Seed germination is a crucial checkpoint for plant survival under unfavorable environmental conditions. Ab- scisic acid （ABA） signaling plays a vital role in integrating environmental information to regulate seed ge...Seed germination is a crucial checkpoint for plant survival under unfavorable environmental conditions. Ab- scisic acid （ABA） signaling plays a vital role in integrating environmental information to regulate seed germination. It has been well known that MCMI/AGAMOUS/DEFICIENS/SRF （MADS）-box transcription factors are key regulators of seed and flower development in Arabidopsis. However, little is known about their functions in seed germination. Here we report that MADS-box transcription factor AGL21 is a negative regulator of seed germination and post-germination growth by controlling the expression of ABA-INSENSITIVE 5 （ABIb＇） in Arabidopsis. The AGL21-overexpressing plants were hypersensitive to ABA, salt, and osmotic stresses during seed germination and early post-germination growth, whereas ag121 mutants were less sensitive. We found that AGL21 positively regulated ABI5 expression in seeds. Consistently, genetic analyses showed that AGL21 is epistatic to ABI5 in controlling seed germination. Chromatin immunoprecipitation assays further demonstrated that AGL21 could directly bind to the ABI5 promoter in plant cells. Moreover, we found that AGL21 responded to multiple environmental stresses and plant hormones during seed germination. Taken together, our results suggest that AGL21 acts as a surveillance integrator that incorporates environmental cues and endogenous hormonal signals into ABA signaling to regulate seed germination and early post-germination growth.展开更多
WD40 repeat-containing proteins(WD40 proteins)serve as versatile scaffolds for protein-protein interac-tions,modulating a variety of cellular processes such as plant stress and hormone responses.Here we report the ide...WD40 repeat-containing proteins(WD40 proteins)serve as versatile scaffolds for protein-protein interac-tions,modulating a variety of cellular processes such as plant stress and hormone responses.Here we report the identification of a WD40 protein,XIW1(for XPO1-interacting WD40 protein 1),which positively regulates the abscisic acid(ABA)response in Arabidopsis.XIW1 is located in the cytoplasm and nucleus.We found that it interacts with the nuclear transport receptor XPO1 and is exported by XPO1 from the nucleus.Mutation of XIW1 reduces the induction of ABA-responsive genes and the accumulation of ABA Insensitive 5(ABI5),causing mutant plants with ABA-insensitive phenotypes during seed germination and seedling growth,and decreased drought stress resistance.ABA treatment upregulates the expression of XIW1,and both ABA and abiotic stresses promote XIW1 accumulation in the nucleus,where it interacts with ABI5.Loss of XIW1 function results in rapid proteasomal degradation of ABI5.Taken together,these findings suggest that XIW1 is a nucleocytoplasmic shuttling protein and plays a positive role in ABA responses by interacting with and maintaining the stability of ABI5 in the nucleus.展开更多
Due to its tropical origins,rice(Oryza sativa)is susceptible to cold stress,which poses severe threats to production.OsNAC5,a NAC-type transcription factor,participates in the cold stress response of rice,but the deta...Due to its tropical origins,rice(Oryza sativa)is susceptible to cold stress,which poses severe threats to production.OsNAC5,a NAC-type transcription factor,participates in the cold stress response of rice,but the detailed mechanisms remain poorly understood.Here,we demonstrate that OsNAC5 positively regulates cold tolerance at germination and in seedlings by directly activating the expression of ABSCISIC ACID INSENSITIVE 5(OsABI5).Haplotype analysis indicated that single nucleotide polymorphisms in a NAC-binding site in the OsABI5 promoter are strongly associated with cold tolerance.OsNAC5 also enhanced OsABI5 stability,thus regulating the expression of cold-responsive(COR)genes,enabling fine-tuned control of OsABI5 action for rapid,precise plant responses to cold stress.DNA affinity