THE PLANT CELL, Vol 6, Issue 1 11-23, Copyright © 1994 by American Society of Plant Biologists
Pollination- or Wound-Induced Kaempferol Accumulation in Petunia Stigmas Enhances Seed Production
T. Vogt, P. Pollak, N. Tarlyn and L. P. Taylor
Department of Horticulture and Program in Plant Physiology, Washington State University, Pullman, Washington 99164-6414
Flavonols are essential for pollen germination and tube growth in petunia
and can be supplied by either the pollen or stigma at pollination. HPLC
analysis and a sensitive bioassay demonstrated that both pollination and
wounding induce flavonol accumulation, especially kaempferol, in the outer
cell layers and exudate of the stigma. Pollination and wounding induced
nearly identical flavonol kinetics and patterns of accumulation in the same
target tissue, suggesting that they share elements of a common signal
transduction pathway. The wound response was systemic, because kaempferol
accumulated in the stigma when distal tissues, such as the corolla,
stamens, or sepals, were wounded. We have exploited the germination
requirement for flavonols and the high level of kaempferol that accumulates
after wounding to enhance plant fecundity. Seed set was significantly
increased by mechanically wounding the corolla and stamens prior to the
application of pollen to the stigma. A reproductive role for a plant
secondary metabolite and the specific function of stigmatic kaempferol are
discussed from an evolutionary perspective.
