Gibberellins(GAs)play a crucial role in growth and development of the tomato fruit.Previously published studies focusing on the effect of GAs on tomato fruits used chemical treatments,constitutive overexpression or si...Gibberellins(GAs)play a crucial role in growth and development of the tomato fruit.Previously published studies focusing on the effect of GAs on tomato fruits used chemical treatments,constitutive overexpression or silencing of GA biosynthetic and catabolic genes globally throughout the plant.Fruit-specific overexpression of GA catabolic enzyme genes GA2-oxidases(GA2oxs),however,may provide an alternative method to study the role of endogenous GAs on the fruit development.In this study,we have identified 11 SlGA2ox proteins in tomato that are classified into three subgroups.Motif analysis and multiple sequence alignments have demonstrated that all SlGA2oxs,except SlGA2ox10,have similar motif compositions and high-sequence conservation.Quantitative reverse transcription-PCR analysis has showed that SlGA2oxs exhibit differential expression patterns in tomato fruits at different developmental stages.When the fruit-specific promoter TFM7 was used to control the expression of SlGA2ox1,we observed no changes in growth and development of vegetative organs.However,fruit weight,seed number and germination rate were significantly affected.We also treated tomato fruits with GA biosynthesis inhibitor and observed phenotypes similar to those of the transgenic fruits.Furthermore,we have demonstrated that expression of cell expansion and GA responsive genes were downregulated in transgenic tomato fruits,supporting that overexpression of the SlGA2ox1 leads to reduction in endogenous GAs.This study provides additional evidence that endogenous GAs and the SlGA2ox1 gene play an important role in controlling on fruit weight,seed development and germination in tomato plant.展开更多
Isopentenyltransferase(IPT)genes,including those encoding ATP/ADP-IPTs and tRNA-IPTs,control the rate-limiting steps of the biosynthesis of N6-(Δ2-isopentenyl)adenine(iP)-type and trans-zeatin(tZ)-type cytokinins and...Isopentenyltransferase(IPT)genes,including those encoding ATP/ADP-IPTs and tRNA-IPTs,control the rate-limiting steps of the biosynthesis of N6-(Δ2-isopentenyl)adenine(iP)-type and trans-zeatin(tZ)-type cytokinins and cis-zeatin(cZ)-type cytokinins,respectively.However,the evolution and roles of these IPTs in angiosperms are not well understood.Here,we report comprehensive analyses of the origins,evolution,expression patterns,and possible roles of ATP/ADP-IPTs and tRNA-IPTs in angiosperms.We found that Class I and II tRNA-IPTs likely coexisted in the last common ancestor of eukaryotes,while ATP/ADP-IPTs likely originated from a Class II tRNA-IPT before the divergence of angiosperms.tRNA-IPTs are conservatively retained as 2–3 copies,but ATP/ADP-IPTs exhibit considerable expansion and diversification.Additionally,tRNA-IPTs are constitutively expressed throughout the plant,whereas the expression of ATP/ADP-IPTs is tissue-specific and rapidly downregulated by abiotic stresses.Furthermore,previous studies and our present study indicate that ATP/ADP-IPTs and their products,iPs/tZs,may regulate responses to environmental stresses and organ development in angiosperms.We therefore hypothesize that tRNA-IPTs and the associated cZs play a housekeeping role,whereas ATP/ADP-IPTs and the associated iP/tZ-type cytokinins play regulatory roles in organ development and stress responses in angiosperms,which echoes the conclusions and hypothesis presented in the accompanying study by Wang,X.et al Evolution and roles of cytokinin genes in angiosperms 2:Do ancient CKXs play housekeeping roles while non-ancient CKXs play regulatory roles?Hortic Res https://doi.org/10.1038/s41438-020-0246-z.展开更多
Cytokinin oxidase/dehydrogenase(CKX)is a key enzyme responsible for the degradation of endogenous cytokinins.However,the origins and roles of CKX genes in angiosperm evolution remain unclear.Based on comprehensive bio...Cytokinin oxidase/dehydrogenase(CKX)is a key enzyme responsible for the degradation of endogenous cytokinins.However,the origins and roles of CKX genes in angiosperm evolution remain unclear.Based on comprehensive bioinformatic and transgenic plant analyses,we demonstrate that the CKXs of land plants most likely originated from an ancient chlamydial endosymbiont during primary endosymbiosis.We refer to the CKXs retaining evolutionarily ancient characteristics as“ancient CKXs”and those that have expanded and functionally diverged in angiosperms as“non-ancient CKXs”.We show that the expression of some non-ancient CKXs is rapidly inducible within 15 min upon the dehydration of Arabidopsis,while the ancient CKX(AtCKX7)is not drought responsive.Tobacco plants overexpressing a non-ancient CKX display improved oxidative and drought tolerance and root growth.Previous mutant studies have shown that non-ancient CKXs regulate organ development,particularly that of flowers.Furthermore,ancient CKXs preferentially degrade cis-zeatin(cZ)-type cytokinins,while non-ancient CKXs preferentially target N6-(Δ2-isopentenyl)adenines(iPs)and trans-zeatins(tZs).Based on the results of this work,an accompanying study(Wang et al.https://doi.org/10.1038/s41438-019-0211-x)and previous studies,we hypothesize that non-ancient CKXs and their preferred substrates of iP/tZ-type cytokinins regulate angiosperm organ development and environmental stress responses,while ancient CKXs and their preferred substrates of cZs play a housekeeping role,which echoes the conclusions and hypothesis described in the accompanying report(Wang,X.et al.Evolution and roles of cytokinin genes in angiosperms 1:Doancient IPTs play housekeeping while non-ancient IPTs play regulatory roles?Hortic Res 7,(2020).https://doi.org/10.1038/s41438-019-0211-x).展开更多