purification sequencing coupled with transcriptome deep sequencing identified several OsABI5 target genes involved in COR expression,including DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR 1A(OsDREB1A),OsMYB20,and PEROXIDASE 70(OsPRX70).In vivo and in vitro analyses suggested that OsABI5 positively regulates COR gene transcription,with marked COR upregulation in OsNAC5-overexpressing lines and downregulation in osnac5 and/or osabi5 knockout mutants.This study extends our understanding of cold tolerance regulation via OsNAC5 through the OsABI5-CORs transcription module,which may be used to ameliorate cold tolerance in rice via advanced breeding.展开更多
Seed viability is an essential feature for genetic resource conservation as well as sustainable crop production.Long-term storage induces seed viability deterioration or seed aging,accompanied by the accumulation of t...Seed viability is an essential feature for genetic resource conservation as well as sustainable crop production.Long-term storage induces seed viability deterioration or seed aging,accompanied by the accumulation of toxic reactive oxygen species(ROS)to suppress seed germination.Controlled deterioration treatment(CDT)is a gen-eral approach for mimicking seed aging.The transcription factor ANAC089 was previously reported to modulate seed primary germination.In this study,we evaluated the ability of ANAC089 to control seed viability during aging.Compared with that in the wild-type line,the mutation of ANAC089 significantly increased H_(2)O_(2),thereby reducing seed viability after CDT,while the overexpression of ANAC089 reduced H_(2)O_(2) and improved seed long-evity,indicating a critical role for ANAC089 in maintaining seed viability through H_(2)O_(2) signaling.A series of stu-dies have shown that ANAC089 targets and negatively regulates the level of ABI5,an important transmitter of abscisic acid(ABA)signals,to affect seed viability after CDT.Furthermore,ABI5 negatively regulated the expres-sion of VTC2,which is involved in the biosynthesis of the antioxidant ascorbic acid and H_(2)O_(2) scavenging.As a result,ANAC089 attenuates the generation of H_(2)O_(2),thereby enhancing seed viability through the ABI5-VTC2 module during the seed aging process.Taken together,our results reveal a novel mechanism by which ANAC089 enhances seed viability by coordinating ABI5 and VTC2 expression,ultimately preventing the overac-cumulation of H_(2)O_(2),which would have led to reduced seed viability.展开更多
In Arabidopsis, the phytohormone abscisic acid （ABA） plays a vital role in inhibiting seed germination and in postgermination seedling establishment. In the ABA signaling pathway, ABI5, a basic Leu zipper transcript...In Arabidopsis, the phytohormone abscisic acid （ABA） plays a vital role in inhibiting seed germination and in postgermination seedling establishment. In the ABA signaling pathway, ABI5, a basic Leu zipper transcription factor, has important functions in the regulation of seed germination. ABI5 protein localizes in nuclear bodies, along with AFP, COP1, and SIZ1, and was degraded through the 26S proteasome pathway. However, the mechanisms of ABI5 nuclear body formation and ABI5 protein degradation remain obscure. In this study, we found that the Arabidopsis CROWDED NUCLEI （CRWN） proteins, predicted nuclear matrix proteins essential for maintenance of nuclear morphology, also participate in ABA-controlled seed germination by regulating the degradation of ABI5 protein. During seed germination, the crwn mutants are hypersensitive to ABA and have higher levels of ABI5 protein compared to wild type. Genetic analysis suggested that CRWNs act upstream of ABIS. The observation that CRWN3 colocalizes with ABI5 in nuclear bodies indicates that CRWNs might participate in ABI5 protein degrada- tion in nuclear bodies. Moreover, we revealed that the extreme C-terminal of CRWN3 protein is necessary for its function in the response to ABA in germination. Our results suggested important roles of CRWNs in ABI5 nuclear body organization and ABI5 protein degradation during seed germination.展开更多
