Genetics, Development and Cell Biology Ph.D. Candidate: Zhouli Xie

Major: Plant Biology

Major professor: Yanhai Yin

Title: The AP2/ERF Transcription Factor TINY Modulates Brassinosteroid-Regulated Plant Growth and Drought Response in Arabidopsis.

Abstract: In order to survive environmental stresses while optimizing their growth, plants must precisely modulate their growth and stress response programs. Plant steroid hormone Brassinosteroids (BRs) promote plant growth and inhibit drought responses through central transcription factors BES1 and BZR1 in the BR signaling pathway. Although the roles AP2/ERF transcription factors in stress responses are well documented, their functions in the trade-off between stress and growth have not been established. Here, we found that drought inducible AP2/ERF family transcription factor TINY antagonizes with BR pathway to inhibit BR-regulated growth but promotes BR-repressed drought response. TINY interferes BR-induced plant growth by reducing BR signaling. Accordingly, TINY overexpression plants have a stunted growth phenotype, display higher sensitivity to BR biosynthesis inhibitors and negatively regulate BR-responsive genes. In contrast, tiny tiny2 tiny4 triple mutant leads to increased plant growth and resistance to inhibition of BR biosynthesis as well as induced BR responsive genes. TINY promotes ABA-mediated stomatal closure and confers drought tolerance by activating drought responsive genes. The globe gene expression studies reveal that TINY opposes BR-regulated gene expression involved in plant growth and stress response. TINY interacts and antagonizes with BES1 on these genes. In addition, BIN2, phosphorylates and stabilizes TINY, providing a mechanism by which BRs function to inhibit TINY function to prevent unnecessary activation of drought responses. Our results thus reveal that TINY not only functions to promote drought response and inhibit plant growth by modulating BR pathway, but also acts as a target for BR signaling during plant growth.

Biography:
Zhouli Xie is a six-year Ph.D. student in Dr. Yanhai Yin’s lab and focuses on studying the cross-talk between stress and BR pathway. Zhouli received her master of science in plant physiology from China Agricultural University in 2013.