Chitosan-enhanced heat tolerance associated with alterations in antioxidant defense system and gene expression in creeping bentgrass
Qiuguo Li, Yingjie Bian, Ruonan Li, Zhimin Yang, Nanqing Liu, Jingjin Yu
Abstract
As an effective plant growth regulator, chitosan plays a positive role in enhancing heat tolerance in perennial turfgrass. The objective of this study was to elucidate whether chitosan-promoted thermotolerance was associated with the antioxidant defense system under long-term heat stress in creeping bentgrass (<italic>Agrostis stolonifera</italic>). Plants were treated with or without 100 mg∙L<sup>−1</sup> chitosan under either heat stress (38/28 °C, day/night) or non-stressed condition (25/20 °C, day/night) for 42 d in growth chambers. Foliar application of chitosan significantly enhanced heat tolerance as reflected by the increased turf quality through inhibiting over-accumulation of reactive oxygen species, and increasing ascorbic acid content and antioxidant enzymes activities (peroxidase, POD; ascorbate peroxidase, APX; glutathione reductase, GR; dehydroascorbate reductase, DHAR). Chitosan-treated plants also had higher transcript levels of <italic>AsCu/ZnSOD</italic>, <italic>AsCATB</italic>, <italic>AsPerox4</italic>, <italic>AsAPX2</italic>, <italic>AsAPX3</italic>, <italic>AsAPX4</italic>, <italic>AsAPX6</italic>, <italic>AsAPX8</italic>, <italic>AsGR2</italic>, and <italic>AsDHAR</italic> genes in comparison to the untreated plants. The results suggested that chitosan-promotion in heat tolerance could be associated with non-enzymatic antioxidants, antioxidant enzymes, as well as relative gene expression.