A possible regulatory role for ethylene in the pollen-pistil interaction in a sporophytic self-incompatible system

Abstract

The sporophytic type of self-incompatibility exhibited by Ipomoea cairica Sweet (Convolvulaceae) was partially overcome in vitro by treating the pollen and/or stigma with 10−6 to 10−1 M methionine, a precursor of ethylene. The implications of these observations are discussed in relation to other experiments involving use of the ethylene antagonist AgNO3, individually and in combination with methionine and an optimum level of indole-3-acetic acid (10−2 M). The results suggest a role for ethylene (which could also be IAA-induced) in regulating pollen germination and further tube growth in sporophytic self-incompatible systems. A hypothesis on the action of hormones in pollen germination and tube growth in a sporophytic self-incompatible (SSI) system is presented.