PHYTOCHROME-INTERACTING FACTORS(PIFs)are a group of basic helix-loop-helix transcription factors that can physically interact with photoreceptors,including phytochromes and cryptochromes.It was previously demonstrated...PHYTOCHROME-INTERACTING FACTORS(PIFs)are a group of basic helix-loop-helix transcription factors that can physically interact with photoreceptors,including phytochromes and cryptochromes.It was previously demonstrated that PIFs accumulated in darkness and repressed seedling photomorphogenesis,and that PIFs linked different photosensory and hormonal pathways to control plant growth and development.In this study,we show that PIFs positively regulate the ABA signaling pathway during the seedling stage specifically in darkness.We found that PIFs positively regulate ABI5 transcript and protein levels in darkness in response to exogenous ABA treatment by binding directly to the G-box motifs in the ABI5 promoter.Consistently,PIFs and the G-box motifs in the ABI5 promoter determine ABI5 expression in darkness,and overexpression of ABI5 could rescue the ABA-insensitive phenotypes of pifq mutants in the dark.Moreover,we discovered that PIFs can physically interact with the ABA receptors PYL8 and PYL9,and that this interaction is not regulated by ABA.Further analyses showed that PYL8 and PYL9 promote PIF4 protein accumulation in the dark and enhance PIF4 binding to the ABI5 promoter,but negatively regulate PIF4-mediated ABI5 activation.Taken together,our data demonstrate that PIFs interact with ABA receptors to orchestrate ABA signaling in darkness by controlling ABI5 expression,providing new insights into the pivotal roles of PIFs as signal integrators in regulating plant growth and development.展开更多
植物激素脱落酸（abscisic acid,ABA）在植物生长、发育及环境胁迫中起着重要的作用。本研究发现拟南芥PKSes（SOS2-like protein kinases）蛋白激酶家族成员PKS5（SOS2-like protein kinase 5）参与植物ABA响应。PKS5功能获得性点突变...植物激素脱落酸（abscisic acid,ABA）在植物生长、发育及环境胁迫中起着重要的作用。本研究发现拟南芥PKSes（SOS2-like protein kinases）蛋白激酶家族成员PKS5（SOS2-like protein kinase 5）参与植物ABA响应。PKS5功能获得性点突变体pks5-3与pks5-4表现出对ABA的敏感表型。在外源ABA处理下,pks5-3与pks5-4种子萌发率降低,幼苗生长矮小、黄化。体外磷酸化测试显示,PKS5特异磷酸化ABA响应元件ABI5（ABA-insensitive 5）N末端多肽（1~211 aa）。q RT-PCR分析表明pks5-3与pks5-4突变体中ABI5下游ABA响应基因RAB18（RESPONSIVE TO ABA18）与EM6（LATE EMBRYOGENESIS ABUNDANT 6）表达均发生改变。这些研究结果表明,拟南芥PKS5通过磷酸化ABI5的N末端参与植物ABA响应过程。展开更多
The bZIP transcription factor ABSCISIC ACID INSENSITIVE5(ABI5)is a master regulator of seed germination and post-germinative growth in response to abscisic acid(ABA),but the detailed molecularmechanism by which it rep...The bZIP transcription factor ABSCISIC ACID INSENSITIVE5(ABI5)is a master regulator of seed germination and post-germinative growth in response to abscisic acid(ABA),but the detailed molecularmechanism by which it represses plant growth remains unclear.In this study,we used proximity labeling to map the neighboring proteome of ABI5 and identified FCS-LIKE ZINC FINGER PROTEIN 13(FLZ13)as a novel ABI5 interaction partner.Phenotypic analysis of flz13 mutants and FLZ13-overexpressing lines demonstrated that FLZ13 acts as a positive regulator of ABA signaling.Transcriptomic analysis revealed that both FLZ13 and ABI5 downregulate the expression of ABA-repressed and growth-related genes involved in chlorophyll biosynthesis,photosynthesis,and cell wall organization,thereby repressing seed germination and seedling establishment in response to ABA.Further genetic analysis showed that FLZ13 and ABI5 function together to regulate seed germination.Collectively,our findings reveal a previously uncharacterized transcriptional regulatorymechanismby which ABA mediates inhibition of seed germination and seedling establishment.展开更多
Hd3a(Heading date 3a)是拟南芥成花素基因FT(Flowering Locus T)的同源基因,作为水稻开花的强诱导因子,对短日照条件下水稻的开花具有重要的促进作用。Hd3a在水稻发育中是否具有其他功能,目前的认识仍非常有限。在我们的研究中,通过对H...Hd3a(Heading date 3a)是拟南芥成花素基因FT(Flowering Locus T)的同源基因,作为水稻开花的强诱导因子,对短日照条件下水稻的开花具有重要的促进作用。Hd3a在水稻发育中是否具有其他功能,目前的认识仍非常有限。在我们的研究中,通过对Hd3a基因组序列进行生物信息学分析,发现Hd3a的启动子序列包含响应脱落酸(Abscisic Acid,ABA)信号的ABRE(ABA-Responsive Element)元件。荧光素酶发光反应和RT-qPCR分析都证实了Hd3a的转录表达随外源ABA增加而减少。通过不同浓度的ABA处理水稻野生型和hd3a缺失突变体种子,结果表明hd3a缺失突变体种子萌发明显被抑制,暗示了Hd3a缺失导致种子萌发中对ABA敏感性增强,同时hd3a突变体中ABA信号途径响应基因ABI5(ABA Insensitive 5)、ABL1(ABI5-Like1)的表达量升高,表明Hd3a可负调控ABA信号。综上所述,Hd3a可以响应ABA信号调控水稻种子萌发,这些研究结果对于深入理解水稻Hd3a基因的生物学功能具有重要意义。展开更多
