Antioxidant and Hormone Responses to Heat Stress in Two Kentucky Bluegrass Cultivars Contrasting in Heat Tolerance

Heat stress is a major limiting factor for growth of cool-season perennial grass species, and mechanisms of heat tolerance have not been well understood. This study was designed to investigate antioxidant enzyme and hormone metabolism responses to heat stress in two kentucky bluegrass (Poa pratensis L.) cultivars contrasting in heat tolerance. The plants were subjected to 20/20 °C [day/night (control)] or 38/30 °C [day/night (heat stress)] for 28 days in growth chambers. Heat stress increased leaf electrolyte leakage (EL) and malondialdehyde (MDA) with heat-tolerant cultivar EverGlade exhibiting lower levels of EL and MDA relative to heat-sensitive cultivar Kenblue under heat stress. Superoxide dismutase (SOD) and catalase (CAT) activity increased and then declined during 28 days of heat stress. Peroxidase (POD) and ascorbate peroxidase (APX) activity declined and then increased during heat stress. ‘EverGlade’ had greater activities of SOD, CAT, POD, and APX relative to ‘Kenblue’ under heat stress. In addition, ‘EverGlade’ had two additional SOD isozymes and three additional POD isozymes relative to ‘Kenblue’ under heat stress. Leaf abscisic acid (ABA) increased in response to heat stress. Leaf indole-3-acetic acid (IAA) increased and then declined during heat stress. ‘OverGlade’ had higher ABA and IAA content relative to ‘Kenblue’. At the end of heat stress, leaf IAA and ABA content were 27.8% and 73% higher in ‘EverGlade’ relative to ‘Kenblue’, respectively. The results indicated that antioxidant enzymes and the hormones (ABA and IAA) were associated with kentucky bluegrass heat tolerance. Selection and use of cultivars with higher IAA and ABA content and greater antioxidant enzyme activities may improve kentucky bluegrass growth and quality under heat stress.

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Antioxidant Enzyme Activities and Gene Expression Patterns in Leaves of Kentucky Bluegrass in Response to Drought and Post-drought Recovery

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.136.4.247 ◽

2011 ◽

Vol 136 (4) ◽

pp. 247-255 ◽

Cited By ~ 49

Author(s):

Lixin Xu ◽

Liebao Han ◽

Bingru Huang

Keyword(s):

Gene Expression ◽

Drought Stress ◽

Antioxidant Enzyme ◽

Water Deficit ◽

Poa Pratensis ◽

Kentucky Bluegrass ◽

Grass Species ◽

Antioxidant Enzyme Activities ◽

Guaiacol Peroxidase ◽

Drought Recovery

The objectives of this study were to examine antioxidant enzyme responses to drought stress and rewatering at both enzymatic activity and transcript levels and to determine the major antioxidant processes associated with drought tolerance and post-drought recovery for a perennial grass species, kentucky bluegrass (Poa pratensis). Antioxidant enzyme responses to drought and rewatering in a drought-tolerant cultivar (Midnight) and a drought-sensitive cultivar (Brilliant) were compared in a growth chamber. Plants were exposed to 22 days of drought stress for ‘Midnight’ and 18 days for ‘Brilliant’ before rewatering to allow the leaf relative water content (RWC) of both cultivars to drop to the same level. ‘Midnight’ exhibited higher photochemical efficiency (Fv/Fm) and lower electrolyte leakage compared with ‘Brilliant’ when at the same water deficit status (26% to 28% RWC). After 6 days of rewatering, all physiological parameters returned to the control level for ‘Midnight’, but only Fv/Fm fully recovered for ‘Brilliant’. The transcript level of cytosolic copper/zinc superoxide dismutase (cyt Cu/Zn SOD) and ascorbate peroxidase (APX) was significantly higher in ‘Midnight’ than in ‘Brilliant’ when exposed to the same level of water deficit (26% to 28% RWC), suggesting that SOD and APX could be involved in scavenging oxidative stress-induced reactive oxygen species in kentucky bluegrass through changes in the level of gene expression. Significantly higher activities of APX, monodehydroascorbate reductase, glutathione reductase, and dehydroascorbate reductase as well as lower lipid peroxidation levels were observed in ‘Midnight’ versus ‘Brilliant’ when exposed to drought. However, the activities of SOD, catalase (CAT), and guaiacol peroxidase (POD) did not differ between the two cultivars. After 6 days of rewatering, ‘Midnight’ displayed significantly higher activity levels of CAT, POD, and APX compared with ‘Brilliant’. The enzyme activity results indicate that enzymes involved in the ascorbate–glutathine cycle may play important roles in antioxidant protection to drought damage, whereas CAT, POD, and APX could be associated with better post-drought recovery in kentucky bluegrass.

