Premium
Mitochondria contribute to increased photosynthetic capacity of leaves of winter rye ( Secale cereale L.) following cold‐hardening
Author(s) -
HURRY V.,
TOBIÆSON M.,
KRÖMER S.,
GARDESTRÖM P.,
ÖQUIST G.
Publication year - 1995
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.1365-3040.1995.tb00545.x
Subject(s) - photosynthesis , secale , cold hardening , respiration , electron transport chain , chloroplast , oligomycin , botany , chlorophyll , biology , chlorophyll fluorescence , biophysics , chemistry , biochemistry , atpase , gene , enzyme
Cold‐hardening of winter rye ( Secale cereale L. cv. Musketeer) increased dark respiration from −2.2 to −3.9 μmol O 2 m −2 s −1 and doubled light‐and CO 2 ‐saturated photosynthesis at 20°C from 18.1 to 37.0μmol O 2 m −2 s −1 We added oligomycin at a concentration that specifically inhibits oxidative phosphorylation to see whether the observed increase in dark respiration reflected an increase in respiration in the light, and whether this contributed to the enhanced photosynthesis of cold‐hardened leaves. Oligomycin inhibited light‐ and CO 2 ‐saturated rates of photosynthesis in non‐hardened and cold‐hardened leaves by 14 and 25%, respectively, and decreased photochemical quenching of chlorophyll a fluorescence to a greater degree in cold‐hardened than in non‐hardened leaves. These data indicate an increase both in the rate of respiration in the light, and in the importance of respiration to photosynthesis following cold‐hardening. Analysis of metabolite pools indicated that oligomycin inhibited photosynthesis by limiting regeneration of ribulose‐1,5‐bisphosphate. This limitation was particularly severe in cold‐hardened leaves, and the resulting low 3‐phospho‐glycerate pools led to a feed‐forward inhibition of sucrose‐phosphate synthase activity. Thus, it does not appear that oxidative phosphorylation supports the increase in photo‐synthetic O 2 evolution following cold‐hardening by increasing the availability of cytosolic ATP. The data instead support the hypothesis that the mitochondria function in the light by using the reducing equivalents generated by non‐cyclic photosynthetic electron transport.