基金The research was supported by the following:General Financial Grant from the China Postdoctoral Science Foundation(2015M581812)Special Financial Grant from the China Postdoctoral Science Foundation(2016T90471)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Gibberellins(GAs)play a crucial role in growth and development of the tomato fruit.Previously published studies focusing on the effect of GAs on tomato fruits used chemical treatments,constitutive overexpression or silencing of GA biosynthetic and catabolic genes globally throughout the plant.Fruit-specific overexpression of GA catabolic enzyme genes GA2-oxidases(GA2oxs),however,may provide an alternative method to study the role of endogenous GAs on the fruit development.In this study,we have identified 11 SlGA2ox proteins in tomato that are classified into three subgroups.Motif analysis and multiple sequence alignments have demonstrated that all SlGA2oxs,except SlGA2ox10,have similar motif compositions and high-sequence conservation.Quantitative reverse transcription-PCR analysis has showed that SlGA2oxs exhibit differential expression patterns in tomato fruits at different developmental stages.When the fruit-specific promoter TFM7 was used to control the expression of SlGA2ox1,we observed no changes in growth and development of vegetative organs.However,fruit weight,seed number and germination rate were significantly affected.We also treated tomato fruits with GA biosynthesis inhibitor and observed phenotypes similar to those of the transgenic fruits.Furthermore,we have demonstrated that expression of cell expansion and GA responsive genes were downregulated in transgenic tomato fruits,supporting that overexpression of the SlGA2ox1 leads to reduction in endogenous GAs.This study provides additional evidence that endogenous GAs and the SlGA2ox1 gene play an important role in controlling on fruit weight,seed development and germination in tomato plant.
基金Yi Li holds a no pay visiting professor position at Nanjing Agricultural University.
文摘Isopentenyltransferase(IPT)genes,including those encoding ATP/ADP-IPTs and tRNA-IPTs,control the rate-limiting steps of the biosynthesis of N6-(Δ2-isopentenyl)adenine(iP)-type and trans-zeatin(tZ)-type cytokinins and cis-zeatin(cZ)-type cytokinins,respectively.However,the evolution and roles of these IPTs in angiosperms are not well understood.Here,we report comprehensive analyses of the origins,evolution,expression patterns,and possible roles of ATP/ADP-IPTs and tRNA-IPTs in angiosperms.We found that Class I and II tRNA-IPTs likely coexisted in the last common ancestor of eukaryotes,while ATP/ADP-IPTs likely originated from a Class II tRNA-IPT before the divergence of angiosperms.tRNA-IPTs are conservatively retained as 2–3 copies,but ATP/ADP-IPTs exhibit considerable expansion and diversification.Additionally,tRNA-IPTs are constitutively expressed throughout the plant,whereas the expression of ATP/ADP-IPTs is tissue-specific and rapidly downregulated by abiotic stresses.Furthermore,previous studies and our present study indicate that ATP/ADP-IPTs and their products,iPs/tZs,may regulate responses to environmental stresses and organ development in angiosperms.We therefore hypothesize that tRNA-IPTs and the associated cZs play a housekeeping role,whereas ATP/ADP-IPTs and the associated iP/tZ-type cytokinins play regulatory roles in organ development and stress responses in angiosperms,which echoes the conclusions and hypothesis presented in the accompanying study by Wang,X.et al Evolution and roles of cytokinin genes in angiosperms 2:Do ancient CKXs play housekeeping roles while non-ancient CKXs play regulatory roles?Hortic Res https://doi.org/10.1038/s41438-020-0246-z.
基金supported by the National Natural Science Foundation of China[grant number 31471860 to J.D.and number 31401842 to H.W.]the Open Project of the State Key Laboratory of Crop Genetics and Germplasm Enhancement[grant number ZW2014008 to H.W.].
文摘Cytokinin oxidase/dehydrogenase(CKX)is a key enzyme responsible for the degradation of endogenous cytokinins.However,the origins and roles of CKX genes in angiosperm evolution remain unclear.Based on comprehensive bioinformatic and transgenic plant analyses,we demonstrate that the CKXs of land plants most likely originated from an ancient chlamydial endosymbiont during primary endosymbiosis.We refer to the CKXs retaining evolutionarily ancient characteristics as“ancient CKXs”and those that have expanded and functionally diverged in angiosperms as“non-ancient CKXs”.We show that the expression of some non-ancient CKXs is rapidly inducible within 15 min upon the dehydration of Arabidopsis,while the ancient CKX(AtCKX7)is not drought responsive.Tobacco plants overexpressing a non-ancient CKX display improved oxidative and drought tolerance and root growth.Previous mutant studies have shown that non-ancient CKXs regulate organ development,particularly that of flowers.Furthermore,ancient CKXs preferentially degrade cis-zeatin(cZ)-type cytokinins,while non-ancient CKXs preferentially target N6-(Δ2-isopentenyl)adenines(iPs)and trans-zeatins(tZs).Based on the results of this work,an accompanying study(Wang et al.https://doi.org/10.1038/s41438-019-0211-x)and previous studies,we hypothesize that non-ancient CKXs and their preferred substrates of iP/tZ-type cytokinins regulate angiosperm organ development and environmental stress responses,while ancient CKXs and their preferred substrates of cZs play a housekeeping role,which echoes the conclusions and hypothesis described in the accompanying report(Wang,X.et al.Evolution and roles of cytokinin genes in angiosperms 1:Doancient IPTs play housekeeping while non-ancient IPTs play regulatory roles?Hortic Res 7,(2020).https://doi.org/10.1038/s41438-019-0211-x).
