[Objective] Genetic Engineering technology was used to regulate the expression of PttGA20-oxidase gene thus restrained plant height growth and internode elongation for cultivating dwarfed plant.[Method] Based on the R...[Objective] Genetic Engineering technology was used to regulate the expression of PttGA20-oxidase gene thus restrained plant height growth and internode elongation for cultivating dwarfed plant.[Method] Based on the RNAi principle,the gene specific sequences of PttGA20-oxidase in the antisense and sense orientations interrupted by a gene sequence from GUS were cloned into a binary vector pBI121.The selection marker gene npt Ⅱ was replaced with bar gene to RNAi plasmid.[Result] After undergone different endonuclease restrictions,the constructed constraint vector released different segments whose sizes were similar to that of target segment,which demonstrated that the RNAi plasmid of PttGA20-oxidase gene was successfully constructed.[Conclusion] The experiment provided a new way for culturing dwarfed plant.展开更多
Gibberellin 3-oxidase catalyzes the conversion of inactive gibberellin(GA) species into GAs with biological activity and it is subjected to strict developmental controls in the life cycle of a plant. In this study, 33...Gibberellin 3-oxidase catalyzes the conversion of inactive gibberellin(GA) species into GAs with biological activity and it is subjected to strict developmental controls in the life cycle of a plant. In this study, 33 gene sequences, encoding the gibberellin 3-oxidase(GA3ox) from Dasypyrum villosum and its dwarf mutant, were obtained. Each contained a 1 107 bp coding sequence(CDS) that encoded a putative protein containing 369 amino acids. The GA3ox protein showed 77% to 97% homology and shared the major conserved structural domains of GA3ox proteins with rice, sorghum bicolor, oat, barley, and wheat. Sequence alignment showed that there were 20 single nucleotide polymorphisms(SNPs) and 22 Insertion/deletions(In Dels) among these sequences, which could be divided into 2 haplotypes, haplotypes Ⅰ and Ⅱ. Haplotype Ⅰ was found in the wild type and was1 495 bp in length, and haplotype Ⅱ was found in the dwarf mutant and was 1 485 bp in length. The Q-PCR results showed that GA3ox was expressed in the leaves, roots, internodes, and stem nodes, and that there was a significant difference in the transcript level of the GA3ox between the wild type and dwarf mutant. The transcript levels of GA3ox in the leaves at the seedling stage, stem elongation stage and the heading stage, in the root and stem nodes at the stem elongation stage and in the internodes at the heading stage of the wild type, were significantly higher than those in the dwarf mutant. However, GA3ox expression in the rest of the wild type tissues at the 3 stages was slightly higher than or not different from the dwarf mutant.The results suggested that the wild type and mutant allele sequences of GA3ox in D. villosum showed 2 amino acid changes in exons and variations in the lengths of introns or the SNPs in introns, which most probably impaired the function of the enzyme,affected the GA3ox expression level, and eventually gave rise to dwarfing.展开更多
Drought stress is a devastating natural disaster driven by the continuing intensification of global warming,which seriously threatens the productivity and quality of several horticultural crops,including pear.Gibberel...Drought stress is a devastating natural disaster driven by the continuing intensification of global warming,which seriously threatens the productivity and quality of several horticultural crops,including pear.Gibberellins(GAs)play crucial roles in plant growth,development,and responses to drought stress.Previous studies have shown significant reductions of GA levels in plants under drought stress;however,our understanding of the intrinsic regulation mechanisms of GA-mediated drought stress in pear remains very limited.Here,we show that drought stress can impair the accumulation of bioactive GAs(BGAs),and subsequently identified PbrGA2ox1 as a chloroplast-localized GA deactivation gene.This gene was significantly induced by drought stress and abscisic acid(ABA)treatment,but was suppressed by GA_(3)treatment.PbrGA2ox1-overexpressing transgenic tobacco plants(Nicotiana benthamiana)exhibited enhanced tolerance to dehydration and drought stresses,whereas