treated l eaves, thus suggesting that the above-described PSII changes could be of prime importance for the plant's behaviour in the field. Accordingl y, the rise in T(C) at 35-degrees-C was much larger (+8-degrees-C) in Sahel, a stress-resistant potato variety, than in the heat-sensitive H aig cultivar.