Bharath Pulimamidi
University of Hyderabad
Pulimamidi Bharath is a Ph.D. student at School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India. He completed B.Sc. (Biotechnology) from Rayalaseema University, Andhra Pradesh and M.Sc. in Genetics from Osmania University, Hyderabad, Telangana. He was a recipient of the University Rank Holders Fellowship from the University Grants Commission, India during M.Sc. Bharath joined the Ph.D. program in 2018 with Prof. Agepati Raghavendra. He started working on “Stomatal closure by abscisic acid or methylamine depends on V-ATPase mediated guard cell cytosolic pH changes followed by ROS production” for his doctoral degree. He focused on cytosolic pH changes in relation to reactive oxygen species and nitric oxide during stomatal closure in Arabidopsis thaliana. Bharath presented his research work at several international and national conferences, including 11th International Meeting on “Photosynthesis and Hydrogen Energy Research for Sustainability” held at Bahcesehir University Future Campus, Istanbul, Turkey. He was selected for the SAKURA Exchange Program in Science at Okayama University, Japan, and visited Japan in March 2024.
Title of presentation
Stomatal closure by abscisic acid or methylamine depends on V-ATPase mediated guard cell cytosolic pH changes followed by ROS production
Authors
Pulimamidi Bharath, Shashibhushan Gahir, Deepak Saini, Gudipalli Padmaja, Agepati S. Raghavendra
Department of Plant Sciences, University of Hyderabad, School of Life Sciences, Hyderabad 500046, India
Abstract
Stomatal closure by abscisic acid (ABA) is a common plant response during abiotic and biotic stress. Our experiments extensively studied the signaling components involved in stomatal closure by ABA. The researchers observed alkalinization of guard cells as an upstream event of ROS and Ca2+. There were also claims that H2O2 or Ca2+ induced guard cell alkalinization. We re-examined the modulation of guard cell cytosolic pH and its consequences on stomatal closure in Arabidopsis thaliana. Besides ABA, methylamine (MA, alkalinizing agent) caused cytosolic alkalinization leading to stomatal closure. Fluorescence studies, ROS modulators, and the use of mutants confirmed the role of guard cell alkalinization for ROS production during ABA- or MA-induced closure. Concanamycin A1, inhibitor of vacuolar H+-ATPase (V-ATPase) restricted the extent of closure by either ABA or MA. The expression patterns of VHA-A3 (V-ATPase subunit) and the response of vha-a3 mutant confirmed that V-ATPase was necessary for cytosolic pH change and ROS production by ABA or MA. The patterns of closure in the presence of varying ABA with or without MA suggested an increased affinity to ABA in the presence of MA. We propose that V-ATPase-mediated increase in cytosolic pH can elevate ROS in guard cells during ABA-induced stomatal closure.