PhD Proposal Exam
Tuesday, June 27th, 2017 at 10:10 am – Earth Sciences Centre, Rm. 3087
Sonhita Chakraborty (Yoshioka lab)
“Investigation of the interplay between CYCLIC NUCLEOTIDE GATED ION CHANNEL 2 (CNGC2), Ca2+ and auxin signaling”
Cyclic nucleotide-gated channels (CNGCs) are non-selective cation channels that were first discovered in animals, where they were reported to be involved in visual and olfactory systems. While the biological role and channel properties of animal CNGCs have been well studied, not much is known about these channels in plants. The Arabidopsis thaliana CNGCs consists of twenty members, that have been implicated in development, ion homeostasis, thermotolerance, and pathogen defense. The “defense, no death” dnd1 and dnd2/hlm1, mutants of CNGC2 and CNGC4 respectively, exhibit autoimmune phenotypes such as dwarf morphology, constitutive expression of PR genes and elevated salicylic acid (SA) levels. To elucidate CNGC2-mediated signaling, repressor of defense no death 1 (rdd1), the first suppressor of dnd1 was identified. rdd1 is a loss-of-function mutation in YUC6, an auxin biosynthesis gene. Recent data shows that dnd1 has alterations in auxin signaling and auxin-induced Ca2+ flux. I hypothesize that CNGC2 is involved in development and auxin signaling in addition to its role in plant immunity. The aim of this project is to understand CNGC2-mediated signaling by elucidating the mechanism by which rdd1-1 supresses dnd1. YUC6 is involved in auxin biosynthesis and ROS homeostasis. Hence, I will explore if the suppression of dnd1 is through either of these functions. CNGC2 might also be important for auxin transport. Results from this project will provide new insights into the role of auxin in CNGC2 and Ca2+ signaling in the context of plant immunity.