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Diel leaf growth cycles in Clusia spp. are related to changes between C 3 photosynthesis and crassulacean acid metabolism during development and during water stress
Author(s) -
WALTER ACHIM,
CHRIST MAJA M.,
RASCHER UWE,
SCHURR ULRICH,
OSMOND BARRY
Publication year - 2008
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2008.01777.x
Subject(s) - diel vertical migration , crassulacean acid metabolism , photosynthesis , biology , botany , relative growth rate , facultative , ecophysiology , nocturnal , light intensity , horticulture , growth rate , ecology , geometry , mathematics , physics , optics
This study reports evidence that the timing of leaf growth responds to developmental and environmental constraints in Clusia spp. We monitored diel patterns of leaf growth in the facultative C 3 ‐crassulacean acid metabolism (CAM) species Clusia minor and in the supposedly obligate CAM species Clusia alata using imaging methods and followed diel patterns of CO 2 exchange and acidification. Developing leaves of well‐watered C. minor showed a C 3 ‐like diel pattern of gas exchange and growth, with maximum relative growth rate (RGR) in the early night period. Growth slowed when water was withheld, accompanied by nocturnal CO 2 exchange and the diel acid change characteristic of CAM. Maximum leaf RGR shifted from early night to early in the day when water was withheld. In well‐watered C. alata , similar changes in the diel pattern of leaf growth occurred with the development of CAM during leaf ontogeny. We hypothesize that the shift in leaf growth cycle that accompanies the switch from C 3 photosynthesis to CAM is mainly caused by the primary demand of CAM for substrates for nocturnal CO 2 fixation and acid synthesis, thus reducing the availability of carbohydrates for leaf growth at night. Although the shift to leaf growth early in the light is presumably associated with the availability of carbohydrates, source–sink relationships and sustained diurnal acid levels in young leaves of Clusia spp. need further evaluation in relation to growth processes.