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Differential Responses of Nutrients to Heat Stress in Warm-season and Cool-season Turfgrasses

HortScience ◽

10.21273/hortsci.44.7.2009 ◽

2009 ◽

Vol 44 (7) ◽

pp. 2009-2014 ◽

Cited By ~ 12

Author(s):

Hua Shen ◽

Hongmei Du ◽

Zhaolong Wang ◽

Bingru Huang

Keyword(s):

Heat Stress ◽

Heat Tolerance ◽

Poa Pratensis ◽

Warm Season ◽

Kentucky Bluegrass ◽

Grass Species ◽

Cool Season ◽

Temperature Conditions ◽

Differential Responses ◽

K Concentration

The objective of this study was to compare differential nutrient responses to heat stress in relation to heat tolerance for warm-season (C4) common bermudagrass [Cynodon dactylon (L.) Pers.] and cool-season (C3) kentucky bluegrass (Poa pratensis L.). Both species were exposed to two temperature regimes in growth chambers: optimal day/night temperature conditions (24/20 °C for kentucky bluegrass and 34/30 °C for bermudagrass) or heat stress (10 °C above the respective optimal temperature for each species). Heat injury in leaves was evaluated and the concentrations of several major macronutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] in both grass species were measured at 0, 7, 14, 21, and 28 days of treatment. Heat stress reduced leaf photochemical efficiency and cellular membrane stability in both species, but bermudagrass leaves exhibited less damage in these parameters than kentucky bluegrass. Heat stress caused a significant decline in N, P, and K concentration, beginning at 7 days in kentucky bluegrass, but had no significant effects on N, P, and K concentration in bermudagrass during the 28-day treatment period. The concentration of Ca and Mg increased under heat stress in both kentucky bluegrass and bermudagrass, but there were no significant differences between the species under optimal or high-temperature conditions, suggesting they were not involved in heat responses in either species. The differential responses of N, P, and K to heat stress could at least partially account for the differences in heat tolerance between the two species and demonstrate the importance of sufficient N, P, and K in turfgrass adaptation to heat stress.

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

Molecules ◽

10.3390/molecules26175337 ◽

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.

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Differential Responses to Heat Stress in Activities and Isozymes of Four Antioxidant Enzymes for Two Cultivars of Kentucky Bluegrass Contrasting in Heat Tolerance

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.135.2.116 ◽

2010 ◽

Vol 135 (2) ◽

pp. 116-124 ◽

Cited By ~ 26

Author(s):

Yali He ◽

Bingru Huang

Keyword(s):

Antioxidant Enzymes ◽

Heat Stress ◽

Heat Tolerance ◽

Defense Mechanisms ◽

Poa Pratensis ◽

Kentucky Bluegrass ◽

Guaiacol Peroxidase ◽

Cool Season ◽

Chl A ◽

Antioxidant Mechanisms

Understanding antioxidant mechanisms for heat stress is important for improving heat tolerance in cool-season plant species. The objective of this study was to identify antioxidant enzymes associated with cultivar variations in heat tolerance in kentucky bluegrass (Poa pratensis) by comparing heat responses of activity and isoforms of antioxidant enzymes in two cultivars contrasting in heat tolerance. Plants of heat-tolerant ‘Eagleton’ and heat-sensitive ‘Brilliant’ were exposed to 20 °C (control) or 40 °C (heat stress) for 28 days in growth chambers. Chlorophyll (Chl) a content remained unchanged and Chl b content increased in ‘Eagleton’, while both of them decreased in ‘Brilliant’, and by 28 days, ‘Eagleton’ had significantly higher Chl a and b content than ‘Brilliant’. The activities of superoxide dismutase (SOD) were significantly higher in ‘Eagleton’ than in ‘Brilliant’ by 28 days of heat stress. An isozyme SOD2 was induced early during heat stress in ‘Eagleton’, while isozyme SOD3 degraded, to a lesser extent in ‘Eagleton’ than in ‘Brilliant’. Catalase (CAT) activity significantly increased in ‘Brilliant’ but remained constant in ‘Eagleton’, and ‘Brilliant’ had a significantly higher CAT activity and isozyme CAT1 than ‘Eagleton’ during heat stress. Significant increases in ascorbate peroxidase (APX) activities occurred under heat stress, to a greater extent in ‘Eagleton’, whereas isozymes did not exhibit difference between cultivars. Guaiacol-peroxidase (POD) activity declined during heat stress in both cultivars. The intensity of POD isozymes in ‘Brilliant’ remained constant, while ‘Eagleton’ showed a transient increases in POD1 at 7 days of heat stress. Our results indicated that antioxidant defense mechanisms for heat tolerance in kentucky bluegrass could be mainly associated with changes in activity and forms of isozymes of SOD for O2 scavenging and APX activity for H2O2 scavenging under heat stress.

