Identification and characterization of signal components in early ABA signaling in Arabidopsis

<p>The phytohormone abscisic acid (ABA) regulates growth, development, and response to abiotic stress in plants. The core ABA signaling has three key components: ABA receptors PYRABACTIN RESISTANCE 1 and PYR1-Like protein (PYR1/PYLs), type 2C protein phosphatases (PP2Cs) and SNF1- related protein Kinase 2s (SnRK2s). In the presence of ABA, PYR1/PYLs bind to and inhibit PP2Cs, leading to the release of SnRK2s from suppression, to activate downstream events such as ABA-responsive gene expression. To identify new components in the ABA signaling pathway, we performed a yeast two-hybrid screen for PYLs and SnRK2s interactors. We identified two proteins that interact with PYLs and SnRK2s: Ty pe One Protein Phosphatase 1 (TOPP1) and its regulatory protein At Inhibitor 2 (AtI-2). We show that TOPP1 and AtI-2 inhibit SnRK2.6 activity <em>in vitro</em> and that the inhibition is reversed by PYLs in the presence of ABA. Mutants <em>topp1-1topp4-1 </em>and <em>ati-2</em>are hypersensitive to ABA during seed germination. ABA-responsive genes are highly up regulated in <em>topp1-1topp4-1 </em>and <em>ati-2</em> mutants. Taken together, our results suggest that the TOPP1 and AtI-2 form a complex that negatively modulates ABA signaling by interacting with PYLs and SnRK2s</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Horticulture and Landscape Architecture

Year

2014

Author dc:creator

• Hou, Yueh-Ju

Contributors dc:contributor

• Jian-Kang Zhu
• Paul Michael Hasegawa
• David Rhodes
• Jin-Rong Xu

• Biology
• Botany

Repository record dc:identifier

https://docs.lib.purdue.edu/open_access_dissertations/288

OAI identifier oai:identifier

oai:docs.lib.purdue.edu:open_access_dissertations-1351