High temperature-induced hypocotyl elongation is a typical thermomorphogenesis trait that may significantly affect early seedling growth and subsequent crop yield.The ambient temperature and endogenous auxin are two c...High temperature-induced hypocotyl elongation is a typical thermomorphogenesis trait that may significantly affect early seedling growth and subsequent crop yield.The ambient temperature and endogenous auxin are two critical factors that regulate hypocotyl growth.However,the mechanism of temperature and auxin integration in horticultural plants remains poorly understood.In this study,the roles of the basic helix-loop-helix transcription factor CsPIF4 in regulating auxin biosynthesis genes and the auxin content in the hypocotyl of cucumber(Cucumis sativus L.)seedlings under high temperature were investigated.qRT-PCR and in situ hybridization analysis revealed that expression of CsPIF4 was enhanced in the epidermis and vascular bundles in the hypocotyl of cucumber seedlings in response to high temperature.qRT-PCR and HPLC analysis showed that CsPIF4 positively regulated transcription of the auxin biosynthesis gene CsYUC8 and the auxin content in the hypocotyl under high temperature(35℃).The CRISPR/Cas9-mediated knockout of CsPIF4 resulted in a shorter hypocotyl compared with that of the wild type,together with decreased expression of CsYUC8 and lower auxin content in response to high temperature.Furthermore,biochemical assays showed that CsPIF4 could bind directly to the G-box motif of the CsYUC8 promoter and thereby activate CsYUC8 expression.These findings provide insight into the molecular mechanism of high temperature-mediated hypocotyl elongation in cucumber.展开更多
Shoot branching is an important crop agronomic trait that directly affects plant architecture and crop productivity.Although phytochrome B(phy B),BRANCHED1(BRC1),and abscisic acid(ABA) mediate axillary bud outgrowth,i...Shoot branching is an important crop agronomic trait that directly affects plant architecture and crop productivity.Although phytochrome B(phy B),BRANCHED1(BRC1),and abscisic acid(ABA) mediate axillary bud outgrowth,it is unknown if there is any integrating factor among them in the Plantae.We report that mutation of Csphy B or inactivation of Csphy B by shade inhibits lateral bud outgrowth in cucumber.Cucumber PHYTOCHROME INTERACTING FACTOR 4(Cs PIF4) interacts with Csphy B and directly binds to the promoter of CsBRC1 to activate CsBRC1 expression.CsBRC1 also directly promotes the expression of ABA biosynthesis gene 9-CIS-EPOXICAROTENOID DIOXIGENASE 3(CsNCED3).Functional disruption of Cs PIF4 decreased expression of CsBRC1 and CsNCED3,reduced ABA accumulation,and increased bud outgrowth in cucumber.Csnced3 mutants had reduced ABA levels and increased lateral bud outgrowth.These results suggest that a regulatory network involving Csphy B-Cs PIF4-CsBRC1 exists that integrates light signaling and ABA biosynthesis to modulate bud outgrowth.This provides a strategy to manipulate branch numbers in crop breeding to realize ideal branching characteristics to maximize yield.展开更多
基金the China Postdoctoral Science Foundation(Grant No.2021M703530)the National Natural Science Foundation of China(Grant No.31972398).
文摘High temperature-induced hypocotyl elongation is a typical thermomorphogenesis trait that may significantly affect early seedling growth and subsequent crop yield.The ambient temperature and endogenous auxin are two critical factors that regulate hypocotyl growth.However,the mechanism of temperature and auxin integration in horticultural plants remains poorly understood.In this study,the roles of the basic helix-loop-helix transcription factor CsPIF4 in regulating auxin biosynthesis genes and the auxin content in the hypocotyl of cucumber(Cucumis sativus L.)seedlings under high temperature were investigated.qRT-PCR and in situ hybridization analysis revealed that expression of CsPIF4 was enhanced in the epidermis and vascular bundles in the hypocotyl of cucumber seedlings in response to high temperature.qRT-PCR and HPLC analysis showed that CsPIF4 positively regulated transcription of the auxin biosynthesis gene CsYUC8 and the auxin content in the hypocotyl under high temperature(35℃).The CRISPR/Cas9-mediated knockout of CsPIF4 resulted in a shorter hypocotyl compared with that of the wild type,together with decreased expression of CsYUC8 and lower auxin content in response to high temperature.Furthermore,biochemical assays showed that CsPIF4 could bind directly to the G-box motif of the CsYUC8 promoter and thereby activate CsYUC8 expression.These findings provide insight into the molecular mechanism of high temperature-mediated hypocotyl elongation in cucumber.
基金supported by grants from the National Natural Science Foundation of China(32372699, 32025033, and 32102387)Key R&D Program of Shandong Province,China (2024LZGCQY006)S&T Program of Hebei (22326308D)。
文摘Shoot branching is an important crop agronomic trait that directly affects plant architecture and crop productivity.Although phytochrome B(phy B),BRANCHED1(BRC1),and abscisic acid(ABA) mediate axillary bud outgrowth,it is unknown if there is any integrating factor among them in the Plantae.We report that mutation of Csphy B or inactivation of Csphy B by shade inhibits lateral bud outgrowth in cucumber.Cucumber PHYTOCHROME INTERACTING FACTOR 4(Cs PIF4) interacts with Csphy B and directly binds to the promoter of CsBRC1 to activate CsBRC1 expression.CsBRC1 also directly promotes the expression of ABA biosynthesis gene 9-CIS-EPOXICAROTENOID DIOXIGENASE 3(CsNCED3).Functional disruption of Cs PIF4 decreased expression of CsBRC1 and CsNCED3,reduced ABA accumulation,and increased bud outgrowth in cucumber.Csnced3 mutants had reduced ABA levels and increased lateral bud outgrowth.These results suggest that a regulatory network involving Csphy B-Cs PIF4-CsBRC1 exists that integrates light signaling and ABA biosynthesis to modulate bud outgrowth.This provides a strategy to manipulate branch numbers in crop breeding to realize ideal branching characteristics to maximize yield.
