Drought stress has become a limiting factor for viticulture with climate change. The influence of arbuscular mycorrhizal fungi (AMF) on grapevine Vitis vinifera L. cv. Ecolly’s leaf water content, chlorophyll concentration, photosynthesis activity, and chlorophyll fluorescence under drought stress was studied in the greenhouse. The experiment was designed as a randomized complete block with four treatments: AMF colonization, well-watered; non-AMF colonization, well-watered; AMF colonization with drought stress; and non-AMF colonization with drought stress. The grapevines inoculated with mycorrhiza had a higher water content in the leaves and higher chlorophyll concentration under drought stress than those without mycorrhiza inoculation. AMF colonization increased the dry biomass of shoots and roots, photosynthetic rate, stomatal conductance, and transpiration rate and decreased intercellular CO2 concentration. Mycorrhizal grapevines had higher non-photochemistry efficiency, higher photochemistry efficiency, and higher actual quantum yield than non-mycorrhizal grapevines. The results show that AMF alleviated the negative effects of drought stress on grapevines. The alleviation improved leaf water status, chlorophyll concentration, and photosynthetic capacity. Altogether, the results of our study indicate that AMF inoculation has the potential to protect grapevines under drought stress.
Downy mildew is a major threat to viticulture, leading to severe yield loss. The use of traditional copper-based fungicides is effective, but has adverse effects on the environment and human health, making it urgent to develop an environmentally friendly disease management program. Multi-functional kaolin particle film (KPF) is promising as an effective and safer treatment strategy, since this material lacks chemically active ingredients. In this study, ability of Kaolin particle film (KPF) pretreatment to protect grapevine leaves from Plasmopara viticola was tested and the mode of action of KPF was analyzed. KPF application reduced the disease severity and the development of intercellular hyphae. Additionally, there was reduced accumulation of H2O2 and malondialdehyde (MDA) with pretreatment. The observation of ultrastructure on the leaf surface showed KPF deposition and stomatal obstruction, indicating that KPF protected plants against disease by preventing the adhesion of pathogens to the leaf surface and blocking invasion through the stomata. KPF pretreatment also activated host defense responses, as evidenced by increased activities of anti-oxidative enzymes [superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)] and defense-related enzymes [phenylalanine ammonia-lyase (PAL), chitinases, and β-1,3-glucanases], increased phytohormone signals [abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA)] and the up-regulation of defense genes related to plant defense. Overall, these results demonstrate that KPF treatment counters grapevine downy mildew by protecting leaves and enhancing plant defense responses.
Agricultural bioinoculants containing arbuscular mycorrhizal fungi represent a potential opportunity to reduce the dependence of grapevines (Vitis) on agrochemicals. This field study assessed the ability of four commercial bioinoculants to colonize grapevine roots and their effects on petiole nutrient concentration, berry composition, and root morphology of ‘Pinot noir’ (Vitis vinifera) grafted onto rootstock ‘Couderc 3309’ (Vitis riparia × Vitis rupestris) and ‘Riesling’ (V. vinifera) grafted onto ‘Couderc 3309’ and Selection Oppenheim four (Vitis berlandieri × V. riparia). Three bioinoculants increased root mycorrhizal colonization; however, regardless of the treatment, mycorrhizal fungal structures were enhanced. Grapevine petiole nutrient concentration was improved by bioinoculants. Root diameter, root length density, and specific root length increased with greater mycorrhizal root colonization. Using bioinoculants to reduce chemical fertilizers may be a good strategy to improve grapevine productivity and health in cool climates; however, the impact of mycorrhizal bioinoculants in the vineyard may differ among scion–rootstocks, edaphoclimatic conditions, and vineyard soil microbiomes.
Bunch compactness is an important trait that affects the sanitary status and quality of wine grapes. Many studies have demonstrated that canopy managements, such as leaf removal, shoot trimming, and postponed first shoot topping, can effectively reduce compactness. However, few studies have determined the effects of canopy management measures on bunch compactness. Shoot wrapping has been previously shown to elongate the rachis length and reduce bunch compactness. Here, we tested whether the presence of laterals affects cluster growth in Vitis vinifera L. ‘Riesling’ through a field experiment with four treatments over two consecutive seasons: shoot wrapping with laterals, shoot wrapping without laterals, hedging with laterals, and hedging without laterals. Laterals were removed weekly. Lateral removal had little effect on cluster compactness; the effect was shown temporarily and not consistent the growing seasons. The effect of laterals on cluster compactness and rachis length slightly varied with years. The short-term and variable effect of laterals may be explained by the fact that they experienced little competition with clusters.
Background and Aims. Drought harms the growth and productivity of grapevines; it thus poses a major threat to the development of viticulture in the background of ongoing climate change. Arbuscular mycorrhizal fungi (AMF) can be used to enhance the resistance/tolerance of plants to environmental stress. The effects of AMF on the osmotic regulation, antioxidant substances, and expression of drought-responsive genes in the grapevine Vitis vinifera L. cv. Ecolly were studied. Methods and Results. The experiment was conducted in a greenhouse in a completely randomized block design with four treatments: AMF colonization, well-watered; non-AMF colonization, well-watered; AMF colonization with drought stress; and non-AMF colonization with drought stress. The concentration of sucrose and proline in the leaves was higher in mycorrhizal grapevine than in nonmycorrhizal grapevine under drought stress. The concentration of malonaldehyde, hydrogen peroxide, superoxide anion, and glutathione and the activity of superoxide dismutase and peroxidase activity in leaves were higher in mycorrhizal grapevine than in nonmycorrhizal grapevine under drought conditions. AMF inoculation affected the expression of drought-responsive genes. Mycorrhization upregulated the expression of VvNCED, VvP5CS, VvSIP, VvPIP1;2, and VvTIP2;1 genes under drought stress. Conclusions. AMF could reduce the harm caused by drought stress by regulating osmosis, antioxidant activities, and the expression of key drought-responsive genes and aquaporin genes. Significance of the Study. This work provides insights into the physiological and biochemical activities influenced by AMF on grapevine under drought stress.
Damage to pancreatic β-cells is closely associated with diabetes. However, the mechanism underlying injury to pancreatic β-cells remains unclear, although hypoxia is considered as one of the leading causes. Appoptosin is a mitochondrial protein that promotes neuronal apoptosis. Studies conducted on appoptosin thus far have primarily focused on Alzheimer's disease, and have demonstrated that the expression of appoptosin is significantly increased in ischemic-reperfused rat brains, which indicates its close association with hypoxia. However, the role of appoptosin in pancreatic β-cells, which are sensitive to hypoxia, remains unknown. Therefore, the current study aimed to investigate the function of appoptosin in pancreatic β-cells in a hypoxic environment. Cobalt chloride (CoCl2) was used to mimic the hypoxic status of the cells. The results of a terminal deoxynucleotidyl transferase dUTP nick-end labeling assay demonstrated that CoCl2 promoted apoptosis in MIN6 mouse insulinoma cells, and western blotting and reverse transcription-quantitative polymerase chain reaction results demonstrated that the activation of appoptosin was induced, promoting mitochondrial damage and caspase 3 activation. Silencing of appoptosin using short hairpin RNA significantly reduced CoCl2-induced apoptosis in MIN6 cells. In conclusion, CoCl2 increased the expression of appoptosin, which aggravated mitochondrial damage in MIN6 cells. Therefore, inhibiting the expression of appoptosin may benefit pancreatic β-cells survival during islet transplantation.
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