Genotypic differences in thermotolerance are dependent upon prestress capacity for antioxidant protection of the photosynthetic apparatus inGossypium hirsutum

Abstract

Numerous studies have illustrated the need for antioxidant enzymes in acquired photosynthetic thermotolerance, but information on their possible role in promoting innate thermotolerance is lacking. We investigated the hypothesis that genotypic differences in source leaf photosynthetic thermostability would be dependent upon prestress capacity for antioxidant protection of the photosynthetic apparatus in Gossypium hirsutum. To test this hypothesis, thermosensitive (cv. ST4554) and reportedly thermotolerant (cv. VH260) G. hirsutum plants were exposed to control (30/20 degrees C) or high-day temperature (38/20 degrees C) conditions during flowering and source leaf gas exchange, chlorophyll content and maximum photochemical efficiency (F(v)/F(m)) were measured for each treatment. The relationship between source leaf thermostability and prestress antioxidant capacity was quantified by monitoring the actual quantum yield response of photosystem II (PSII) (Phi(PSII)) to a range of temperatures for both cultivars grown under the control temperature regime and measuring antioxidant enzyme activity for those same leaves. VH260 was more thermotolerant than ST4554 as evidenced by photosynthesis and F(v)/F(m) being significantly lower under high temperature for ST4554 but not VH260. Under identical growth conditions, VH260 had significantly higher optimal and threshold temperatures for Phi(PSII) and glutathione reductase (GR; EC 1.8.1.7) activity than ST4554, and innate threshold temperature was dependent upon endogenous GR and superoxide dismutase (SOD; EC 1.15.1.1) activity. We conclude that maintaining a sufficient antioxidant enzyme pool prior to heat stress is an innate mechanism for coping with rapid leaf temperature increases that commonly occur under field conditions.

Drought stress and carbon assimilation in a warming climate: Reversible and irreversible impacts

“…The production and the detoxification of reactive oxygen species (ROS) are important processes in plants exposed to drought and/or heat (Mittler and Zilinskas, 1994;Munne-Bosch et al, 2001;Mittler, 2002;Apel and Hirt, 2004;Reddy et al, 2004;Locato et al, 2008Locato et al, , 2009Simova-Stoilova et al, 2009;Snider et al, 2010;Osorio et al, 2011;Xu et al, 2013). ROS production is increased under abiotic stresses (energy dissipation) and as a consequence cellular constituents including proteins and membrane lipids may be damaged (Mittler, 2002).…”

“…Therefore ROS detoxification by enzymes (Xiao et al, 2008 ;Bian and Jiang, 2009;Fan et al, 2012;Salazar-Parra et al, 2012 ;Demeter et al, 2014;Sekmen et al, 2014;Song et al, 2014) or low molecular-weight compounds (Mittler, 2002) is essential for the functionality of leaf cells under abiotic stress. The xanthophyll cycle represents a plastid-specific ROS detoxification mechanism (Gallé et al, 2007;Haldimann et al, 2008;de la Rosa-Manzano et al, 2015), while other ROS detoxifying systems (e. g. superoxide dismutases) are present in several subcellular compartments (Locato et al, 2009;Simova-Stoilova et al, 2009;Snider et al, 2010;Song et al, 2014). The accumulation and compartmentation of some metabolites (expecially of ROS scavengers and of compatible solutes such as proline, betain or glycinebetaine which are also important for osmoregulation) help to protect cells from damages caused by heat or drought and to maintain basic cellular functions (Hormaetxe et al, 2007;Wang et al, 2010;Albert et al, 2012;Hu et al, 2013;Wujeska et al, 2013: AbdElgawad et al, 2015Grant et al, 2015).…”

cyp11A1 Canola plants under short time heat stress conditions

“…It was shown that the innate threshold temperature was dependent upon endogenous SOD and glutathione reductase activity in Gossypium hirsutum plants [20]. Under identical growth conditions, thermotolerant G. hirsutum plants had significantly higher optimal and threshold temperatures for the actual quantum yield response of photosystem II and glutathione reductase activity than thermosensitive ones.…”

“…It was documented that results of the heat tolerance test (short-time growth under 42 º Ñ in growth chamber) positively correlated with improvement of high temperature resistance in field trial [3]. We analyzed such physiological and biochemical parameters which are usually used to characterize the properties of plants under stress as relative water content [14,15], electrolyte leakage [15,16], photosynthetic pigment content and ratios [15,[17][18][19], SOD activity [3,20,21].…”

Extreme climatic events: impacts of drought and high temperature on physiological processes in agronomically important plants

“…Antioxidant enzyme activities such as catalases, peroxidases and superoxide dismutases play important role in the detoxification of ROS (Selote et al, 2004;Pastore et al, 2007;Bian and Jiang, 2009). A study on cotton varieties differing in thermotolerance suggests that there is a potential to incorporate the knowledge regarding the role of antioxidant enzymes in stress response for breeding of tolerant varieties (Snider et al, 2010) by the enhancement of in vivo levels of antioxidant enzymes. The relevance of high constitutive activities of ROS-detoxifying enzymes and of their on-going increase during abiotic stress was reported by Turkan et al (2005) for bean plants.…”