Induction of Heat Stress Tolerance in Barley Seedlings by Pre-Sowing Seed Treatment with Glycinebetaine

Abstract

Heat stress adversely affects plant growth and development, while glycinebetaine (GB) plays a protective role under stressful conditions. The objective of this study was to assess the optimum level of GB for use as a presowing seed treatment and the subsequent effect on the heat tolerance of barley (Hordeum vulgare L. cv. Haider-93) seedlings. Among a range of GB levels, the 20 mM concentration emerged as the most effective in enhancing seed germination, shoot fresh and dry weight and shoot water content under heat stress, and this level was selected for further studies. Time course changes revealed that the seedlings developing from 20 mM GB treated seeds had greater shoot dry weight, net photosynthetic rate (P N ), leaf water potential (w w ) and reduced relative membrane permeability (RMP), compared to no-GB treated plants under heat stress. Correlations between dry weight and high P N (r = 0.881), low w w (r = À0.938) and RMP (r = À0.860) of shoots suggested the involvement of GB in heat stress tolerance. Leakage of Ca 2+ and NO 3 À was the greatest followed by K + and PO 4 3À under no-GB seed treatment, and GB application under heat stress appreciably reduced the leakage of all these ions, particularly Ca 2+ , K + and NO 3 À . In conclusion GB absorbed by seeds, after translocation to the seedlings, enhanced their capacity to maintain greater water content, and higher seedling vigor by virtue of increased P N , reduced RMP and leakage of important ions under heat stress. These results have implications for final field stand under the conditions where the ambient temperature is supra-optimal for barley growth.

H2O2 pretreated rice seedlings specifically reduces arsenate not arsenite: difference in nutrient uptake and antioxidant defense response in a contrasting pair of rice cultivars

“…Among various strategies, pre-soaking and priming of seeds with stress alleviating compounds has been proposed as an easy, low cost, low risk and effective approach to overcome the abiotic stresses (Wahid and Shabbir 2005). It is well established that most of the biotic and abiotic stress response results into generation of H 2 O 2, hence, priming rice seedlings with H 2 O 2 would induce a well developed antioxidative defence mechanism prior to As exposure, and treatment with H 2 O 2 + SA could also have additive effect, as the mode of SA in plants is through generation of H 2 O 2 .…”

Comparative Ability of Some Growth Regulators for Inducing Thermotolerance in Cotton Under Different Thermal Regimes

“…Reproductive stages of early sown cotton come during the hottest months that can cause serious reduction in yield (Rahman et al, 2007;Khan et al, 2014). Growth regulators are organic or inorganic substances activating plant defensive system under abiotic stresses (Wahid and Shabbir, 2005). Hydrogen peroxide (H2O2) and salicylic acid (SA) are useful substances having role towards the release of stress (Gechev et al, 2006).…”

Tolerância cruzada induzida por choque térmico na germinação de semente de feijão

“…Alguns estudos atestam que é possível atenuar o estresse hídrico através da indução das proteínas de choque térmico ou através de utilização de substâncias osmoprotetoras, como indução de dissacarídeos osmoprotetores, poliaminas ou indução de enzimas extratoras de radicais livres (Maity et al, 2000;McCue et al, 2000;Matovina & Blake, 2001;Sung Shim et al, 2003;Panda e Khan, 2004;Wahid & Shabbir, 2005;Neid & Biesboer et al, 2005;Kumari et al, 2006). Nesse sentido, a atenuação do estresse hídrico foi obtida em sementes submetidas às soluções acrescidas de poliaminas, devido ao significativo aumento na porcentagem de germinação (Fonseca e Perez, 2003).…”