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Silvertop in perennial grass seed production: Effects of type and timing of biotic stresses

Canadian Journal of Plant Science ◽

10.1139/cjps-2020-0243 ◽

2021 ◽

Author(s):

Julie Soroka ◽

Bruce D. Gossen

Keyword(s):

Seed Production ◽

Poa Pratensis ◽

Perennial Grass ◽

Kentucky Bluegrass ◽

Development Stage ◽

Perennial Grasses ◽

Grass Species ◽

Biotic Stresses ◽

Seed Harvest ◽

Bromus Riparius

Seed production of perennial grasses is an important industry in Canada, but many fields exhibit high proportions of sterile heads with characteristic symptoms in a condition known as silvertop. In a 3-yr field study, biotic stress treatments were applied to caged plots of Kentucky bluegrass (Poa pratensis) and meadow bromegrass (Bromus riparius) to assess their effects on silvertop incidence. Treatments were: 1) control, 2) addition of grass-feeding insects, primarily grass plant bugs (Miridae), 3) inoculation with Fusarium poae spores, 4) both insects and spores, and in one year, 5) mechanical piercing of seed heads above the last node. Additionally, cores of the two grass species were potted and removed from the field in spring in each of 2 years. After 2-, 4-, and 6-wk intervals in a cold room at 4° C to stagger plant development stage, the five treatments were applied to caged plants of both grasses, which were maintained in a greenhouse until seed harvest. In both studies, the numbers of healthy seed heads, percentage of heads with silvertop, and seed weights were determined. In the field, stress treatments infrequently and inconsistently affected silvertop levels. Regression showed that the relationship between silvertop and seed yield, although significant, explained little of the variability in yield. Silvertop developed in all treatments in the greenhouse; treatments had no effect on silvertop levels, which were highest in plants treated at the R1 (boot) growth stage. This suggests that the boot stage of the two grass species is most vulnerable to silvertop occurrence.

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Enhanced antioxidant enzyme activities in developing anther contributes to heat stress alleviation and sustains grain yield in wheat

Functional Plant Biology ◽

10.1071/fp19016 ◽

2019 ◽

Vol 46 (12) ◽

pp. 1090 ◽

Cited By ~ 3

Author(s):

Sharad K. Dwivedi ◽

Sahana Basu ◽

Santosh Kumar ◽

Surbhi Kumari ◽

Alok Kumar ◽

...

Keyword(s):

Heat Stress ◽

Grain Yield ◽

Antioxidant Enzyme ◽

Heat Tolerance ◽

Enzyme Activities ◽

Redox Homeostasis ◽

Antioxidant Enzyme Activities ◽

Ros Scavenging ◽

Wheat Genotype ◽

Wheat Genotypes

Climatic variations along with a rise in temperature during the winter season impose severe heat stress during the anthesis stage of spring wheat, resulting in severe yield losses. The present study was conducted to evaluate the influence of heat stress on redox homeostasis in developing anthers and flag leaves of wheat. Five Indian bread wheat genotypes were studied under field conditions during the dry season, with two extreme sowing dates (timely and very late sown) to explore the effect of heat stress on anthesis stage. Results showed that elevated temperature during anthesis caused significant increase in reactive oxygen species (ROS) content and malondialdehyde (MDA) accumulation in developing anthers, triggering pollen mortality. Moreover, defective source (leaf) to the sink (anthers) mobilisation of starch also contributes in reducing pollen viability. However, ROS-induced oxidative damage of developing anthers under heat stress varied among the wheat genotypes depending upon differential antioxidant enzyme activities. Wheat genotype with enhanced antioxidant activities and reduced ROS built up in developing anthers sustained their grain yield, suggesting thermo-tolerance in wheat to be associated with antioxidant enzyme-mediated improved ROS-scavenging mechanism not only in leaves even in developing anther also. In the present study, heat stressed wheat genotype WH 730 exhibited effective source to sink mobilisation and sustainable grain yield with improved ROS scavenging, conferring greater potential for heat tolerance. We conclude that redox homeostasis and balanced source sink activity played a significant role for sustainable yield and heat tolerance in wheat.

