Cytokinin Effects on Creeping Bentgrass Response to Heat Stress: II. Leaf Senescence and Antioxidant Metabolism

Crop Science ◽  
2002 ◽  
Vol 42 (2) ◽  
pp. 466-472 ◽  
Author(s):  
Xiaozhong Liu ◽  
Bingru Huang
Keyword(s):  
Heat Stress ◽  
Leaf Senescence ◽  
Creeping Bentgrass ◽  
Antioxidant Metabolism

scholarly journals Chitosan (CTS) Alleviates Heat-Induced Leaf Senescence in Creeping Bentgrass by Regulating Chlorophyll Metabolism, Antioxidant Defense, and the Heat Shock Pathway

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5337
Author(s):  
Cheng Huang ◽  
Yulong Tian ◽  
Bingbing Zhang ◽  
Muhammad Jawad Hassan ◽  
Zhou Li ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Leaf Senescence ◽  
Heat Tolerance ◽  
Antioxidant Defense ◽  
Creeping Bentgrass ◽  
Grass Species ◽  
Antioxidant Enzyme Activities ◽  
Ros Scavenging ◽  
Chlorophyll Metabolism

Chitosan (CTS) is a deacetylated derivative of chitin that is involved in adaptive response to abiotic stresses. However, the regulatory role of CTS in heat tolerance is still not fully understood in plants, especially in grass species. The aim of this study was to investigate whether the CTS could reduce heat-induced senescence and damage to creeping bentgrass associated with alterations in antioxidant defense, chlorophyll (Chl) metabolism, and the heat shock pathway. Plants were pretreated exogenously with or without CTS (0.1 g L−1) before being exposed to normal (23/18 °C) or high-temperature (38/33 °C) conditions for 15 days. Heat stress induced detrimental effects, including declines in leaf relative water content and photochemical efficiency, but significantly increased reactive oxygen species (ROS) accumulation, membrane lipid peroxidation, and Chl loss in leaves. The exogenous application of CTS significantly alleviated heat-induced damage in creeping bentgrass leaves by ameliorating water balance, ROS scavenging, the maintenance of Chl metabolism, and photosynthesis. Compared to untreated plants under heat stress, CTS-treated creeping bentgrass exhibited a significantly higher transcription level of genes involved in Chl biosynthesis (AsPBGD and AsCHLH), as well as a lower expression level of Chl degradation-related gene (AsPPH) and senescence-associated genes (AsSAG12, AsSAG39, Asl20, and Ash36), thus reducing leaf senescence and enhancing photosynthetic performance under heat stress. In addition, the foliar application of CTS significantly improved antioxidant enzyme activities (SOD, CAT, POD, and APX), thereby effectively reducing heat-induced oxidative damage. Furthermore, heat tolerance regulated by the CTS in creeping bentgrass was also associated with the heat shock pathway, since AsHSFA-6a and AsHSP82 were significantly up-regulated by the CTS during heat stress. The potential mechanisms of CTS-regulated thermotolerance associated with other metabolic pathways still need to be further studied in grass species.

scholarly journals Suppression of Shade- or Heat-induced Leaf Senescence in Creeping Bentgrass through Transformation with the ipt Gene for Cytokinin Synthesis

2009 ◽  
Vol 134 (6) ◽  
pp. 602-609 ◽  
Author(s):  
Jinpeng Xing ◽  
Yan Xu ◽  
Jiang Tian ◽  
Thomas Gianfagna ◽  
Bingru Huang
Keyword(s):  
Heat Stress ◽  
Chlorophyll Content ◽  
Leaf Senescence ◽  
Creeping Bentgrass ◽  
Grass Species ◽  
Control Line ◽  
Dark Treatment ◽  
Transgenic Lines ◽  
Cytokinin Synthesis ◽  
Whole Plants

