Expression of chloroplastic genes during autumnal senescence in a deciduous tree Populus deltiodes.

Abstract

In Populus deltoides, a deciduous tree, the development on new leaves starts in the month of March, the leaves reach maturity by October and fall by December. Changes in the composition and function of the photosynthetic apparatus were analysed during autumnal senescence. With the progress of senescence, there was an initial increase followed by a decrease in the steady state levels of psbA, psbD/C and psaA/B gene transcripts. Decrease in the steady state level of D1 protein was faster than that of Cytochrome f. The decline in LHCP level was seen only during late senescence. Although the leaves continue to look green and healthy till late November, the electron transport driven by individual photosystems started declining by October end suggesting the onset of senescence.