knock-down of PbrGA2ox1 in pear(Pyrus betulaefolia)by virus-induced gene silencing led to elevated drought sensitivity.Transgenic plants were hypersensitive to ABA,and had a lower BGAs content,enhanced reactive oxygen species(ROS)scavenging ability,and augmented ABA accumulation and signaling under drought stress compared to wild-type plants.However,the opposite effects were observed with PbrGA2ox1 silencing in pear.Moreover,exogenous GA_(3)treatment aggravated the ROS toxic effect and restrained ABA synthesis and signaling,resulting in the compromised drought tolerance of pear.In summary,our results shed light on the mechanism by which BGAs are eliminated in pear leaves under drought stress,providing further insights into the mechanism regulating the effects of GA on the drought tolerance of plants.展开更多
Gibberellin （GA） 2-oxidase plays a key role in the GA catabolic pathway through 2β-hydroxylation.In the present study,we isolated a CaMV 35S-enhancer activation tagged mutant,H032.This mutant exhibited a dominant d...Gibberellin （GA） 2-oxidase plays a key role in the GA catabolic pathway through 2β-hydroxylation.In the present study,we isolated a CaMV 35S-enhancer activation tagged mutant,H032.This mutant exhibited a dominant dwarf and GA-deficient phenotype,with a final stature that was less than half of its wild-type counterpart.The endogenous bioactive GAs are markedly decreased in the H032 mutant,and application of bioactive GAs （GA3 or GA4） can reverse the dwarf phenotype.The integrated T-DNA was detected 12.8 kb upstream of the OsGA2ox6 in the H032 genome by TAIL-PCR.An increased level of OsGA2ox6 mRNA was detected at a high level in the H032 mutant,which might be due to the enhancer role of the CaMV 35S promoter.RNAi and ectopic expression analysis of OsGA2ox6 indicated that the dwarf trait and the decreased levels of bioactive GAs in the H032 mutant were a result of the up-regulation of the OsGA2ox6 gene.BLASTP analysis revealed that OsGA2ox6 belongs to the class III of GA 2-oxidases,which is a novel type of GA2ox that uses C20-GAs （GA12 and/or GA53） as the substrates.Interestingly,we found that a GA biosynthesis inhibitor,paclobutrazol,positively regulated the OsGA2ox6 gene.Unlike the over-expression of OsGA2ox1,which led to a high rate of seed abortion,the H032 mutant retained normal flowering and seed production.These results indicate that OsGA2ox6 mainly affects plant stature,and the dominant dwarf trait of the H032 mutant can be used as an efficient dwarf resource in rice breeding.展开更多
Optimal plant height is crucial in modern agriculture, influencing lodging resistance and facilitating mechanized crop production. Upland cotton (Gossypium hirsutum) is the most important fiber crop globally;however, ...Optimal plant height is crucial in modern agriculture, influencing lodging resistance and facilitating mechanized crop production. Upland cotton (Gossypium hirsutum) is the most important fiber crop globally;however, the genetic basis underlying plant height remains largely unexplored. In this study, we conducted a genome-wide association study to identify a major locus controlling plant height (PH1) in upland cotton. This locus encodes gibberellin 2-oxidase 1A (GhPH1) and features a 1133-bp structural variation (PAVPH1) located approximately 16 kb upstream. The presence or absence of PAVPH1 influences the expression of GhPH1, thereby affecting plant height. Further analysis revealed that a gibberellin-regulating transcription factor (GhGARF) recognizes and binds to a specific CATTTG motif in both the GhPH1 promoter and PAVPH1. This interaction downregulates GhPH1, indicating that PAVPH1 functions as a distant upstream silencer. Intriguingly, we found that DWARF53 (D53), a key repressor of the strigolactone (SL) signaling pathway, directly interacts with GhGARF to inhibit its binding to targets. Moreover, we identified a previously unrecognized gibberellin-SL crosstalk mechanism mediated by the GhD53-GhGARF-GhPH1/PAVPH1 module, which is crucial for regulating plant height in upland cotton. These findings shed light on the genetic basis and gene interaction network underlying plant height, providing valuable insights for the development of semi-dwarf cotton varieties through precise modulation of GhPH1 expression.展开更多