Cytokinins have been associated with delaying or suppressing leaf senescence in plants. The objectives of this study were to determine whether the expression of the ipt gene that encodes adenine isopentenyltransferase would delay leaf senescence induced by shade or heat stress in a perennial grass species. Creeping bentgrass (Agrostis stolonifera cv. Penncross) was transformed with ipt isolated from agrobacterium (Agrobacterium tumefaciens) using two gene constructs (SAG12-ipt and HSP18-ipt) designed to activate cytokinin synthesis during shade or heat stress. Whole plants of nine SAG12-ipt transgenic lines and the nontransgenic control plants were incubated in darkness at 20 °C for 20 days. Chlorophyll content of all transgenic lines and the control line decreased after dark treatment, but the decline was less pronounced in transgenic lines. All transgenic lines had higher isopentenyladenine (iP/iPA) content than the control line after 20 days of treatment. In six of the transgenic lines, iP/iPA content remained the same or higher after dark treatment. Whole plants of nine HSP18-ipt transgenic lines and the control plants were incubated at 35 °C for 7 days. Chlorophyll and iP/iPA content declined in the control plants, but the nine transgenic lines had a significantly higher concentration of iP/iPA and were able to maintain chlorophyll content at the prestress level. Our results suggest that expression of SAG12-ipt or HSP18-ipt in creeping bentgrass resulted in increases in cytokinin production, which may have led to the delay and suppression of leaf senescence induced by shade or heat stress.

scholarly journals Sitosterol-mediated Antioxidant Regulation to Enhance Heat Tolerance in Creeping Bentgrass

2022 ◽  
Vol 147 (1) ◽  
pp. 18-24
Author(s):  
Stephanie Rossi ◽  
Bingru Huang
Keyword(s):  
Heat Stress ◽  
Leaf Senescence ◽  
Heat Tolerance ◽  
Foliar Application ◽  
Creeping Bentgrass ◽  
Membrane Lipid ◽  
Membrane Stability ◽  
Turf Quality ◽  
Mda Content ◽  
Plant Metabolite

Heat stress symptoms in cool-season plants are characterized by loss of chlorophyll (Chl) and membrane stability, as well as oxidative damage. The objectives of this study were to determine whether foliar application of β-sitosterol, a naturally occurring plant metabolite, may promote heat tolerance by suppressing heat-induced leaf senescence as indicated by the maintenance of healthy turf quality (TQ), and Chl and membrane stability; and to determine its roles in regulating antioxidant metabolism in creeping bentgrass (Agrostis stolonifera). ‘Penncross’ plants were exposed to heat stress (35/30 °C day/night) optimal temperature conditions (nonstressed control, 22/17 °C day/night) for a duration of 28 days in environment-controlled growth chambers. Plants were foliar-treated with β-sitosterol (400 µM) or water only (untreated control) before heat stress, and at 7-day intervals through 28 days of heat stress. Plants treated with β-sitosterol had significantly greater TQ and Chl content, and significantly less electrolyte leakage (EL) than untreated controls at 21 and 28 days of heat stress. Application of β-sitosterol reduced malondialdehyde (MDA) content significantly at 21 and 28 days of heat stress, and promoted the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) from 14 through 28 days of heat stress. β-Sitosterol effectively improved heat tolerance through suppression of leaf senescence in creeping bentgrass exposed to heat stress in association with the alleviation of membrane lipid peroxidation and activation of the enzymatic antioxidant system.

scholarly journals Heat-induced Leaf Senescence and Hormonal Changes for Thermal Bentgrass and Turf-type Bentgrass Species Differing in Heat Tolerance

2007 ◽  
Vol 132 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Yan Xu ◽  
Bingru Huang
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Leaf Senescence ◽  
Heat Tolerance ◽  
Photochemical Efficiency ◽  
Creeping Bentgrass ◽  
Zeatin Riboside ◽  
Hormonal Changes ◽  
Heat Tolerant ◽  
Aba Content

