OsEIL1 affects auxin biosynthesis in ethylene-inhibited rice root elongation

The role of crosstalk between auxin and ethylene in primary root development has been studied in the dicot model plant Arabidopsis thaliana, but is less well understood in monocots. Through a genetic screen for roots that elongate in the presence of ethylene , Qin, Zhang et al. identified a mutant rice ethylene insensitive (rein7-1). REIN7 corresponds to YUC8 (YUCCA8), an enzyme involved in the conversion of IPA (indole-3-pyruvic acid) to IAA (indole-3-acetic acid). Mutation of REIN7/YUC8 reduces auxin biosynthesis, and over expression of it induces ethylene sensitivity in root. Further genetic analysis showed that REIN7/YUC8 acts downstream of OsEIL1 and is transcriptionally activated by OsEIL1. The authors propose a model for how ethylene promotes auxin synthesis and inhibits rice root elongation. (Summary by Arif Ashraf) PLOS Genetics 10.1371/journal.pgen.1006955