Figure 5.
Acceleration and Alleviation of the Dark Treatment Phenotype and ATP/ADP ratios in wild-type and pxa1 plants.
(A) Leaf phenotype of 19-d-old adg1-1 plants expressing a PXA1 amiRNA construct grown in continuous light before dark treatment.
(B) Phenotype alleviation through feeding of exogenous sucrose. Three-week-old pxa1-2 and Col-0 plants grown on sterile half-strength MS medium supplemented either with (2%) or without sucrose were exposed to 39 h of darkness and subsequently returned to light for 24 h. pxa1-2 plants grown without exogenous sucrose experienced severe leaf damage and bleaching from this treatment compared with plants grown on sucrose-containing media. This finding was consistent with IMAGING-PAM (pulse amplitude modulation) fluorescence pictures showing either ΦPSII or Fv/Fm in false colors. PAM data were collected before plants were returned to light. Both values were markedly higher in mutants when sucrose was added to the media.
(C) ATP/ADP ratio in leaves of the wild type and pxa1 after different periods of darkness. Average ± se (n = 3 to 4).
(D) Total free fatty acid concentration in leaves of plants grown on half-strength MS medium supplemented with or without sucrose and harvested after 0 and 39 h of darkness. Average ± se (n = 3 to 4).