Abstract
We have shown that an agravitropic pea mutant, ageotropum, seedlings showed automorphosis-like growth and auxin polar transport of the first internode of etiolated epicotyls was substantially suppressed to lower than 50 % of that in etiolated Alaska pea epicotyls. We have also isolated novel cDNAs containing the complete open reading frames of a putative auxin influx facilitator, PsAUX1, and putative auxin efflux facilitators, PsPIN1, PsPIN2 and PsPIN3, from etiolated epicotyls of ageotropum. No deletion and insertion of nucleotides in these genes isolated from ageotropum pea was found compared to those in Alaska pea. Expression of PsAUX1, PsPIN1, PsPIN2 and PsPIN3 genes in the first internode of etiolated ageotropum and Alaska pea epicotyls were almost same during early growth stage of the seedlings. These results strongly suggest that automorphosis-like growth and reduced auxin polar transport in etiolated ageotropum pea epicotyls do not depend on structure and function, and gene expression of PsAUX1 and PsPINs but on different mode of actions of other molecules regulating auxin polar transport and/or dynamics of PsAUX1 and PsPINs between ageotropum and Alaska pea seedlings.
