Photosynthetic and antioxidant responses to drought during sugarcane ripening

Abstract

Water deficit is an important exogenous factor that enhances the influx of sucrose into sugarcane (Saccharum spp.) stem internodes during ripening, when photosynthetic ability in supplying sinks is essential. The aim of this study was to test the hypothesis that drought tolerance in sugarcane is associated with an effective antioxidant protection during the ripening phase, which might maintain a favorable redox balance in chloroplasts and protect photosynthesis under drought conditions. Two commercial sugarcane varieties, IACSP94-2094 (tolerant) and IACSP96-2042 (sensitive), with contrasting behavior under water deficit, were subjected to water withholding during the ripening stage. Our results revealed that the tolerant variety was less affected by water deficit, maintaining photosynthesis for a longer period and showing a faster recovery after rehydration as compared to the sensitive one. As consequence, the tolerant variety faced lesser excess of light energy at PSII. The maintenance of photosynthesis under water deficit and its fast recovery after rehydration resulted in the lower leaf H2O2 concentration and favorable redox status in the drought-tolerant genotype, which was associated with stimulation of superoxide dismutase during ripening. Our results also revealed that ferric superoxide dismutase isoforms were strongly enhanced under drought conditions, playing an important role in chloroplast redox homeostasis.Additional key words: chlorophyll fluorescence; leaf gas exchange; oxidative stress; water stress.

Short-Time of Rehydration is not Effective to Re-Establish Chlorophyll Fluorescence and Gas Exchange in Two Cowpea Cultivars Submitted to Water Deficit

“…In addition, ETR/PN increased due to the increase previously described to NPQ, suggesting that occurred lower electron transfer to CO2 fixation, with consequent use of these electrons to photorespiration and other metabolic processes . Similar behavior was reported to EXC in Saccharum spp plants (Sales et al, 2015) and Jatropha curcas (Silva et al, 2015). Rivas et al (2016) studying two cultivars of V. unguiculata, 'Pingo de Ouro 1-2' and Santo Inácio, found reductions for NPQ in 80% and 200%, respectively, after 10 days of irrigation suspension.…”

Sugarcane Water Stress Tolerance Mechanisms and Its Implications on Developing Biotechnology Solutions

“…In addition, a correlation between water stress tolerance and lower levels of lipid peroxidation was reported (Cia et al, 2012; Sales et al, 2015). According to Abbas et al (2014) lipid peroxidation may be a good parameter to identify water stress tolerant sugarcane varieties.…”

“…The superoxide dismutase (SOD) activity plays the first line of enzymatic ROS scavenging, catalyzing the conversion of ${\text{O}}_2^{-}$ into H 2 O 2 within the cell. In sugarcane, SOD activity is genotype-dependent and is also modulated by water stress (Hemaprabha et al, 2004; Jain et al, 2015; Sales et al, 2015; dos Santos et al, 2015; dos Santos and de Almeida Silva, 2015). Moreover, (Jangpromma et al, 2012) showed that sugarcane cultivars classified as drought-tolerant exhibit higher levels of SOD activity under water deficit conditions.…”

Transpiração Foliar E Condutância Estomática Da Cana-De-Açúcar Em Função Do Clima E Disponibilidade De Água

“…Jackson et al (2015) compararam a variação genética de cinco genótipos de cana-de-açúcar em relação à eficiência da transpiração foliar. Sales et al (2015) testaram a hipótese de que a tolerância à seca em cana-de-açúcar está associada a uma resposta metabólica (antioxidante) eficaz durante a fase de amadurecimento, o que permite manter alta as taxas de fotossíntese durante a seca. Simões et al (2015) avaliaram as variáveis fisiológicas (transpiração e condutância estomática) da cana-de-açúcar em função do sistema de irrigação.…”