Pollination, wounding and jasmonate treatments induce the expression of a developmentally regulated pistil dioxygenase at a distance, in the ovary, in the wild potato Solanum chacoense Bitt.

Pollination and fertilization trigger unique developmental programs leading to embryogenesis, ovary maturation and seed set. Pistil tissues are actively involved in pollen tube growth and respond to the presence of the growing pollen tubes by modulating the expression of specific genes. Using subtractive hybridization to isolate genes involved in pollen-pistil interactions and fertilization, we have isolated a pollination- and fertilization-induced dioxygenase which is predominantly expressed in the pistil. In situ hybridization analyses revealed that the SPP2 dioxygenase (Solanum pollinated pistil) from the self-incompatible wild potato Solanum chacoense Bitt. is also developmentally regulated, with mRNA levels gradually regressing from the tip of the style towards the ovary during pistil development. At maturity, the upper limit of SPP2 transcript distribution coincided with the abscission zone of the style and SPP2 dioxygenase expression in ovaries coincided with the fertilization receptivity period of the flower. Pollination, as well as wounding of the style, induced an increase in SPP2 mRNA steady-state levels at a distance, in the ovary. Treatments with stress hormones including methyl jasmonate, jasmonic acid and salicylic acid mimicked the wound response and also induced SPP2 transcripts in the ovary. The SPP2 dioxygenase could be involved in the biosynthesis of deterrent alkaloids in reproductive tissues or in generating chemical signals involved in pollen tube guidance.