AUTHOR=Dai Cheng , Lee Yuree , Lee In C. , Nam Hong G. , Kwak June M. 

TITLE=Calmodulin 1 Regulates Senescence and ABA Response in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00803

DOI=10.3389/fpls.2018.00803

ISSN=1664-462X

ABSTRACT=<p>Cellular calcium acts as a second messenger and regulates diverse developmental events and stress responses. Cytosolic calcium has long been considered as an important regulator of senescence, however, the role of Ca<sup>2+</sup> in plant senescence has remained elusive. Here we show that the <italic>Calmodulin 1</italic> (<italic>CaM1</italic>) gene, which encodes Ca<sup>2+</sup>-binding protein calmodulin 1, positively regulates leaf senescence in <italic>Arabidopsis</italic>. Yellowing of leaves, accumulation of reactive oxygen species (ROS), and expression of the <italic>senescence-associated gene 12</italic> (<italic>SAG12</italic>) were significantly enhanced in <italic>CaM1</italic> overexpression plants. In contrast, abscisic acid (ABA)-triggered ROS production and stomatal closure were reduced in <italic>amiRNA-CaM1</italic> plants. We found a positive-feedback regulation loop among three signaling components, CaM1, RPK1, and RbohF, which physically associate with each other. RPK1 positively regulates the expression of the <italic>CaM1</italic> gene, and the CaM1 protein, in turn, up-regulates <italic>RbohF</italic> gene expression. Interestingly, the expression of <italic>CaM1</italic> was down-regulated in <italic>rbohD, rbohF</italic>, and <italic>rbohD/F</italic> mutants. We show that CaM1 positively regulates ROS production, leaf senescence, and ABA response in <italic>Arabidopsis</italic>.</p>