The Arabidopsis SUMO E3 ligase gene AtSIZ1 plays important roles in plant response to abiotic stresses as loss of function in AtSIZ1 leads to increased sensitivity to drought, heat and salt stresses. Overexpression of the AtSIZ1 rice homolog, OsSIZ1, leads to increased heat and drought tolerance in bentgrass, suggesting that the function of the E3 ligase SIZ1 is highly conserved in plants and it plays a critical role in abiotic stress responses. To test the possibility that the SUMO E3 ligase could be used to engineer drought- and heat-tolerant crops, the rice gene OsSIZ1 was overexpressed in cotton. We report here that overexpression of OsSIZ1 in cotton results in higher net photosynthesis and better growth than wild-type cotton under drought and thermal stresses in growth chamber and greenhouse conditions. Additionally, this tolerance to abiotic stresses was correlated with higher fiber yield in both controlled-environment and field trials carried out under reduced irrigation and rainfed conditions. These results suggest that OsSIZ1 is a viable candidate gene to improve crop yields under water-limited and rainfed agricultural production systems.

The Arabidopsis gene AtNHX1 encodes a vacuolar membrane-bound sodium/proton (Na⁺/H⁺) antiporter that transports Na⁺ into the vacuole and exports H⁺ into the cytoplasm. The Arabidopsis gene SOS1 encodes a plasma membrane-bound Na⁺/H⁺ antiporter that exports Na⁺ to the extracellular space and imports H⁺ into the plant cell. Plants rely on these enzymes either to keep Na⁺ out of the cell or to sequester Na⁺ into vacuoles to avoid the toxic level of Na⁺ in the cytoplasm. Overexpression of AtNHX1 or SOS1 could improve salt tolerance in transgenic plants, but the improved salt tolerance is limited. NaCl at concentration >200 mM would kill AtNHX1-overexpressing or SOS1-overexpressing plants. Here it is shown that co-overexpressing AtNHX1 and SOS1 could further improve salt tolerance in transgenic Arabidopsis plants, making transgenic Arabidopsis able to tolerate up to 250 mM NaCl treatment. Furthermore, co-overexpression of AtNHX1 and SOS1 could significantly reduce yield loss caused by the combined stresses of heat and salt, confirming the hypothesis that stacked overexpression of two genes could substantially improve tolerance against multiple stresses. This research serves as a proof of concept for improving salt tolerance in other plants including crops.

Hydrogen peroxide (H2O2) functions as a signal molecule in plants under abiotic and biotic stress. In this study, the role of exogenous H2O2 in improving drought tolerance in two soybean cultivars (Glycine max L. Merrill) differing in their tolerance to drought was evaluated. Plants were grown in plastic pots with normal irrigation in a phytotron. Four weeks after radicle emergence, either 1 mM H2O2 or distilled water was sprayed as foliar onto the leaves of each plant, after drought stress was applied. Leaf samples were harvested on the 4th and 7th days of the drought. Antioxidant-related enzyme activity, such as the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), hydrogen peroxide (H2O2) and malondialdehyde (MDA) content was measured during the drought period. Drought stress decreased leaf water potential, relative water content and photosynthetic pigment content but enhanced li...

Bamboo is nutritionally significant across the world because the shoots are high in calories and nutritional fiber but low in cholesterol. However, recent research has shown that bamboo shoots also contain a substantial quantity of heavy metals, including arsenic (As). Therefore, we explored whether the co-application of iron oxide nanoparticles (IONPs) and selenium nanoparticles (Se-NPs) would attenuate As toxicity in bamboo plants (Pleioblastus pygmaeus). A greenhouse experiment was performed to investigate plant responses to arsenic toxicity. Bamboo plants exposed to four levels of As (0, 10, 20, and 40 mg L⁻¹) were foliar-sprayed with 60 mg L⁻¹ of Se-NPs and 60 mg L⁻¹ of IONPs alone and in combination. The data indicated that different As concentrations (10, 20, and 40 mg L⁻¹) caused membrane damage and reactive oxide species (ROS) production in bamboo cells, characterized by H₂O₂, O₂^•−, MDA, and EL increasing by up to 47%, 54%, 57%, and 65%, respectively, in comparison with a control. The co-application of 60 mg L⁻¹ of Se-NPs + IONP markedly improved the antioxidant enzyme activities (by 75% in SOD, 27% in POD, 52% in CAT, 37% in GR, and 38% in PAL), total flavonoid content (42%), phenolic content (36%), proline (44%), nitric oxide (59%), putrescine (Put) (85%), spermidine (Spd) (53%), relative water content (RWC) (36%), photosynthetic characteristics (27%) in net photosynthesis (Pn) (24% in the intercellular CO₂ concentration (Ci), 39% in stomatal conductance (Gs), and 31% in chlorophyll pigments), and ultimately biomass indices and growth. The co-application of Se-NPs + IONPs with 10 and 20 mg L⁻¹ of As raised the TI by 14% and 9% in the shoot and by 18% and 14% in the root, respectively. IONPs and Se-NPs reduced ROS, cell membrane lipoperoxidation, and electrolyte leakage, all contributing to the decrease in oxidative stress by limiting As uptake and translocation. In sum, Se-NPs and IONPs improved bamboo endurance, yet the most effective approach for increasing bamboo’s ability to recover from As toxicity was the concurrent use of 60 mg L⁻¹ of Se-NPs and 60 mg L⁻¹ of IONPs. Our IONP and Se-NP data from single and combined applications offer novel knowledge in improving the tolerance mechanism against As exposure in Pleioblastus pygmaeus.