Silicon Enhances Water Stress Tolerance by Improving Root Hydraulic Conductance in Solanum lycopersicum L.

Abstract

Silicon (Si) can improve drought tolerance in plants, but the mechanism is still not fully understood. Previous research has been concentrating on Si’s role in leaf water maintenance in Si accumulators, while little information is available on its role in water uptake and in less Si-accumulating plants. Here, we investigated the effects of Si on root water uptake and its role in decreasing oxidative damage in relation to root hydraulic conductance in tomato (Solanum lycopersicum ‘Zhongza No.9’) under water stress. Tomato seedlings were subjected to water stress induced by 10% (w/v) polyethylene glycol-6000 in the absence or presence of 2.5 mM added silicate. The results showed that Si addition ameliorated the inhibition in tomato growth and photosynthesis, and improved water status under water stress. The root hydraulic conductance of tomato plants was decreased under water stress, and it was significantly increased by added Si. There was no significant contribution of osmotic adjustment in Si-enhanced root water uptake under water stress. The transcriptions of plasma membrane aquaporin genes were not obviously changed by Si under water stress. Water stress increased the production of reactive oxygen species and induced oxidative damage, while added Si reversed these. In addition, Si addition increased the activities of superoxide dismutase and catalase and the levels of ascorbic acid and glutathione in the roots under stress. It is concluded that Si enhances the water stress tolerance via enhancing root hydraulic conductance and water uptake in tomato plants. Si-mediated decrease in membrane oxidative damage may have contributed to the enhanced root hydraulic conductance.

Foliar Applications of Biostimulants Promote Growth, Yield and Fruit Quality of Strawberry Plants Grown under Nutrient Limitation

“…As for the use of biostimulant to contrast abiotic stresses, Goñi et al [8] and Di Stasio et al [9] recently reported the use of seaweed extracts from Ascophyllum nodosum to enhance the tolerance of tomato plants to drought and salinity stress, respectively. This positive effect was observed also with other biostimulants, such as protein hydrolysate on lettuce [10], chitosan on white clover [11], and silicon on tomato [12]. Regarding the stress caused by nutrient deficiency, biostimulants can contribute to soil nutrient availability, uptake, and assimilation of nutrients to the plants [13].…”

Silicon Regulates Antioxidant Activities of Crop Plants under Abiotic-Induced Oxidative Stress: A Review

“…Ma et al (2016) also suggested that Si supplement wheat plant showed lower lipid peroxidation, glutathione and total flavonoid content whereas increased ascorbate content was observed. Similarly, Shi et al (2014, 2016) reported that Si supplementation in tomato plants under PEG induced drought stress caused tolerance via increased SOD and CAT activities as well as improved water uptake ability of roots (Table 1). Whilst, Gunes et al (2008) observed that Si decreased MDA and APX activities in sunflower during drought condition (Table 1).…”

Beneficial effects of silicon on photosynthesis of tomato seedlings under water stress

“…Therefore, tomato may be an ideal plant to study the exact physiological and biochemical mechanism for siliconmediated tolerance to drought stress. In our previous study, we observed that exogenous silicon could increase water stress tolerance by enhancing root hydraulic conductance and decreasing oxidative damage in tomato seedlings (Shi et al 2016), suggesting the involvement of silicon in physiological and biochemical processes. However, the mechanism for silicon-mediated water stress tolerance in tomato still needs to be explored.…”