Bing-Bing Duan’s research while affiliated with Northwest A & F University and other places

The objective of this study was to investigate the role of the ascorbate-glutathione (AsA-GSH) cycle and abscisic acid (ABA) in brassinosteroids (BRs)-induced water tolerance in grape seedlings. The grape seedlings were treated with half-strength Hoaglands nutrient solution, polyethylene glycol (PEG-6000) and PEG combination with 24-epibrassinolide (EBR). The results showed that water stress led to typical drought injury symptoms and significantly increased in the contents of hydrogen peroxide (H2O2), the production rate of superoxide radicals (O2⁻) and the decrease in the contents of ascorbic acid, reduced glutathione in grape seedlings. However, application of EBR alleviated the water stress injury symptoms, reduced the H2O2 content and O2⁻ production rate and enhanced the contents of antioxidants and the activities of antioxidases involved in the AsA–GSH cycle. Interestingly, the ABA content, the transcriptional activation of some key genes involved in ABA biosynthesis including VviNCED1, VviNCED2 and VviZEP and ABA signaling-key genes (VviSnRK2.6, VviPP2C4, VviABF1 and VviABF2) were further enhanced with EBR treatment under water stress. Taken together, we speculate that there is a more complex mechanism in the crosstalk of BR and ABA under drought stress in grape seedlings and ABA is involved in brassinosteroids-induced antioxidant defense.

Cabernet Sauvignon and Cabernet Gernischt (Vitis vinifera L.) berries were sampled at seven stages from pre-veraison to harvest. According to seed weight to berry weight (SB) of berries, the sampled berries were divided into two groups as Low-SB and High-SB grapes. The results showed 0074hat most of colored grapes were Low-SB grapes while under-ripe green berries belonged to High-SB group at mid-veraison. What's more, compared with that of High-SB, there were more accumulation of sugar and anthocyanin and faster decreased total phenols in Low-SB berries. These were indicated that grapes with Low-SB ripened quicker. Abscisic acid (ABA) and auxin (IAA) were two main hormones in regulating berry ripening. Higher ABA and lower IAA concentration were observed in Low-SB grapes during maturation. To further illustrate the relationship of seed content with berry ripening, Cabernet Gernischt clusters were sprayed with 50 mg/L IAA. The results of this study suggested that IAA treatment delayed sugar and anthocyanin accumulation and retarded berry ripening, but increased the synchronicity of maturity by depressing the difference in sugar and anthocyanin contents between Low-SB and High-SB grapes. The delayed grapes had lower ABA and higher IAA content by reducing the expression of VvBG1, VvNCED, VvYUC1 and enhancing the expression of VvGH3-1. When the same amount of the control and IAA treatment grapes were mixed together, there were more grapes of IAA treatment belonged to the High-SB category and more berries of the control were Low-SB, further suggesting that seed content negatively correlated with berry ripening.