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Differential Effectiveness of Doubling Ambient Atmospheric CO2 Concentration Mitigating Adverse Effects of Drought, Heat, and Combined Stress in Kentucky Bluegrass

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.139.4.364 ◽

2014 ◽

Vol 139 (4) ◽

pp. 364-373

Author(s):

Yali Song ◽

Bingru Huang

Keyword(s):

Heat Stress ◽

Poa Pratensis ◽

Relative Effectiveness ◽

Kentucky Bluegrass ◽

Grass Species ◽

Combined Stress ◽

Cool Season ◽

Positive Effects ◽

Effects Of Drought ◽

Drought And Heat Stress

Drought and heat stress can limit the growth of cool-season grass species, whereas doubling ambient CO2 has been shown to promote plant growth. The objectives of this study were to examine differential responses of shoot and root growth as well as photosynthesis and respiration to doubling ambient CO2 during drought or heat stress alone or the two stresses combined and to determine the relative effectiveness of doubling ambient CO2 in mitigating negative effects of drought or heat stress alone and in combination in a cool-season perennial grass species. Kentucky bluegrass (Poa pratensis cv. Baron) plants were exposed to ambient CO2 (400 μL·L−1) or doubling ambient CO2 (800 μL·L−1) concentrations while subjected to the following stress treatments in growth chambers: drought stress by withholding irrigation, heat stress (35 °C), or the combined two stresses for 28 days. Doubling ambient CO2 increased root and shoot growth as well as root/shoot ratio under all treatments. Doubling ambient CO2 enhanced leaf net photosynthetic rate (Pn) to a greater extent under drought or heat alone, whereas it reduced respiration rate (R), to a larger degree under heat and the combined stress, leading to a greater ratio of Pn/R. Doubling ambient CO2 mitigated adverse physiological effects of drought or heat stress alone, whereas fewer effects were observed under the combined drought and heat stress. The positive effects of doubling ambient CO2 were associated with the development of roots biomass and the maintenance of a positive carbon balance under either stress alone or the combined drought and heat stress.

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Heat Tolerance of Kentucky Bluegrass as Affected by Trinexapac-ethyl

HortScience ◽

10.21273/hortsci.36.2.365 ◽

2001 ◽

Vol 36 (2) ◽

pp. 365-367 ◽

Cited By ~ 8

Author(s):

Neil L. Heckman ◽

Garald L. Horst ◽

Roch E. Gaussoin ◽

Linda J. Young

Keyword(s):

Heat Stress ◽

Heat Tolerance ◽

Vapor Pressure Deficit ◽

Poa Pratensis ◽

Acid Methyl Ester ◽

Kentucky Bluegrass ◽

Single Application ◽

Heat Accumulation ◽

Lethal Temperatures ◽

Acid Methyl

Heat accumulation during storage of sod may reach lethal temperatures within 4 days, decreasing sod quality. Treatment with trinexapac-ethyl reduces heat accumulation during sod storage. However, heat tolerance of grasses treated with trinexapacethyl has not been documented. Our objectives were to: 1) determine the lethal temperatures for Kentucky bluegrass (Poa pratensis L.); and 2) identify the effect of a single application of trinexapac-ethyl on heat tolerance. Experimental design was a randomized complete block with three replications and a two (trinexapac-ethyl vs. control) × two (cultivars) factorial arrangement of treatments. Ten days after chemical treatment, Kentucky bluegrass sprigs were exposed to heat stress for 4 days in a temperature gradient block under low vapor pressure deficit. Treatment with trinexapac-ethyl at 0.23 kg·ha-1 reduced heat tolerance. Temperature needed to kill 50% of the population was 35.5 °C for treated vs. 36.1 °C for nontreated grass. Trinexapac-ethyl is in the same chemical family as the cyclohexanedione herbicides that interfere with lipid syntheses in grasses. This may be a reason for the slight decrease in heat tolerance. The practical value of trinexapac-ethyl treatment in reducing heat accumulation during storage of sod may be partially negated by a decrease in heat tolerance. Chemical name used: [(4-cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid methyl ester] (trinexapac-ethyl).

