Effects of Different Selenium Fertilizer Types on Selenium Content and Quality of "Lingfeng" Grapes

[Objectives]This study was conducted to choose a selenium-rich foliar fertilizer suitable for the selenium-rich fruit and vegetable industry in Guangxi.[Methods]With "Lingfeng" wine grapes as test materials,such four kinds of selenium fertilizers as "Jufu Selenium"(JF),"Taishan Weed Fertilizer"(TS),"Zhongnong No.6"(ZN) and "Kangxibao"(KX) were used as exogenous selenium for the experiment of selenium-enriched grapes.[Results]The selenium contents in the grape fruit applied with the selenium fertilizers increased by 1.2-16.8 times compared with the control (CK),and JF and ZN had a better selenium-enriching effect and produced the fruit having the selenium contents reaching 75.85 and 45.79 μg/kg,respectively.Spraying selenium fertilizers can improve some quality indexes of grapes in that spraying JF on the leaves can significantly increase the total sugar content of the grapes while reducing the total acid content and spraying ZN significantly improved the vitamin C content of the fruit.With the delay of harvesting,the selenium content,total sugar content and total acid content of the "Lingfeng" grape fruit decreased,while the grapes sprayed with ZN showed the total sugar content increased slightly and the total acid decreased greatly.[Conclusions]It is suggested that if you plan to harvest at the right time,you can use "Jufu Selenium" as the exogenous fertilizer for selenium-enriched grapes;and if you want to postpone harvesting,you can use "Zhongnong No.6" as the selenium fertilizer.

Sucrose-associated SnRK1a1-mediated phosphorylation of Opaque2 modulates endosperm filling in maize

During maize endosperm filling,sucrose not only serves as a source of carbon skeletons for storage-reserve synthesis but also acts as a stimulus to promote this process.However,the molecular mechanisms underlying sucrose and endosperm filling are poorly understood.In this study,we found that sucrose promotes the expression of endosperm-filling hub gene Opaque2(O2),coordinating with storage-reserve accumulation.We showed that the protein kinase SnRK1a1 can attenuate O2-mediated transactivation,but sucrose can release this suppression.Biochemical assays revealed that SnRK1a1 phosphorylates O2 at serine 41(S41),negatively affecting its protein stability and transactivation ability.We observed that mutation of SnRK1a1 results in larger seeds with increased kernel weight and storage reserves,while overexpression of SnRK1a1 causes the opposite effect.Overexpression of the native O2(O2-OE),phospho-dead(O2-SA),and phospho-mimetic(O2-SD)variants all increased 100-kernel weight.Although O2-SA seeds exhibit smaller kernel size,they have higher accumulation of starch and proteins,resulting in larger vitreous endosperm and increased test weight.O2-SD seeds display larger kernel size but unchanged levels of storage reserves and test weight.O2-OE seeds show elevated kernel dimensions and nutrient storage,like a mixture of O2-SA and O2-SD seeds.Collectively,our study discovers a novel regulatory mechanism of maize endosperm filling.Identification of S41 as a SnRK1-mediated phosphorylation site in O2 offers a potential engineering target for enhancing storage-reserve accumulation and yield in maize.