Tomato production is influenced by shoot branching,which is controlled by different hormones.Here we produced tomato plants overexpressing the cytokinin-deactivating gene CYTOKININ OXYDASE 2(CKX2).CKX2-overexpressing(...Tomato production is influenced by shoot branching,which is controlled by different hormones.Here we produced tomato plants overexpressing the cytokinin-deactivating gene CYTOKININ OXYDASE 2(CKX2).CKX2-overexpressing(CKX2-OE)plants showed an excessive growth of axillary shoots,the opposite phenotype expected for plants with reduced cytokinin content,as evidenced by LC-MS analysis and ARR5-GUS staining.The TCP transcription factor SlBRC1b was downregulated in the axillary buds of CKX2-OE and its excessive branching was dependent on a functional version of the GRAS-family gene LATERAL SUPPRESSOR(LS).Grafting experiments indicated that increased branching in CKX2-OE plants is unlikely to be mediated by root-derived signals.Crossing CKX2-OE plants with transgenic antisense plants for the strigolactone biosynthesis gene CAROTENOID CLEAVAGE DIOXYGENASE(CCD7-AS)produced an additive phenotype,indicating independent effects of cytokinin and strigolactones on increased branching.On the other hand,CKX2-OE plants showed reduced polar auxin transport and their bud outgrowth was reduced when combined with auxin mutants.Accordingly,CKX2-OE basal buds did not respond to auxin applied in the decapitated apex.Our results suggest that tomato shoot branching depends on a fine-tuning of different hormonal balances and that perturbations in the auxin status could compensate for the reduced cytokinin levels in CKX2-OE plants.展开更多
基金L.E.P.received a PhD scholarship(2004/15268-0)and a postdoctoral fellowship(2014/16553-1)from Sao Paulo State Research Foundation(FAPE SP).L.E.P.PA.F.received fellowships from Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)(306518/2018-0 and 302710/2017-5)+3 种基金This work was partially supported by a FAPESP grant(No.2015/50220-2)AZ was partly funded by a grant(RED-00053-16)fromFoundation for Research Assistance of the Minas Gerais State(FAPEMIG,Brazil)a CAPES/Alexander von Humboldt Foundation Experienced Researcher Fellowship(88881.472837/2019-01).
文摘Tomato production is influenced by shoot branching,which is controlled by different hormones.Here we produced tomato plants overexpressing the cytokinin-deactivating gene CYTOKININ OXYDASE 2(CKX2).CKX2-overexpressing(CKX2-OE)plants showed an excessive growth of axillary shoots,the opposite phenotype expected for plants with reduced cytokinin content,as evidenced by LC-MS analysis and ARR5-GUS staining.The TCP transcription factor SlBRC1b was downregulated in the axillary buds of CKX2-OE and its excessive branching was dependent on a functional version of the GRAS-family gene LATERAL SUPPRESSOR(LS).Grafting experiments indicated that increased branching in CKX2-OE plants is unlikely to be mediated by root-derived signals.Crossing CKX2-OE plants with transgenic antisense plants for the strigolactone biosynthesis gene CAROTENOID CLEAVAGE DIOXYGENASE(CCD7-AS)produced an additive phenotype,indicating independent effects of cytokinin and strigolactones on increased branching.On the other hand,CKX2-OE plants showed reduced polar auxin transport and their bud outgrowth was reduced when combined with auxin mutants.Accordingly,CKX2-OE basal buds did not respond to auxin applied in the decapitated apex.Our results suggest that tomato shoot branching depends on a fine-tuning of different hormonal balances and that perturbations in the auxin status could compensate for the reduced cytokinin levels in CKX2-OE plants.
