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 sucr...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.展开更多
Although the genetic basis for endosperm development in maize(Zea mays)has been well studied,the mechanism for coordinating grain filling with increasing kernel size remains elusive.Here,we report that increased kerne...Although the genetic basis for endosperm development in maize(Zea mays)has been well studied,the mechanism for coordinating grain filling with increasing kernel size remains elusive.Here,we report that increased kernel size was selected during modern breeding and identify a novel DELLA-like transcriptional regulator,ZmGRAS11,which positively regulates kernel size and kernel weight in maize.We find that Opaque2,a core transcription factor for zein protein and starch accumulation,transactivates the expression of Zm GRAS11.Our data suggest that the Opaque2-Zm GRAS11 module mediates synergistic endosperm enlargement with grain filling.展开更多
Quality protein maize(QPM)(Zea mays L.) varieties contain enhanced levels of tryptophan and lysine, exhibiting improved nutritive value for humans and livestock. However, breeding QPM varieties remains challenging due...Quality protein maize(QPM)(Zea mays L.) varieties contain enhanced levels of tryptophan and lysine, exhibiting improved nutritive value for humans and livestock. However, breeding QPM varieties remains challenging due to the complex process of rebalancing storage protein. This study conducted transcriptome and proteome analyses to investigate the process of storage proteins rebalancing in opaque2(o2) and QPM. We found a weak correlation between the transcriptome and proteome, suggesting a significant modulating effect of post-transcriptional events on non-zein protein abundances in Mo17o2 and QPM. These results highlight the advantages of proteomics. Compared with Mo17, 672 differentially expressed proteins(DEPs) were identified both in Mo17o2 and QPM, and several of them were associated with storage protein, starch, and amino acid synthesis. We identified 178 non-zeins as DEPs in Mo17o2 and QPM kernels. The up-regulated non-zein DEPs were enriched in lysine, tryptophan, and methionine, which affected the protein quality. Co-expression network analysis identified regulators of storage protein synthesis in QPM, including O2,PBF1, and several transcription factors. Our results revealed how storage protein rebalancing occurs and identified nonzein DEPs that may facilitate superior-quality QPM breeding.展开更多
基金supported by the National Natural Science Foundation of China(31925030 to Y.W.)Young Scientist Project(2023YFD1200008 to T.Y.)+1 种基金Open Project Program(SKL-ZY202211)of the State Key Laboratory of Crop Gene Exploration and Utilization in Southwest ChinaTalent Initiation Program from Sichuan Agricultural University.
文摘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.
基金supported by the National Natural Science Foundation of China to X.J.Z.(grant number 31771707)National Special Program for GMO Development of China to R.M.C.(2016ZX08003-002)the National Key Basic Research Program of China(2014CB138205)。
文摘Although the genetic basis for endosperm development in maize(Zea mays)has been well studied,the mechanism for coordinating grain filling with increasing kernel size remains elusive.Here,we report that increased kernel size was selected during modern breeding and identify a novel DELLA-like transcriptional regulator,ZmGRAS11,which positively regulates kernel size and kernel weight in maize.We find that Opaque2,a core transcription factor for zein protein and starch accumulation,transactivates the expression of Zm GRAS11.Our data suggest that the Opaque2-Zm GRAS11 module mediates synergistic endosperm enlargement with grain filling.
基金supported by the National Natural Science Foundation of China (31971951 and 31771796)。
文摘Quality protein maize(QPM)(Zea mays L.) varieties contain enhanced levels of tryptophan and lysine, exhibiting improved nutritive value for humans and livestock. However, breeding QPM varieties remains challenging due to the complex process of rebalancing storage protein. This study conducted transcriptome and proteome analyses to investigate the process of storage proteins rebalancing in opaque2(o2) and QPM. We found a weak correlation between the transcriptome and proteome, suggesting a significant modulating effect of post-transcriptional events on non-zein protein abundances in Mo17o2 and QPM. These results highlight the advantages of proteomics. Compared with Mo17, 672 differentially expressed proteins(DEPs) were identified both in Mo17o2 and QPM, and several of them were associated with storage protein, starch, and amino acid synthesis. We identified 178 non-zeins as DEPs in Mo17o2 and QPM kernels. The up-regulated non-zein DEPs were enriched in lysine, tryptophan, and methionine, which affected the protein quality. Co-expression network analysis identified regulators of storage protein synthesis in QPM, including O2,PBF1, and several transcription factors. Our results revealed how storage protein rebalancing occurs and identified nonzein DEPs that may facilitate superior-quality QPM breeding.
