Gravistimulation changes the accumulation pattern of the CsPIN1 auxin efflux facilitator in the endodermis of the transition zone in cucumber seedlings.

Cucumber (Cucumis sativus) seedlings grown in a horizontal position develop a specialized protuberance (or peg) on the lower side of the transition zone between the hypocotyl and the root. This occurs by suppressing peg formation on the upper side via a decrease in auxin resulting from a gravitational response. However, the gravity-stimulated mechanism of inducing asymmetric auxin distribution in the transition zone is poorly understood.

Isolation of auxin efflux carrier cDNA from cucumber.

Cucumber seedlings display not only gravitropism but also peg formation in response to gravity. Gravimorphogenesis is mediated by auxin distribution. As first step to reveal the mechanism that regulates auxin distribution by auxin efflux, we isolated five partial cDNAs of auxin efflux carriers by RT-PCR method.