Drought, a primary abiotic stress, seriously affects plant growth and productivity. Stomata play a vital role in regulating gas exchange and drought adaptation. However, limited knowledge exists of the molecular mechanisms underlying stomatal movement in trees. Here, PeCHYR1, a ubiquitin E3 ligase, was isolated from Populus euphratica, a model of stress adaptation in forest trees. PeCHYR1 was preferentially expressed in young leaves and was significantly induced by ABA (abscisic acid) and dehydration treatments. To study the potential biological functions of PeCHYR1, transgenic poplar 84K (Populus alba × Populus glandulosa) plants overexpressing PeCHYR1 were generated. PeCHYR1 overexpression significantly enhanced H2 O2 production and reduced stomatal aperture. Transgenic lines exhibited increased sensitivity to exogenous ABA and greater drought tolerance than that of WT (wild-type) controls. Moreover, up-regulation of PeCHYR1 promoted stomatal closure and decreased transpiration, resulting in strongly elevated WUE (water use efficiency). When exposed to drought stress, transgenic poplar maintained higher photosynthetic activity and biomass accumulation. Taken together, these results suggest that PeCHYR1 plays a crucial role in enhancing drought tolerance via ABA-induced stomatal closure caused by hydrogen peroxide (H2 O2 ) production in transgenic poplar plants.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/pbi.12893

PeCHYR1, a ubiquitin E3 ligase from Populus euphratica, enhances drought tolerance via ABA-induced stomatal closure by ROS production in Populus.

In plants, water deficiency can result from a deficit of water from the soil, an obstacle to the uptake of water or the excess water loss; in these cases, the similar consequence is the limitation of plant growth and crop yield. Silicon (Si) has been widely reported to alleviate the plant water status and water balance under variant stress conditions in both monocot and dicot plants, especially under drought and salt stresses. However, the underlying mechanism is unclear. In addition to the regulation of leaf transpiration, recently, Si application was found to be involved in the adjustment of root hydraulic conductance by up-regulating aquaporin gene expression and concentrating K in the xylem sap. Therefore, this review discusses the potential effects of Si on both leaf transpiration and root water absorption, especially focusing on how Si modulates the root hydraulic conductance. A growing number of studies support the conclusion that Si application improves plant water status by increasing root water uptake, rather than by decreasing their water loss under conditions of water deficiency. The enhancement of plant water uptake by Si is achievable through the activation of osmotic adjustment, improving aquaporin activity and increasing the root/shoot ratio. The underlying mechanisms of the Si on improving plant water uptake under water deficiency conditions are discussed.

/pdf/how-does-silicon-mediate-plant-water-uptake-and-loss-under-g6g45cuub5.pdf

How Does Silicon Mediate Plant Water Uptake and Loss Under Water Deficiency

Determination of phytochemicals and antioxidant activity of methanol extracts obtained from the fruit and leaves of Tunisian Lycium intricatum Boiss.

Appraisal of emerging crop management opportunities in fruit trees, grapevines and berry crops facilitated by the application of biostimulants

The role of some elicitors on the management of Roumy Ahmar grapevines downy mildew disease and it's related to inducing growth and yield characters

The influences of silicon (Si) on parameters, such as plant growth, pigment contents, photosynthesis, chlorophyll fluorescence, soluble sugar and starch concentration, and some cell ultra-structures, were investigated in grapevines under salt stress. Compared with the control, the treatment with 100 mM NaCl dramatically inhibited the growth of grapevines and greatly decreased the content of pigments. Silicon treatment in the absence of salt had negative effects in most observed parameters. However, the addition of Si under salt stress improved all growth parameters and increased the pigments and photosynthetic rates compared with the NaCl treatment. Furthermore, investigation of chlorophyll fluorescence, soluble sugars, starch concentration and cell ultra-structure indicated that photosynthesis in the NaCl treatment decreased. The supplement of silicon mitigated the inhibited photosynthesis caused by NaCl, and increased the maximum yield and potential photochemical efficiency of the photochemical reactions in photosystem II. On the other hand, the addition of exogenous Si and NaCl also increased the concentration of soluble sugars and starch, and influenced ultra-structural changes. It is possible that silicon might play an important role in protecting photosynthetic machinery from damage and improving the salt-tolerance of the grape by increasing the concentration of soluble sugars and starch.

The influence of silicon application on growth and photosynthesis response of salt stressed grapevines (Vitis vinifera L.)

The extraction technique of flavonoids from the tender leaves and fruits of medlar (Lycium chinense Miller) were investigated, and ability to scavenge 1,1-diphenyl 2-picrylhydrazyl (DPPH) radicals of both was compared. Through single-factor and the L9 (34) orthogonaldesign, the optimal extraction parameters were determined. The results showed that the flavonoids content was significantly higher in the leaves than in the fruits. There were four important factors influencing the yields of flavonoids, including ethanol concentration, extraction time, solid-liquid ratio and extraction temperature. As for leaves, the optimum extraction parameters were 80% ethanol content, solid-liquid ratio 1:50, extract times 2times per 40 min, and 60°C. While for fruits, the optimum parameters were 80% ethanol content, 1:50 solid-liquid ratio, 2 per 30 min and 60°C. Under the optimum condition, the yield of flavonoids from leaves and fruits are 47.371 and 9.593 mg.g-1, respectively. Theflavonoids in leaves and fruits have good capability to scavenge the DPPH radicals, and the scavenging capability is obviously related to the concentrations.

	 

	Key words: Ultrasonic-assisted extraction, Lycium chinense Miller, flavonoids, 1,1-diphenyl 2-picrylhydrazyl (DPPH), free radical scavenging activity.

Ultrasonic-assisted extraction flavonoids and ability to scavenge 1,1-diphenyl 2-picrylhydrazyl (DPPH) radicals from medlar (a Miller) leaves and fruits

Wen-huai Kang

Papers

The influence of silicon application on growth and photosynthesis response of salt stressed grapevines (Vitis vinifera L.)

Ultrasonic-assisted extraction flavonoids and ability to scavenge 1,1-diphenyl 2-picrylhydrazyl (DPPH) radicals from medlar (a Miller) leaves and fruits