AUTHOR=Jin Zhuping , Sun Limin , Yang Guangdong , Pei Yanxi 

TITLE=Hydrogen Sulfide Regulates Energy Production to Delay Leaf Senescence Induced by Drought Stress in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01722

DOI=10.3389/fpls.2018.01722

ISSN=1664-462X

ABSTRACT=<p>Hydrogen sulfide (H<sub>2</sub>S) is a novel gasotransmitter in both mammals and plants. H<sub>2</sub>S plays important roles in various plant developmental processes and stress responses. Leaf senescence is the last developmental stage and is a sequential degradation process that eventually leads to leaf death. A mutation of the H<sub>2</sub>S-producing enzyme-encoding gene <sc>L</sc>-cysteine desulfhydrase1 (<italic>DES1</italic>) leads to premature leaf senescence but the underlying mechanisms are not clear. In this present study, wild-type, <italic>DES1</italic> defective mutant (<italic>des1</italic>) and over-expression (<italic>OE-DES1</italic>) <italic>Arabidopsis</italic> plants were used to investigate the underlying mechanism of H<sub>2</sub>S signaling in energy production and leaf senescence under drought stress. The <italic>des1</italic> mutant was more sensitive to drought stress and displayed accelerated leaf senescence, while the leaves of <italic>OE-DES1</italic> contained adequate chlorophyll levels, accompanied by significantly increased drought resistance. Under drought stress, the expression levels of <italic>ATP</italic>β-<italic>1, -2</italic>, and <italic>-3</italic> were significantly downregulated in <italic>des1</italic> and significantly upregulated in <italic>OE-DES1</italic>, and <italic>ATP</italic>ε showed the opposite trend. Senescence-associated gene (<italic>SAG</italic>) <italic>12</italic> correlated with age-dependent senescence and participated in the drought resistance of <italic>OE-DES1</italic>. <italic>SAG13</italic>, which was induced by environmental factors, responded positively to drought stress in <italic>des1</italic> plants, while there was no significant difference in the <italic>SAG29</italic> expression between <italic>des1</italic> and <italic>OE-DES1</italic>. Using transmission electron microscopy, the mitochondria of <italic>des1</italic> were severely damaged and bubbled in older leaves, while <italic>OE-DES1</italic> had complete mitochondrial structures and a homogeneous matrix. Additionally, mitochondria isolated from <italic>OE-DES1</italic> increased the H<sub>2</sub>S production rate, H<sub>2</sub>S content and ATPase activity level, as well as reduced swelling and lowered the ATP content in contrast with wild-type and <italic>des1</italic> significantly. Therefore, at subcellular levels, H<sub>2</sub>S appeared to determine the ability of mitochondria to regulate energy production and protect against cellular aging, which subsequently delayed leaf senescence under drought-stress conditions in plants.</p>