Abstract:

Seed priming is an efficient method to improve plant tolerance and yield. However， it is still not clear whether the deposition of plant cuticular wax is altered by seed priming thus improving plant resistance to some kinds of stress. In this study conducted in 2020， seeds of sweet sorghum （Sorghum bicolor ‘Dochna’） were primed with 15% polyethylene glycol （PEG）， 150 mg·L^-1 salicylic acid （SA）， 20 mg·L^-1 abscisic acid （ABA）， 5 mg·L^-1 gibberellin （GA） or water （control）， and subsequently sorghum plants at four growth stages （seedling， jointing， heading and maturity） were analyzed for total wax content， leaf water loss rate and chlorophyll extraction rate. The seeds were harvested and reseeded in 2021， and the transgenerational effects of seed priming on cuticular wax were measured. It was found that， compared to the control， the contents of total wax at different growth stages were significantly influenced， with 57.6%， 50.8% and 80.3% increases observed at the seedling stage for PEG-， SA- and ABA-priming. The contents of alkanes were increased by 58.7%， 35.5% and 36.5% （P<0.05 in each case） at seedling， heading， and maturity stages for ABA-priming. Furthermore， the relative abundances of C₂₇， C₂₉， and C₃₃ alkanes， C₂₈-C₃₂ aldehydes， and C₂₈ alcohols， were also improved. Meanwhile， seed priming increased the leaf relative water content but reduced the water loss rate and chlorophyll extraction rate. We concluded that PEG-， SA- and ABA-priming all influenced the deposition of cuticular wax， contributing to an improvement in cuticular resistance. Importantly， the effects of seed priming on wax synthesis had transgenerational “memory”， indicating a potential new method for production of “resistant” seed lines.

Key words: sweet sorghum, cuticular wax, seed priming, relative water content, water loss rate, resistance