Alfalfa(Medicago sativa L.)is a nutritious forage crop with wide ecological adaptability.The molecular breeding of alfalfa is restricted by its heterozygous tetraploid genome and the difficult genetic manipulation pro...Alfalfa(Medicago sativa L.)is a nutritious forage crop with wide ecological adaptability.The molecular breeding of alfalfa is restricted by its heterozygous tetraploid genome and the difficult genetic manipulation process.Under time and resource constraints,we applied a more convenient approach.We investigated two MtGA3ox genes,MtGA3ox1 and MtGA3ox2,of Medicago truncatula,a diploid legume model species,finding that MtGA3ox1 plays a major role in GA-regulated plant architecture.Mutation of neither gene affected nitrogenase activity.These results suggest that MtGA3ox1 can be used in semidwarf and prostrate alfalfa breeding.Based on the M.truncatula MtGA3ox1 sequence,MsGA3ox1 was cloned from alfalfa,and two knockout targets were designed.An efficient CRISPR/Cas9-based genome editing protocol was used to generate msga3ox1 mutants in alfalfa.We obtained three lines that carried mutations in all four alleles in the T0 generation.Fifteen clonal plants were vegetatively propagated from each transgenic line using shoot cuttings.The plant height and internode length of msga3ox1 null mutants were significantly decreased.The number of total lateral branches,leaf/stem ratio and crude protein content of aerial plant parts of msga3ox1 mutants were significantly increased.Thus,we obtained semi-dwarf and prostrate alfalfa by gene editing.展开更多
Senescence is the process of programmed degradation. The G2 line of pea exhibits apical senescence-delaying phenotype under short-day （SD） conditions, but the mechanism regulating the apical senescence is still larg...Senescence is the process of programmed degradation. The G2 line of pea exhibits apical senescence-delaying phenotype under short-day （SD） conditions, but the mechanism regulating the apical senescence is still largely unknown. Gibberellin （GA） was proved to be able to delay this apical senescence phenotype in G2 pea grown under long-day （LD） conditions. Here we show that the initiation of cell death signals in the terminal floral meristem was involved in the regulation of apical senescence in pea plants. SD signals prevented the formation of the cell death region in the apical mersitem. Moreover, GA3 treatment could effectively inhibit the occurrence of cell death-mediated apical senescence in LD-grown apical buds. Therefore, our data suggest that the prevention of apical senescence in SD-grown G2 pea through GA3 treatment may be largely responsible for the regulation of occurrence of the DNA fragmentation in apical meristem.展开更多
Tomato is an ideal model species for fleshy fruit development research. Sl YABBY2 b regulates the ovary locule number, which is increased by gibberellins, in tomato. However, the relationship between Sl YABBY2 b and e...Tomato is an ideal model species for fleshy fruit development research. Sl YABBY2 b regulates the ovary locule number, which is increased by gibberellins, in tomato. However, the relationship between Sl YABBY2 b and endogenous gibberellin is poorly understood. In this study, Sl YABBY2 b-overexpressing and RNA interference(RNAi) transgenic tomato plants were used to elucidate the mechanism by which Sl YABBY2 b regulates the ovary locule number and endogenous gibberellin content in tomato. Sl YABBY2 b-overexpressing plants showed fewer locules and lower gibberellin content than the control plants. Contrasting results were found in the RNAi lines. Therefore, the Sl YABBY2 b gene negatively regulates tomato ovary locule number and endogenous gibberellin content. Furthermore, the expression of Sl YABBY2 b gene was remarkably higher than that of the wild type in the apical shoots of gibberellindeficient mutants. This showed that the gibberellins can inhibit the expression of Sl YABBY2 b gene negative regulation. Further study revealed that Sl YABBY2 b suppressed the expression of Sl GA20 ox1 and Sl GA3 ox2, but increased that of Sl GA2 ox1 and Sl GA2 ox5 in the apical shoots of Sl YABBY2 b-overexpressing plants, thereby reducing gibberellin content. Contrasting results were found in the RNAi lines. Our results showed that the Sl YABBY2 b gene was located on gibberellin signal transduction pathways, fed back regulation of the synthesis of gibberellin, and felt exogenous gibberellin signal to further regulate the formation of tomato locule.展开更多
