AUTHOR=Wang Shu-Min , Wang You-Shao , Su Bo-Yu , Zhou Yue-Yue , Chang Li-Fang , Ma Xiao-Yu , Li Xiao-Mei 

TITLE=Ecophysiological Responses of Five Mangrove Species (Bruguiera gymnorrhiza, Rhizophora stylosa, Aegiceras corniculatum, Avicennia marina, and Kandelia obovata) to Chilling Stress

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.846566

DOI=10.3389/fmars.2022.846566

ISSN=2296-7745

ABSTRACT=<p>Although the low temperature is a critical growth constraint on plants, the physiological mechanism remains unclear, especially in mangrove plants. Hence, the morphological characteristics of five mangrove plants (<italic>Bruguiera gymnorrhiza</italic>, <italic>Rhizophora stylosa</italic>, <italic>Aegiceras corniculatum</italic>, <italic>Avicennia marina</italic>, and <italic>Kandelia obovata</italic>) were compared under chilling stress. The contents of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), malondialdehyde (MDA), and proline were tested. Activities of reactive oxygen species (ROS)-scavenging enzyme [superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)] were also measured after chilling stress. It was concluded that <italic>K. obovata</italic> can well tolerate chilling stress, and <italic>B. gymnorrhiza</italic> suffered the most severe chilling damage. Leaf-morphology observation exhibited that <italic>K. obovata</italic> and <italic>A. corniculatum</italic> can sustain chilling stress, while <italic>B. gymnorrhiza</italic> wilted and <italic>A. marina</italic> turned brown. The content of H<sub>2</sub>O<sub>2</sub> increased at first and subsequently decreased in all plants. MDA increased instantaneously in <italic>B. gymnorrhiza</italic> and <italic>R. stylosa</italic> but changed slowly in <italic>K. obovata</italic> and <italic>A. corniculatum</italic>. The high content of proline accumulated in <italic>B. gymnorrhiza</italic> and <italic>K. obovata</italic>. The activities of the SOD, POD, and CAT increased at first and then decreased in all mangrove species. The antioxidants maintained high activity in <italic>K. obovata</italic> while decreasing earliest in <italic>A. marina</italic> exposed to the long-term chilling stress. Principal component analysis (PCA) indicated that high antioxidant enzyme activities play key roles in chilling tolerance for mangrove plants. The longer-term chilling tolerance of <italic>K. obovata</italic> may be related to the high antioxidant enzyme activities and proline accumulation. Lower H<sub>2</sub>O<sub>2</sub> and MDA contents strengthen the anti-chilling ability of <italic>A. corniculatum.</italic> Further investigation on the molecular mechanisms will facilitate the understanding of the anti-chilling ability of mangrove plants.</p>