AUTHOR=Xia Zongliang , Huo Yongjin , Wei Yangyang , Chen Qiansi , Xu Ziwei , Zhang Wei 

TITLE=The Arabidopsis LYST INTERACTING PROTEIN 5 Acts in Regulating Abscisic Acid Signaling and Drought Response

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00758

DOI=10.3389/fpls.2016.00758

ISSN=1664-462X

ABSTRACT=<p>Multivesicular bodies (MVBs) are unique endosomes containing vesicles in the lumens and play essential roles in many eukaryotic cellular processes. The <italic>Arabidopsis</italic> LYST INTERACTING PROTEIN 5 (LIP5), a positive regulator of MVB biogenesis, has critical roles in biotic and abiotic stress responses. However, whether the abscisic acid (ABA) signaling is involved in LIP5-mediated stress response is largely unknown. Here, we report that <italic>LIP5</italic> functions in regulating ABA signaling and drought response in <italic>Arabidopsis</italic>. Analyses of a <italic>LIP5</italic> promoter-β-glucuronidase (<italic>GUS</italic>) construct revealed substantial GUS activity in whole seedlings. The expression of <italic>LIP5</italic> was induced by ABA and drought, and overexpression of <italic>LIP5</italic> led to ABA hypersensitivity, enhanced stomatal closure, reduced water loss, and, therefore, increased drought tolerance. On the contrary, <italic>LIP5</italic> knockdown mutants showed ABA-insensitive phenotypes and reduced drought tolerance; suggesting that <italic>LIP5</italic> acts in regulating ABA response. Further analysis using a fluorescent dye revealed that ABA and water stress induced cell endocytosis or vesicle trafficking in a largely LIP5-dependent manner. Furthermore, expression of several drought- or ABA-inducible marker genes was significantly down-regulated in the <italic>lip5</italic> mutant seedlings. Collectively, our data suggest that <italic>LIP5</italic> positively regulates drought tolerance through ABA-mediated cell signaling.</p>