The phytohormones gibberellic acid （GA） and abscisic acid （ABA） antagonistically control seed germina- tion. High levels of GA favor seed germination, whereas high levels of ABA hinder this process. The direct rel...The phytohormones gibberellic acid （GA） and abscisic acid （ABA） antagonistically control seed germina- tion. High levels of GA favor seed germination, whereas high levels of ABA hinder this process. The direct relationship between GA biosynthesis and seed germina- tion ability need further investigation. Here, we identified the ABA-insensitive gain-of-function mutant germination insensitive to ABA mutant 2 （gim2） by screening a population of XVE T-DNA-tagged mutant lines. Based on two loss-of-function gim2-ko mutant lines, the disruption of GIM2 function caused a delay in seed germination. By contrast, upregulation of GIM2 accelerated seed germina- tion, as observed in transgenic lines overexpressing GIM2 （OE）. We detected a reduction in endogenous bioactive GA levels and an increase in endogenous ABA levels in the gim2-ko mutants compared to wild type. Conversely, the OE lines had increased endogenous bioactive GA levels and decreased endogenous ABA levels. The expression levels of a set of GA- and]or ABA-related genes were altered in both the gim2-ko mutants and the OE lines. We confirmed that GIM2 has dioxygenase activity using an in vitro enzyme assay, observing that GIM2 can oxidize GA^2. Hence, our characterization of GIM2 demonstrates that it plays a role in seed germination by affecting the GA metabolic pathway in Arabidopsis.展开更多
文摘[Objective] Genetic Engineering technology was used to regulate the expression of PttGA20-oxidase gene thus restrained plant height growth and internode elongation for cultivating dwarfed plant.[Method] Based on the RNAi principle,the gene specific sequences of PttGA20-oxidase in the antisense and sense orientations interrupted by a gene sequence from GUS were cloned into a binary vector pBI121.The selection marker gene npt Ⅱ was replaced with bar gene to RNAi plasmid.[Result] After undergone different endonuclease restrictions,the constructed constraint vector released different segments whose sizes were similar to that of target segment,which demonstrated that the RNAi plasmid of PttGA20-oxidase gene was successfully constructed.[Conclusion] The experiment provided a new way for culturing dwarfed plant.
文摘Gibberellin 3-oxidase catalyzes the conversion of inactive gibberellin(GA) species into GAs with biological activity and it is subjected to strict developmental controls in the life cycle of a plant. In this study, 33 gene sequences, encoding the gibberellin 3-oxidase(GA3ox) from Dasypyrum villosum and its dwarf mutant, were obtained. Each contained a 1 107 bp coding sequence(CDS) that encoded a putative protein containing 369 amino acids. The GA3ox protein showed 77% to 97% homology and shared the major conserved structural domains of GA3ox proteins with rice, sorghum bicolor, oat, barley, and wheat. Sequence alignment showed that there were 20 single nucleotide polymorphisms(SNPs) and 22 Insertion/deletions(In Dels) among these sequences, which could be divided into 2 haplotypes, haplotypes Ⅰ and Ⅱ. Haplotype Ⅰ was found in the wild type and was1 495 bp in length, and haplotype Ⅱ was found in the dwarf mutant and was 1 485 bp in length. The Q-PCR results showed that GA3ox was expressed in the leaves, roots, internodes, and stem nodes, and that there was a significant difference in the transcript level of the GA3ox between the wild type and dwarf mutant. The transcript levels of GA3ox in the leaves at the seedling stage, stem elongation stage and the heading stage, in the root and stem nodes at the stem elongation stage and in the internodes at the heading stage of the wild type, were significantly higher than those in the dwarf mutant. However, GA3ox expression in the rest of the wild type tissues at the 3 stages was slightly higher than or not different from the dwarf mutant.The results suggested that the wild type and mutant allele sequences of GA3ox in D. villosum showed 2 amino acid changes in exons and variations in the lengths of introns or the SNPs in introns, which most probably impaired the function of the enzyme,affected the GA3ox expression level, and eventually gave rise to dwarfing.
