Exogenous nitric oxide improves sugarcane growth and photosynthesis under water deficit

Abstract

Nitric oxide (NO)-mediated redox signaling plays a role in alleviating the negative impact of water stress in sugarcane plants by improving root growth and photosynthesis. Drought is an environmental limitation affecting sugarcane growth and yield. The redox-active molecule nitric oxide (NO) is known to modulate plant responses to stressful conditions. NO may react with glutathione (GSH) to form S-nitrosoglutathione (GSNO), which is considered the main reservoir of NO in cells. Here, we investigate the role of NO in alleviating the effects of water deficit on growth and photosynthesis of sugarcane plants. Well-hydrated plants were compared to plants under drought and sprayed with mock (water) or GSNO at concentrations ranging from 10 to 1000 μM. Leaf GSNO sprayed plants showed significant improvement of relative water content and leaf and root dry matter under drought compared to mock-sprayed plants. Additionally, plants sprayed with GSNO (≥ 100 μM) showed higher leaf gas exchange and photochemical activity as compared to mock-sprayed plants under water deficit and after rehydration. Surprisingly, a raise in the total S-nitrosothiols content was observed in leaves sprayed with GSH or GSNO, suggesting a long-term role of NO-mediated responses to water deficit. Experiments with leaf discs fumigated with NO gas also suggested a role of NO in drought tolerance of sugarcane plants. Overall, our data indicate that the NO-mediated redox signaling plays a role in alleviating the negative effects of water stress in sugarcane plants by protecting the photosynthetic apparatus and improving shoot and root growth.

Enhanced nitric oxide synthesis through nitrate supply improves drought tolerance of sugarcane plants

“…Such increase in root growth was associated with higher NO content (Fig. 6b), as found by Silveira et al (2016). At maximum water deficit, high NO synthesis was found in the root meristematic zone of plants supplied with 100% NO 3 − (Suppl.…”

“…The root system is able to perceive low water availability and to produce chemical signals that regulate the water flow from roots to shoots. NO is one of those chemical signals that stimulates root expansion and development (Xu et al , 2017; Silveira et al , 2016). Given the effects of NO on root growth, it is reasonable to assume a potential influence of NO mediating auxin signaling in roots.…”

“…For example, NO supply conferred drought tolerance to wheat seedlings, reducing membrane damage (Garcia-Mata and Lamattina, 2001). Spraying S-nitrosogluthatione (GSNO) – a NO donor – on sugarcane plants resulted in higher photosynthesis under drought, promoting plant growth under stressful condition (Silveira et al , 2016).…”

Improving water use efficiency by changing hydraulic and stomatal characteristics in soybean exposed to drought: the involvement of nitric oxide

“…As a signaling molecule, NO participates in several plant processes, including growth, respiration and photosynthesis, in addition to playing an important role in the responses of plants to biotic and abiotic stresses (Sami et al ). During WD, NO has been shown to promote root growth (Silveira et al ), increase the concentration of enzymatic and nonenzymatic antioxidants (Silveira et al ) and stomatal closure (together with abscisic acid; Joudoi et al ). Indeed, pretreatment with NO donors usually prepares plants for future stresses either by stimulating the antioxidant machinery or by inducing the production of endogenous NO, which in turn induces a series of additional events even after removal or degradation of the original NO donor (Santisree et al ).…”

“…Although several studies have clearly demonstrated the involvement of NO in mitigating the damage caused by WD, many questions remain unanswered. Most studies relate increased drought tolerance with the ability of NO to increase antioxidant defenses and to reduce the stomatal aperture (Santisree et al , Silveira et al , , Sami et al ) without considering its possible effects on hydraulic properties of the plant or the structural characteristics involved in the gas exchange. Indeed, studies that address the involvement of NO in the determination of g s have neglected the fact that, in addition to the degree of stomatal opening, maximum stomatal conductance can be determined by the morphological characteristics of stomata, like the stomatal size and density (Galmés et al ).…”