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Differential Responses of Hybrid Bluegrass and Kentucky Bluegrass to Drought and Heat Stress

HortScience ◽

10.21273/hortsci.43.7.2191 ◽

2008 ◽

Vol 43 (7) ◽

pp. 2191-2195 ◽

Cited By ~ 10

Author(s):

Eleni M. Abraham ◽

William A. Meyer ◽

Stacy A. Bonos ◽

Bingru Huang

Keyword(s):

Heat Stress ◽

Heat Tolerance ◽

Transpiration Rate ◽

Soil Depth ◽

Poa Pratensis ◽

Kentucky Bluegrass ◽

Optimal Temperature ◽

Turf Quality ◽

Differential Responses ◽

Drought And Heat Stress

This study was designed to investigate differential responses of hybrids from Texas bluegrass (Poa arachnifera Torr.) × Kentucky bluegrass (Poa pratensis L.) (KBG) and KBG genotypes to drought and heat stress. Plants of two hybrids, ‘845’ and ‘BDF’, and two KBG genotypes (‘Midnight’ and ‘C-74’) were grown under optimal temperature (22/18 °C) and well-watered (control) or unwatered (drought) or superoptimal temperatures (35/30 °C; heat stress) conditions for 35 days in growth chambers. Under optimal conditions, the two hybrids and two KBG genotypes were not significantly different in turf quality, leaf photochemical efficiency expressed as chlorophyll fluorescence ratio (Fv/Fm), leaf net photosynthetic rate (Pn), transpiration rate, water use efficiency (WUE), root dry matter, or root viability. The results suggest that the interspecific hybridization resulted in similar growth and physiological traits in the hybrid bluegrass as in a turf-type species under optimal temperature and irrigation regimes. Under drought stress, all these parameters were comparable to those for KBG ‘Midnight’, but significantly higher than the corresponding parameters for KBG ‘C-74’. Under heat stress, both hybrids had significantly higher turf quality, Fv/Fm, Pn, transpiration rate, WUE, root dry weight in deeper soil depth (40 to 60 cm), and root viability in the upper 40-cm layer compared with both KBG genotypes. These results suggested that hybrid bluegrass exhibited improvement in drought and heat tolerance, particularly in comparison with KBG ‘C-74’, but to a great extent for heat tolerance. The maintenance of higher transpiration and photosynthesis, WUE, and root viability was associated with the improvement in heat tolerance in hybrid bluegrass.

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Growth and Physiological Traits Associated with Drought Survival and Post-drought Recovery in Perennial Turfgrass Species

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.135.2.125 ◽

2010 ◽

Vol 135 (2) ◽

pp. 125-133 ◽

Cited By ~ 35

Author(s):

Qi Chai ◽

Fang Jin ◽

Emily Merewitz ◽

Bingru Huang

Keyword(s):

Cell Wall ◽

Drought Stress ◽

Osmotic Adjustment ◽

Perennial Grass ◽

Kentucky Bluegrass ◽

Physiological Traits ◽

Grass Species ◽

Cell Wall Elasticity ◽

Drought Recovery ◽

Drought Survival

The objective of this study was to determine physiological traits for drought survival and post-drought recovery upon re-watering in two C3 perennial grass species, kentucky bluegrass [KBG (Poa pratensis)] and perennial ryegrass [PRG (Lolium perenne)]. Plants were maintained well watered or exposed to drought stress by withholding irrigation and were then re-watered in a growth chamber. KBG had significantly higher grass quality and leaf photochemical efficiency, and lower electrolyte leakage than PRG during 20 days of drought. After 7 days of re-watering, drought-damaged leaves were rehydrated to the control level in KBG, but could not fully recover in PRG. KBG produced a greater number of new roots, while PRG had more rapid elongation of new roots after 16 days of re-watering. Superior drought tolerance in KBG was associated with osmotic adjustment, higher cell wall elasticity, and lower relative water content at zero turgor. Osmotic adjustment, cell wall elasticity, and cell membrane stability could play important roles in leaf desiccation tolerance and drought survival in perennial grass species. In addition, post-drought recovery of leaf hydration level and physiological activity could be associated with the accumulation of carbohydrates in leaves and rhizomes during drought stress and new root production after re-watering.

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