基金supported by grants from the China Agriculture Research System(CARS-28-14)the Technical System of Fruit Industry in Anhui Province,China(AHCYTX-10)the Scientific Research Projects for Postgraduates of Anhui Universities,China(YJS20210207).
文摘Drought stress is a devastating natural disaster driven by the continuing intensification of global warming,which seriously threatens the productivity and quality of several horticultural crops,including pear.Gibberellins(GAs)play crucial roles in plant growth,development,and responses to drought stress.Previous studies have shown significant reductions of GA levels in plants under drought stress;however,our understanding of the intrinsic regulation mechanisms of GA-mediated drought stress in pear remains very limited.Here,we show that drought stress can impair the accumulation of bioactive GAs(BGAs),and subsequently identified PbrGA2ox1 as a chloroplast-localized GA deactivation gene.This gene was significantly induced by drought stress and abscisic acid(ABA)treatment,but was suppressed by GA_(3)treatment.PbrGA2ox1-overexpressing transgenic tobacco plants(Nicotiana benthamiana)exhibited enhanced tolerance to dehydration and drought stresses,whereas knock-down of PbrGA2ox1 in pear(Pyrus betulaefolia)by virus-induced gene silencing led to elevated drought sensitivity.Transgenic plants were hypersensitive to ABA,and had a lower BGAs content,enhanced reactive oxygen species(ROS)scavenging ability,and augmented ABA accumulation and signaling under drought stress compared to wild-type plants.However,the opposite effects were observed with PbrGA2ox1 silencing in pear.Moreover,exogenous GA_(3)treatment aggravated the ROS toxic effect and restrained ABA synthesis and signaling,resulting in the compromised drought tolerance of pear.In summary,our results shed light on the mechanism by which BGAs are eliminated in pear leaves under drought stress,providing further insights into the mechanism regulating the effects of GA on the drought tolerance of plants.
基金supported by grants from the Ministry of Sciences and Technology of China (No. 2005CB120805 and 2006AA10A101)the National Natural Science Foundation of China (No. 30621001 and 30871512)
文摘Gibberellin （GA） 2-oxidase plays a key role in the GA catabolic pathway through 2β-hydroxylation.In the present study,we isolated a CaMV 35S-enhancer activation tagged mutant,H032.This mutant exhibited a dominant dwarf and GA-deficient phenotype,with a final stature that was less than half of its wild-type counterpart.The endogenous bioactive GAs are markedly decreased in the H032 mutant,and application of bioactive GAs （GA3 or GA4） can reverse the dwarf phenotype.The integrated T-DNA was detected 12.8 kb upstream of the OsGA2ox6 in the H032 genome by TAIL-PCR.An increased level of OsGA2ox6 mRNA was detected at a high level in the H032 mutant,which might be due to the enhancer role of the CaMV 35S promoter.RNAi and ectopic expression analysis of OsGA2ox6 indicated that the dwarf trait and the decreased levels of bioactive GAs in the H032 mutant were a result of the up-regulation of the OsGA2ox6 gene.BLASTP analysis revealed that OsGA2ox6 belongs to the class III of GA 2-oxidases,which is a novel type of GA2ox that uses C20-GAs （GA12 and/or GA53） as the substrates.Interestingly,we found that a GA biosynthesis inhibitor,paclobutrazol,positively regulated the OsGA2ox6 gene.Unlike the over-expression of OsGA2ox1,which led to a high rate of seed abortion,the H032 mutant retained normal flowering and seed production.These results indicate that OsGA2ox6 mainly affects plant stature,and the dominant dwarf trait of the H032 mutant can be used as an efficient dwarf resource in rice breeding.
