首页|Sucrose-associated SnRK1a1-mediated phosphorylation of Opaque2 modulates endosperm filling in maize
Sucrose-associated SnRK1a1-mediated phosphorylation of Opaque2 modulates endosperm filling in maize
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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 pro-motes 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.
State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China,Sichuan Agricultural University,Chengdu 611130,Sichuan,China
National Key Laboratory of Plant Molecular Genetics,CAS Center for Excellence in Molecular Plant Sciences,Shanghai Institute of Plant Physiology and Ecology,Chinese Academy of Sciences,Shanghai 200032,China
Institute of Molecular Breeding for Maize,Qilu Normal University,Jinan,China
National Natural Science Foundation of ChinaYoung Scientist ProjectOpen Project Program of the State Key Laboratory of Crop Gene Exploration and Utilization in Southwest ChinaTalent Initiation Program from Sichuan Agricultural University
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