Leaf senescence can be induced by many environmental stresses, including supraoptimal temperatures. The objectives of this study were to evaluate leaf senescence induced by heat stress for two Agrostis species contrasting in heat tolerance and to examine whether heat-induced leaf senescence in both species was associated with changes in three major senescence-related hormones: ethylene, abscisic acid (ABA), and cytokinins. Plants of heat-tolerant rough bentgrass (Agrostis scabra Willd.) and heat-sensitive creeping bentgrass (Agrostis stolonifera L.) were exposed to 35/30 °C (day/night) (high temperature) or 20/15 °C (control) for 35 d in growth chambers. Turf quality, photochemical efficiency (Fv/Fm), and the contents of two pigments (chlorophyll and carotenoid) for both species decreased under high temperature; however, heat-tolerant A. scabra exhibited delayed and less severe decline in all parameters compared with heat-sensitive A. stolonifera. Ethylene production rate increased in both species at 35 °C, but the increase was observed 21 days later in A. scabra compared with that in A. stolonifera. ABA content increased at the initiation of heat stress and then declined in both species after prolonged heat stress. However, the timing of the increase was delayed for 7 days and the highest level of ABA content was less in A. scabra (4.0 times that of the control) than that in A. stolonifera (5.9 times that of the control). Decreases in both forms of cytokinins (transzeatin/zeatin riboside and isopentenyl adenosine) were also delayed for 14 days and less pronounced in A. scabra. Correlation analysis revealed that leaf senescence induced by heat stress was negatively correlated to ethylene and ABA accumulation and positively correlated to cytokinin production. Delayed leaf senescence in A. scabra under heat stress could be related to slower and less magnitude of changes in ethylene, ABA, and cytokinins.

scholarly journals Leaf Senescence and Protein Metabolism in Creeping Bentgrass Exposed to Heat Stress and Treated with Cytokinins

2007 ◽  
Vol 132 (4) ◽  
pp. 467-472 ◽  
Author(s):  
Mahalaxmi Veerasamy ◽  
Yali He ◽  
Bingru Huang
Keyword(s):  
Heat Stress ◽  
Protein Content ◽  
Leaf Senescence ◽  
Protein Metabolism ◽  
Soluble Protein ◽  
Protease Activity ◽  
Creeping Bentgrass ◽  
Zeatin Riboside ◽  
Soluble Protein Content ◽  
Leaf Chlorophyll

Heat stress induces leaf senescence and causes changes in protein metabolism. The objective of this study was to investigate effects of exogenous application of a synthetic form of cytokinin, zeatin riboside (ZR), on protein metabolism associated with leaf senescence under heat stress for a cool-season grass species. Creeping bentgrass (Agrostis stolonifera L.) (cv. Penncross) plants were exposed to optimum temperature control (20/15 °C, day/night) and heat stress (35/30 °C) in growth chambers. Before heat stress treatments, foliage was sprayed with 10 μmol ZR or water (untreated) for 3 days and then once per week during 35 days of heat stress. Leaf chlorophyll content, photochemical efficiency (Fv/Fm), and soluble protein content declined, whereas protease activity increased during heat stress. Treatments with ZR helped maintain higher leaf chlorophyll content, Fv/Fm, and soluble protein content under heat stress. Protease activity in ZR-treated plants was lower than that of untreated plants. Zeatin riboside-treated plants had less severe degradation of ribulose-1,5-bisphosphate carboxylase proteins than untreated plants exposed to heat stress. In addition, ZR treatment upregulated the expression of 32- and 57-kDa proteins under heat stress conditions. These results demonstrated that the exogenous application of ZR ameliorated the negative effects of heat stress, as manifested by suppression or delay of leaf senescence. Cytokinins may have helped to alleviate heat stress injury, probably by slowing down the action of protease and by induction or upregulation of heat-shock proteins.

Cytokinin Effects on Creeping Bentgrass Responses to Heat Stress: I. Shoot and Root Growth

Crop Science ◽  
2002 ◽  
Vol 42 (2) ◽  
pp. 457-465 ◽  
Author(s):  
Xiaozhong Liu ◽  
Bingru Huang ◽  
Gary Banowetz
Keyword(s):  
Heat Stress ◽  
Root Growth ◽  
Creeping Bentgrass ◽  
Shoot And Root Growth

scholarly journals SMRT and Illumina RNA sequencing reveal novel insights into the heat stress response and crosstalk with leaf senescence in tall fescue

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Yiguang Qian ◽  
Liwen Cao ◽  
Qiang Zhang ◽  
Maurice Amee ◽  
Ke Chen ◽  
...  
Keyword(s):  
Heat Stress ◽  
Stress Response ◽  
Rna Sequencing ◽  
Leaf Senescence ◽  
Tall Fescue ◽  
Heat Stress Response
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