基金funded by The National Key Research and Development Program of China(grant nos.2021YFF1000101 to S.H.and 2022YFD1200300 to X.D.)the National Natural Science Foundation of China(grant no.32122062 to S.H.)the Agricultural Science,Technology Innovation Program of the Chinese Academy of Agricultural Sciences and Henan Provincial Department of Science and Technology research project(grant no.232102111076).
文摘Optimal plant height is crucial in modern agriculture, influencing lodging resistance and facilitating mechanized crop production. Upland cotton (Gossypium hirsutum) is the most important fiber crop globally;however, the genetic basis underlying plant height remains largely unexplored. In this study, we conducted a genome-wide association study to identify a major locus controlling plant height (PH1) in upland cotton. This locus encodes gibberellin 2-oxidase 1A (GhPH1) and features a 1133-bp structural variation (PAVPH1) located approximately 16 kb upstream. The presence or absence of PAVPH1 influences the expression of GhPH1, thereby affecting plant height. Further analysis revealed that a gibberellin-regulating transcription factor (GhGARF) recognizes and binds to a specific CATTTG motif in both the GhPH1 promoter and PAVPH1. This interaction downregulates GhPH1, indicating that PAVPH1 functions as a distant upstream silencer. Intriguingly, we found that DWARF53 (D53), a key repressor of the strigolactone (SL) signaling pathway, directly interacts with GhGARF to inhibit its binding to targets. Moreover, we identified a previously unrecognized gibberellin-SL crosstalk mechanism mediated by the GhD53-GhGARF-GhPH1/PAVPH1 module, which is crucial for regulating plant height in upland cotton. These findings shed light on the genetic basis and gene interaction network underlying plant height, providing valuable insights for the development of semi-dwarf cotton varieties through precise modulation of GhPH1 expression.
基金supported by the Agricultural Variety Improvement Project of Shandong Province(2019LZGC010)the National Key Research and Development Program of China(2019YFD1002701).
文摘Alfalfa(Medicago sativa L.)is a nutritious forage crop with wide ecological adaptability.The molecular breeding of alfalfa is restricted by its heterozygous tetraploid genome and the difficult genetic manipulation process.Under time and resource constraints,we applied a more convenient approach.We investigated two MtGA3ox genes,MtGA3ox1 and MtGA3ox2,of Medicago truncatula,a diploid legume model species,finding that MtGA3ox1 plays a major role in GA-regulated plant architecture.Mutation of neither gene affected nitrogenase activity.These results suggest that MtGA3ox1 can be used in semidwarf and prostrate alfalfa breeding.Based on the M.truncatula MtGA3ox1 sequence,MsGA3ox1 was cloned from alfalfa,and two knockout targets were designed.An efficient CRISPR/Cas9-based genome editing protocol was used to generate msga3ox1 mutants in alfalfa.We obtained three lines that carried mutations in all four alleles in the T0 generation.Fifteen clonal plants were vegetatively propagated from each transgenic line using shoot cuttings.The plant height and internode length of msga3ox1 null mutants were significantly decreased.The number of total lateral branches,leaf/stem ratio and crude protein content of aerial plant parts of msga3ox1 mutants were significantly increased.Thus,we obtained semi-dwarf and prostrate alfalfa by gene editing.
基金Supported by the Southeast University Foundation for Excellent Young Scholars(4023001013).
