GAMETOPHYTE INCOMPATIBILITY IN PETUNIA - DYNAMICS OF CARBOHYDRATES INTHE PROCESS OF POLLEN-TUBE GROWTH

We determined the content of soluble carbohydrates (sucrose, fructose, glucose) in pistils of Petunia hybrida L. after compatible and incomp atible pollination. Certain differences of carbohydrate dynamics in fu nctionally different parts of the pistil (style and ovary) were dictat ed by growth of compatible pollen tubes ensuring delivery of male game tes to the embryo sac after 22 h or the presence of incompatible polle n tubes, whose growth was shut down in style tissues 8-10 h after poll ination due to genetically determined gametophyte self-incompatibility . The incompatibility response here was accompanied by an elevated lev el of sucrose and fructose in style tissues. Following rejection of in compatible pollen tubes, accumulation of the three investigated carboh ydrates was also observed in ovules. It is concluded that sucrose is t he source of carbohydrate nutrition for pollen tubes of petunia, while glucose is the main carbohydrate component of forming walls of the po llen tube. The results are discussed in connection with available data on the mechanism of gametophyte incompatibility, including informatio n about expression of the S-gene and signal molecules.