Bastian Franzisky
Geisenheim University
Beginning with a focus on plant biochemistry and physiology during university studies, I investigated plant stress responses to high light and soil salinity using molecular approaches in Arabidopsis. My research included the characterization of a plastid-localized Ca2+-dependent kinase and the role of two enzyme homologs in proline biosynthesis under salinity. Driven by the desire to apply my knowledge to real-world challenges, I transitioned to crop research to study the effects of salinity on stomatal regulation in field bean.
Title of presentation
Myrosinase TGG1 regulates guard cell glucosinolate levels with significance for drought-related stomatal closure
Authors
B. L. FRANZISKY, G. BÁRDOS, K. WITZEL, F. S. HANSCHEN, B. KROSCHEWSKI, C. ZÖRB, C-M. GEILFUS
Department of Soil Science and Plant Nutrition, Geisenheim University, Von-Lade-Str. 1, 65366 Geisenheim, Germany
Abstract
Myrosinase in guard cells of Brassicaceae is suspected to be involved in the drought response by regulating stomatal closure to minimize water loss. Specifically, THIOGLUCOSIDE GLUCOHYDROLASE1 (TGG1) and TGG2 hydrolyze glucosinolates (GLSs), with the degradation products triggering stomatal closure. We explore the role of TGG1 in drought tolerance in Arabidopsis thaliana by comparing wild-type (Col-0) plants with tgg1-1 mutants under progressive soil desiccation. In tgg1-1 mutants, the drought-induced reduction in stomatal pore area was less pronounced, while relative leaf water content decreased and membrane leakage increased compared to Col-0. These observations suggest that TGG1 is relevant for effective stomatal closure, which is vital for preserving leaf hydration and membrane integrity during drought. Quantitative glucosinolate profiling unveiled similar proportions of alkyl and indol GLSs in guard cells, with higher concentrations of these GLSs in tgg1-1 mutants also under drought, implying a role for TGG1-mediated GLS breakdown in stomatal regulation. These findings underscore the importance of TGG1 for drought tolerance, potentially through GLS breakdown-mediated stomatal closure, and provide new insights into the complex interplay between plant chemical defense and abiotic stress responses.