文摘Senescence is the process of programmed degradation. The G2 line of pea exhibits apical senescence-delaying phenotype under short-day （SD） conditions, but the mechanism regulating the apical senescence is still largely unknown. Gibberellin （GA） was proved to be able to delay this apical senescence phenotype in G2 pea grown under long-day （LD） conditions. Here we show that the initiation of cell death signals in the terminal floral meristem was involved in the regulation of apical senescence in pea plants. SD signals prevented the formation of the cell death region in the apical mersitem. Moreover, GA3 treatment could effectively inhibit the occurrence of cell death-mediated apical senescence in LD-grown apical buds. Therefore, our data suggest that the prevention of apical senescence in SD-grown G2 pea through GA3 treatment may be largely responsible for the regulation of occurrence of the DNA fragmentation in apical meristem.
基金Project supported by the China Agriculture Research System(No.CARS-25)the Program for Liaoning Innovative Research Team in University(No.LZ2015025)the Program for Liaoning Key Laboratory(No.LZ2015064),China
文摘Tomato is an ideal model species for fleshy fruit development research. Sl YABBY2 b regulates the ovary locule number, which is increased by gibberellins, in tomato. However, the relationship between Sl YABBY2 b and endogenous gibberellin is poorly understood. In this study, Sl YABBY2 b-overexpressing and RNA interference(RNAi) transgenic tomato plants were used to elucidate the mechanism by which Sl YABBY2 b regulates the ovary locule number and endogenous gibberellin content in tomato. Sl YABBY2 b-overexpressing plants showed fewer locules and lower gibberellin content than the control plants. Contrasting results were found in the RNAi lines. Therefore, the Sl YABBY2 b gene negatively regulates tomato ovary locule number and endogenous gibberellin content. Furthermore, the expression of Sl YABBY2 b gene was remarkably higher than that of the wild type in the apical shoots of gibberellindeficient mutants. This showed that the gibberellins can inhibit the expression of Sl YABBY2 b gene negative regulation. Further study revealed that Sl YABBY2 b suppressed the expression of Sl GA20 ox1 and Sl GA3 ox2, but increased that of Sl GA2 ox1 and Sl GA2 ox5 in the apical shoots of Sl YABBY2 b-overexpressing plants, thereby reducing gibberellin content. Contrasting results were found in the RNAi lines. Our results showed that the Sl YABBY2 b gene was located on gibberellin signal transduction pathways, fed back regulation of the synthesis of gibberellin, and felt exogenous gibberellin signal to further regulate the formation of tomato locule.
基金the ‘Large-scale Instrument and Equipment Sharing Foundation of Wuhan University’ for supporting the use of the instruments in the College of Life Sciences in Wuhan Universitysupported by grants to Y.W. from Nation Natural Science Foundation of China (31270333 and 90817013)the Major State Basic Research Program from the Ministry of Science and Technology of China (2013CB126900)
文摘The phytohormones gibberellic acid （GA） and abscisic acid （ABA） antagonistically control seed germina- tion. High levels of GA favor seed germination, whereas high levels of ABA hinder this process. The direct relationship between GA biosynthesis and seed germina- tion ability need further investigation. Here, we identified the ABA-insensitive gain-of-function mutant germination insensitive to ABA mutant 2 （gim2） by screening a population of XVE T-DNA-tagged mutant lines. Based on two loss-of-function gim2-ko mutant lines, the disruption of GIM2 function caused a delay in seed germination. By contrast, upregulation of GIM2 accelerated seed germina- tion, as observed in transgenic lines overexpressing GIM2 （OE）. We detected a reduction in endogenous bioactive GA levels and an increase in endogenous ABA levels in the gim2-ko mutants compared to wild type. Conversely, the OE lines had increased endogenous bioactive GA levels and decreased endogenous ABA levels. The expression levels of a set of GA- and]or ABA-related genes were altered in both the gim2-ko mutants and the OE lines. We confirmed that GIM2 has dioxygenase activity using an in vitro enzyme assay, observing that GIM2 can oxidize GA^2. Hence, our characterization of GIM2 demonstrates that it plays a role in seed germination by affecting the GA metabolic pathway in Arabidopsis.
