Gibberellin(GA)plays a major role in controlling Brassica rapa stalk development.As an essential negative regulator of GA signal transduction,DELLA proteins may exert significant effects on stalk development.However,t...Gibberellin(GA)plays a major role in controlling Brassica rapa stalk development.As an essential negative regulator of GA signal transduction,DELLA proteins may exert significant effects on stalk development.However,the regulatory mechanisms underlying this regulation remain unclear.In this study,we report highly efficient and inheritable mutagenesis using the CRISPR/Cas9 gene editing system in BraPDS(phytoene desaturase)and BraRGL1(key DELLA protein)genes.We observed a loss-of-function mutation in BraRGL1 due to two amino acids in GRAS domain.The flower bud differentiation and bolting time of BraRGL1 mutants were significantly advanced.The expression of GA-regulatory protein(BraGASA6),flowering related genes(BraSOC1,BraLFY),expansion protein(BraEXPA11)and xyloglucan endotransferase(BraXTH3)genes was also significantly upregulated in these mutants.BraRGL1-overexpressing plants displayed the contrasting phenotypes.BraRGL1 mutants were more sensitive to GA signaling.BraRGL1 interacted with BraSOC1,and the interaction intensity decreased after GA3 treatment.In addition,BraRGL1 inhibited the transcription-activation ability of BraSOC1 for BraXTH3 and BraLFY genes,but the presence of GA3 enhanced the activation ability of BraSOC1,suggesting that the BraRGL1-BraSOC1 module regulates bolting and flowering of B.rapa through GA signal transduction.Thus,we hypothesized that BraRGL1 is degraded,and BraSOC1 is released in the presence of GA3,which promotes the expression of BraXTH3 and BraLFY,thereby inducing stalk development in B.rapa.Further,the BraRGL1-M mutant promoted the flower bud differentiation without affecting the stalk quality.Thus,BraRGL1 can serve as a valuable target for the molecular breeding of early maturing varieties.展开更多
With rising living standards,consumers’demand for color diversity and nutritional quality in tomato products has increased.Flavonoids are a key determinant of peel color and nutritional value in tomato fruit,where th...With rising living standards,consumers’demand for color diversity and nutritional quality in tomato products has increased.Flavonoids are a key determinant of peel color and nutritional value in tomato fruit,where their biosynthesis is controlled by various phytohormones,including brassinosteroids(BRs).However,the underlying mechanism by which BR regulates flavonoid biosynthesis remains unclear.Here,we show that exogenous BRs suppress flavonoid accumulation,whereas reduced endogenous BR levels in RNAi lines of SlCYP90B3,a rate-limiting BR biosynthetic gene,result in increased flavonoid content in the fruit peel.We further demonstrate that BRI1-EMS-suppressor1(SlBES1),a basic helix–loop–helix transcription factor essential for BR signaling,not only regulates fruit firmness but also represses flavonoid accumulation by directly binding to the promoters of the flavonoid biosynthetic genes SlCHS1,SlCHS2,and SlF3'H.Additionally,SlBES1 modulates a hierarchical transcriptional cascade by repressing the expression of SlMYB12,further suppressing flavonoid biosynthesis.Moreover,the homologous transcription factor brassinazole-resistant1(SlBZR1)enhances SlBES1-mediated repression of flavonoid accumulation.Specifically,SlBES1 predominantly inhibits flavonoid biosynthesis,whereas SlBZR1 primarily enhances carotenoid pathway activity.Notably,variation in SlBES1 is correlated with flavonoid content during tomato domestication.Collectively,these results highlight a novel role for SlBES1 as a negative regulator of flavonoid biosynthesis,offering potential strategies for flavonoid biofortification in tomato.展开更多
文摘Gibberellin(GA)plays a major role in controlling Brassica rapa stalk development.As an essential negative regulator of GA signal transduction,DELLA proteins may exert significant effects on stalk development.However,the regulatory mechanisms underlying this regulation remain unclear.In this study,we report highly efficient and inheritable mutagenesis using the CRISPR/Cas9 gene editing system in BraPDS(phytoene desaturase)and BraRGL1(key DELLA protein)genes.We observed a loss-of-function mutation in BraRGL1 due to two amino acids in GRAS domain.The flower bud differentiation and bolting time of BraRGL1 mutants were significantly advanced.The expression of GA-regulatory protein(BraGASA6),flowering related genes(BraSOC1,BraLFY),expansion protein(BraEXPA11)and xyloglucan endotransferase(BraXTH3)genes was also significantly upregulated in these mutants.BraRGL1-overexpressing plants displayed the contrasting phenotypes.BraRGL1 mutants were more sensitive to GA signaling.BraRGL1 interacted with BraSOC1,and the interaction intensity decreased after GA3 treatment.In addition,BraRGL1 inhibited the transcription-activation ability of BraSOC1 for BraXTH3 and BraLFY genes,but the presence of GA3 enhanced the activation ability of BraSOC1,suggesting that the BraRGL1-BraSOC1 module regulates bolting and flowering of B.rapa through GA signal transduction.Thus,we hypothesized that BraRGL1 is degraded,and BraSOC1 is released in the presence of GA3,which promotes the expression of BraXTH3 and BraLFY,thereby inducing stalk development in B.rapa.Further,the BraRGL1-M mutant promoted the flower bud differentiation without affecting the stalk quality.Thus,BraRGL1 can serve as a valuable target for the molecular breeding of early maturing varieties.
基金supported by the National Natural Science Foundation of China(Key Program,32430091 and 32302523)the China Postdoctoral Science Foundation(2023M733133)the Zhejiang Province JianBingLingYan+X Research and Development Plan(2024C04015).Acknowledgments。
文摘With rising living standards,consumers’demand for color diversity and nutritional quality in tomato products has increased.Flavonoids are a key determinant of peel color and nutritional value in tomato fruit,where their biosynthesis is controlled by various phytohormones,including brassinosteroids(BRs).However,the underlying mechanism by which BR regulates flavonoid biosynthesis remains unclear.Here,we show that exogenous BRs suppress flavonoid accumulation,whereas reduced endogenous BR levels in RNAi lines of SlCYP90B3,a rate-limiting BR biosynthetic gene,result in increased flavonoid content in the fruit peel.We further demonstrate that BRI1-EMS-suppressor1(SlBES1),a basic helix–loop–helix transcription factor essential for BR signaling,not only regulates fruit firmness but also represses flavonoid accumulation by directly binding to the promoters of the flavonoid biosynthetic genes SlCHS1,SlCHS2,and SlF3'H.Additionally,SlBES1 modulates a hierarchical transcriptional cascade by repressing the expression of SlMYB12,further suppressing flavonoid biosynthesis.Moreover,the homologous transcription factor brassinazole-resistant1(SlBZR1)enhances SlBES1-mediated repression of flavonoid accumulation.Specifically,SlBES1 predominantly inhibits flavonoid biosynthesis,whereas SlBZR1 primarily enhances carotenoid pathway activity.Notably,variation in SlBES1 is correlated with flavonoid content during tomato domestication.Collectively,these results highlight a novel role for SlBES1 as a negative regulator of flavonoid biosynthesis,offering potential strategies for flavonoid biofortification in tomato.
