Heat tolerance of Portuguese old bread wheat varieties

Abstract

Wheat is a major staple crop, and its grain yield is affected by heat stress. Such environmental constraint frequently occurs in the main Portuguese wheat producing regions. The aim of this work was to evaluate the impact of high temperatures after anthesis on gas exchanges, chlorophyll a fluorescence, membrane integrity and yield in nine Portuguese old bread wheat varieties. Photosynthetic rate (Pn) reductions occurred in Gentil Rosso, Grécia and Nabã o and may result from inactivation of PSII activity, as indicated by decreases in photochemical efficiency under light (Fv'/Fm') and in quantum yield of electron transport ( e ). Results denoted an enhancement/maintenance of photosynthetic ability under heat, expressed by stable stomatal conductance (gs) and higher water use efficiency (WUE) in MEQ and Restauraçã o, increased Pn in MEB and Restauraçã o, and Pn stability in Ruivo. Reduced membrane damage (lower leakage) in Ruivo and MEQ suggested a higher protoplasmic tolerance to heat in these varieties. Control plants of MEQ also presented the highest lipid amount and the less unsaturated membrane lipids (low double bond index), and these traits were unaffected by heat. Ruivo denoted a stimulation of lipid biosynthesis which could have positive implications on thermal tolerance. Increased Pn and WUE, stable gs and abundant lipids in control plants (MEQ, T94, MEB, Restauraçã o) corresponded to kernel yield increases under heat. Physiological traits are expected to contribute to Portuguese wheat breeding programs towards high temperature tolerance.

Correlation between total lipids, linolenic acid and membrane injury under PEG-induced dehydration in leaves of Vigna genotypes differing in drought resistance

“…Under stress conditions, they undergo modifications which either enable them to acclimate to the new environment or lead to irreversible injury and cell death (Kuiper, 1985;Harwood, 1998).Qualitative and quantitative changes of membrane lipids have been involved in adaptation to many abiotic stresses, such as cold (Partelli et al, 2011;Scotti-Campos et al, 2014a), heat (Scotti-Campos et al, 2014b), aluminium toxicity (Huynh et al, 2012) and drought Matos et al, 2010;Scotti-Campos et al, 2013), among others.…”

Physiological responses to drought in four developed Triticum aestivum groups

“…Membrane injury has been widely used as an indicator of protoplasmic tolerance to abiotic stresses (Matos et al, 2002;Scotti-Campos et al, 2011). Raises in electrolyte leakage are usually related to irreversible membrane damage and the occurrence of membrane lipoperoxidative processes that lead to cell decompartmentation and tissues senescence (Lauriano et al, 2000;Scotti-Campos et al, 2014). Such losses of membrane integrity may also reflect damages occurring at chloroplast level, resulting in photosynthetic activity impairment (Matos et al, 2010;Scotti Campos et al, 2014).…”

“…Water shortage causes oxidative stress to the cells through reactive oxygen species formation, which result in damaged cellular structures (Blum and Ebercon, 1981), leading to cell decompartmentation and death. Membrane injury can be evaluated through increased electrolyte leakage (Campos and Pham Thi, 1997;Matos et al, 2002;Campos et al, 2003;Dias et al, 2010;Farooq et al, 2011;Scotti Campos et al, 2014). Plant reproductive development is extremely sensitive to abiotic stresses, so that any environmental perturbations may strongly affect final yield and quality (Dupont and Altenbach, 2003;Prasad et al, 2008).…”

Regulatory mechanism of enhancing polyphenol oxidase activity in leaf of Basella alba induced by high temperature stress

“…High temperature was found to be involved in causing higher PPO activity in leaf and the effects were more pronounced after 24 h of exposure although gradual increase in activity up to 72 h of periods was noted. It has been demonstrated that high temperature causes the higher oxidative stress inducing the synthesis of reactive oxygen species (ROS) (Mahajan and Tuteja, 2005) and increases tolerance to ROS in plants and with an increase in anti-oxidative enzymes (Scotti-Campos et al, 2014). Anti-oxidative enzymes can neutralize ROS and thereby prevents the cellular membranes and organelles from the damaging effects of ROS.…”