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The After‐Effect of Water Stress on Chlorophyll Formation during Greening and the Levels of Abscisic Acid and Proline in Dark Grown Wheat Seedlings
Author(s) -
BENGTSON CURT,
KLOCKARE BIRGITTA,
KLOCKARE RUNE,
LARSSON STIG,
SUNDQVIST CHRISTER
Publication year - 1978
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1978.tb02565.x
Subject(s) - abscisic acid , proline , greening , chlorophyll , protochlorophyllide , chemistry , chlorophyll a , horticulture , chloroplast , botany , biology , biochemistry , amino acid , ecology , gene
Cut seedlings of wheat plants (Triticum aestivum L. cv. Starke II Weibull) between 6 and 7 days old were water stressed in darkness by exposing them to air of 35% relative humidity 2.5 to 20 h. This treatment resulted in a water potential of ‐11 bars in the leaves after 20 h. The leaves were then rewatered and irradiated. The chlorophyll formation that took place in fully turgid leaves during the greening was markedly decreased in the case of the water‐stress pretreatmet. and especially the lag phase was prolonged. The longer the stress pretreatment the more evident was the subsequent effect on chlorophyll formation. However, no linear relationship was found between the amount of stress and the chlorophyll content. Protochlorophyllide regeneration from endogenously formed δ‐aminolevulinic acid was markedly decreased even after the shortest water‐stress period. However, protochlorophyllide accumulation from exogenously supplied δ‐aminolevulinic acid was only slightly decreased following the water‐stress pretreatment. Further more, the ratio of protochlorophyllide 650 to protochlorophyllide 628 was slightly reduced by the same conditions. During the stress period both abscisic acid and proline were accumulated in the leaves. The content of abscisic acid increased up to six times the normal level during water stress lasting for 20 h. The increase of proline was about three‐fold for similar treatment. After rewatering the leaves the levels of both abscisic acid and proline rapidly declined and reached. 10 h later, the levels found in unstressed seedlings. The increase in abscisic acid during water stress associated with impaired chlorophyll metabolism suggested that the after‐effect of water stress might be linked to chlorophyll metabolism through abscisic acid or some of its metabolites. The changes in proline content open the possibility that this substance could function as a reserve substance for the formation of chlorophyll after the discon tinuation of the stress.