Exogenous treatment with melatonin enhances waterlogging tolerance of kiwifruit plants

Waterlogging stress has an enormous negative impact on the kiwifruit yield and quality. The protective role of exogenous melatonin on water stress has been widely studied, especially in drought stress. However, the research on melatonin-induced waterlogging tolerance is scarce. Here, we found that treatment with exogenous melatonin could effectively alleviate the damage on kiwifruit plants in response to waterlogging treatment. This was accompanied by higher antioxidant activity and lower ROS accumulation in kiwifruit roots during stress period. The detection of changes in amino acid levels of kiwifruit roots during waterlogging stress showed a possible interaction between melatonin and amino acid metabolism, which promoted the tolerance of kiwifruit plants to waterlogging. The higher levels of GABA and Pro in the roots of melatonin-treated kiwifruit plants partly contributed to their improved waterlogging tolerance. In addition, some plant hormones were also involved in the melatonin-mediated waterlogging tolerance, such as the enhancement of ACC accumulation. This study discussed the melatonin-mediated water stress tolerance of plants from the perspective of amino acid metabolism for the first time

Enhanced Autophagic Activity Improved the Root Growth and Nitrogen Utilization Ability of Apple Plants under Nitrogen Starvation

Autophagy is a conserved degradation pathway for recycling damaged organelles and aberrant proteins, and its important roles in plant adaptation to nutrient starvation have been generally reported. Previous studies found that overexpression of autophagy-related (ATG) gene MdATG10 enhanced the autophagic activity in apple roots and promoted their salt tolerance. The MdATG10 expression was induced by nitrogen depletion condition in both leaves and roots of apple plants. This study aimed to investigate the differences in the growth and physiological status between wild type and MdATG10-overexpressing apple plants in response to nitrogen starvation. A hydroponic system containing different nitrogen levels was used. The study found that the reduction in growth and nitrogen concentrations in different tissues caused by nitrogen starvation was relieved by MdATG10 overexpression. Further studies demonstrated the increased root growth and the higher nitrogen absorption and assimilation ability of transgenic plants. These characteristics contributed to the increased uptake of limited nitrogen nutrients by transgenic plants, which also reduced the starvation damage to the chloroplasts. Therefore, the MdATG10-overexpressing apple plants could maintain higher photosynthetic ability and possess better growth under nitrogen starvation stress

Overexpression of MdATG18a in apple improves resistance to Diplocarpon mali infection by enhancing antioxidant activity and salicylic acid levels

Improving resistance to apple blotch disease Apple plants that express high levels of a gene involved in the destruction of damaged and redundant cell components demonstrate improved resistance to a serious fungal infection. Fengwang Ma and colleagues of China’s Northwest A&F University in Shaanxi examined the effect of overexpressing the gene MdATG18a on Diplocarpon mali fungal infection in apple plants. This gene was previously found to promote drought tolerance in apple plants and is known for its involvement in autophagy, an immune response to infection that removes damaged cell organelles. The researchers found that plants overexpressing MdATG18a were more resistant to developing Marssonina apple blotch disease compared to wild apple plants, most likely due to improvements in autophagy activity. The team concludes that strategies designed to induce autophagy could improve apple resistance to fungal infection

Exogenous γ-aminobutyric acid enhances heat tolerance of kiwifruit plants by protecting photosynthetic system and promoting heat shock proteins expression

Kiwifruit plants are highly susceptible to increased atmospheric temperature, and the extreme high temperature often causes the loss of production and quality of the fruit. The γ-aminobutyric acid (GABA) has been widely proved to play important roles in plants in response to abiotic stresses, showing an important potential for application in agricultural industry to overcome environmental challenges. However, application of GABA in kiwifruit plants to resist external stresses has not been reported yet. This study found that pre-irrigation of kiwifruit plants with 0.5 mM GABA was effective in alleviating the heat damage on them. GABA treatment led to better antioxidant capacity and reduced ROS production in kiwifruit plants under high temperature. Moreover, exogenous GABA protected the photosynthetic system of kiwifruit plants when exposed to high temperature. Particularly, we found that endogenous ABA, Glu, Pro metabolisms were participated in the GABA-mediated heat resistance of kiwifruit plants. Furthermore, GABA treatment induced higher expression of AdHsps in kiwifruit plants, being partly responsible for their better performance under heat stress. In summary, this research first demonstrated that exogenous GABA treatment plays a positive role in kiwifruit plants to response to extreme heat stress