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Loss of chlorophylls, cessation of photosynthetic CO 2 assimilation and respiration in the poikilochlorophyllous plant Xerophyta scabrida during desiccation
Author(s) -
Tuba Z.,
Lichtenthaler H. K.,
Csintalan Zs.,
Nagy Z.,
Szente K.
Publication year - 1996
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.1399-3054.1996.tb00448.x
Subject(s) - desiccation , photosynthesis , respiration , biology , botany , chlorophyll fluorescence , chlorophyll , assimilation (phonology) , thylakoid , desiccation tolerance , chlorophyll a , chloroplast , biochemistry , linguistics , philosophy , gene
During a slow desiccation in photosynthetically fully active leaves of the poikilochlorophyllous desiccation‐tolerant (PDT) monocotyledon Xerophyta scabrida (Pax) Th. Dur. et Schinz (Velloziaceae), thylakoid activity, CO 2 assimilation and respiration decline and chlorophylls and carotenoids are successively broken down. The initially slow rate of leaf water loss is related to the large reduction in leaf area which is reflected in the decrease of specific leaf area. Chlorophylls are broken down faster than carotenoids. The ratio of the variable chlorophyll fluorescence, an indicator of photosynthetic activity (Rfd690‐values), shows that the functionality of thylakoids and chlorophylls is successively lost during desiccation. The decline in net CO 2 assimilation in desiccating leaves is largely caused by stomatal closure. The complete cessation of CO 2 assimilation, however, is due to the breakdown of chlorophylls and thylakoids. Respiration continued during desiccation and remained active far below ‐3.2 MPa leaf water potential. The differences during desiccation of the photosynthetic apparatus between poikilochlorophyllous and homoiochlorophyllous desiccation‐tolerant plants are discussed.