Translocation and partitioning patterns of C-14 photoassimilate from light- and shade-adapted shoots in greenhouse-grown 'Chardonnay' grapevines (Vitis vinifera L.)

摘要

Potted Chardonnay' grapevines (Vitis vinifera L.) with either two or three shoots were grown in a greenhouse for one month and then transferred to a phytotron room, where either one or two shoots were shaded. Twenty-four days after transfer, leaves at the fifth node of either the light-adapted or shade-adapted shoot were exposed to 12-hour pulse Of (CO2)-C-14. Both light environment and number of shade shoots on the vine had a significant effect on photosynthate partitioning within the plant following a 22-hour chase. Leaves fed with (CO2)-C-14 on a light-adapted shoot translocated 26.1% and 12.7% more radioactivity to the roots and trunk, respectively, than leaves from shade-adapted shoots. Photosynthates were exported from light-adapted leaves to shade-adapted shoots (1.3% of total C-14 in plant). The number of shaded shoots and the light environment of the fed leaf had a large effect on partitioning of photosynthates among ethanol-insoluble, water-soluble, and chloroform-soluble fractions within the leaf. Recovered C-14 in the water-soluble fraction of the fed leaf appeared to be affected more by number of shoots than by light environment of the fed leaf. The data suggest that there is a sink effect on initial carbon partitioning patterns in grapevine leaves. Sink strength may have a greater role than light environment. A large proportion of interior leaves versus exterior leaves may be costly with respect to the carbohydrate budget of a vine.