ENVIRONMENTAL AND HORMONAL REGULATION OF ROOT GROWTH IN ARABIDOPSIS

Abstract

Phytohormones are key regulators for plant development in every aspect, of which auxin and ethylene are the most important ones. In my study, we systematically investigated how auxin and ethylene are coordinated in regulation of root growth in Arabidopsis. CTR1 is the repressor for ethylene pathway, and ctr1-8 mutant shows a consecutive enhanced ethylene signaling. Interestingly, we found that ctr1-8 mutant also exhibits an elevated auxin signaling. Using RNA-Seq and bioinformatics method, we have identified a novel gene HB52, acting downstream of CTR1 and EIN3, regulates cellular auxin level through promoting the expression of auxin biosynthesis gene YUCCA7. Cellular auxin level determines the size of cell size at elongation zone, thus, root growth rate. To our knowledge, our study is the first time that connects ethylene signaling to auxin biosynthesis in regulation of root growth.