Self-sterility in Arabidopsis due to defective pollen tube guidance.

In flowering plants, a series of cell-cell interactions govern the delivery of sperm to the ovules through precise guidance of pollen tubes. Two Arabidopsis genes, POP2 and POP3, were found that mediate pollen tube guidance and are critical for self-fertility in diploid reproductive cells. The pop2 and pop3 mutations exhibited genetic redundancy: Self-sterility occurred only when male and female tissues were defective in both genes. This phenotype resembles that found in many self-incompatible species.