Seed germination or dormancy status is strictly controlled by endogenous phytohormone and exogenous environment signals.Abscisic acid(ABA)is the important phytohormone to suppress seed germination.Ambient high tempera...Seed germination or dormancy status is strictly controlled by endogenous phytohormone and exogenous environment signals.Abscisic acid(ABA)is the important phytohormone to suppress seed germination.Ambient high temperature(HT)also suppressed seed germination,or called as secondary seed dormancy,through upregulating ABI5,the essential component of ABA signal pathway.Previous result shows that appropriate nitric oxide(NO)breaks seed dormancy through triggering S-nitrosoglutathion reductase(GSNOR1)-dependent S-nitrosylation modification of ABI5 protein,subsequently inducing the degradation of ABI5.Here we found that HT induced the degradation of GSNOR1 protein and reduced its activity,thus accumulated more reactive nitrogen species(RNS)to damage seeds viability.Furthermore,HT increased the S-nitrosylation modification of GSNOR1 protein,and triggered the degradation of GSNOR1,therefore stabilizing ABI5 to suppress seed germination.Consistently,the ABI5 protein abundance was lower in the transgenic line overexpressing GSNOR1,but higher in the gsnor mutant after HT stress.Genetic analysis showed that GSNOR1 affected seeds germination through ABI5 under HT.Taken together,our data reveals a new mechanism by which HT triggers the degradation of GSNOR1,and thus stabilizing ABI5 to suppress seed germination,such mechanism provides the possibility to enhance seed germination tolerance to HT through genetic modification of GNSOR1.展开更多
MED25 has been implicated as a negative regulator of the abscisic acid(ABA)signaling pathway.However,it is unclear whether other Mediator subunits could associate with MED25 to participate in the ABA response.Here,we ...MED25 has been implicated as a negative regulator of the abscisic acid(ABA)signaling pathway.However,it is unclear whether other Mediator subunits could associate with MED25 to participate in the ABA response.Here,we used affinity purification followed by mass spectrometry to uncover Mediator subunits that associate with MED25 in transgenic plants.We found that at least26 Mediator subunits,belonging to the head,middle,tail,and CDK8 kinase modules,were copurified with MED25 in vivo.Interestingly,the tail module subunit MED16 was identified to associate with MED25 under both mock and ABA treatments.We further showed that the disruption of MED16 led to reduced ABA sensitivity compared to the wild type.Transcriptomic analysis revealedthattheexpressionofseveral ABA-responsive genes was significantly lower in med16 than those in wild type.Furthermore,we discovered that MED16 may possibly compete with MED25 to interact with the key transcription factor ABA INSENSITIVE 5(ABI5)to positively regulate ABA signaling.Consistently,med16 and med25 mutants displayed opposite phenotypes in ABA response,cuticle permeability,and differential ABI5-mediated EM1 and EM6 expression.Together,our data indicate that MED16 and MED25 differentially regulate ABA signaling byantagonisticallyaffectingABI5-mediated transcription in Arabidopsis.展开更多
The transcription factor ABSCISIC ACID INSENSITIVE5(ABI5)plays a crucial role in abscisic acid(ABA)signaling during seed germination.However,how ABI5 is regulated during this process is poorly understood.Here,we repor...The transcription factor ABSCISIC ACID INSENSITIVE5(ABI5)plays a crucial role in abscisic acid(ABA)signaling during seed germination.However,how ABI5 is regulated during this process is poorly understood.Here,we report that the ubiquitin E3 ligase MIEL1 and its target transcription factor MYB30 modulate ABA responses in Arabidopsis thaliana during seed germination and seedling establishment via the precise regulation of ABI5.MIEL1 interacts with and ubiquitinates ABI5 to facilitate its degradation during germination.The transcription factor MYB30,whose turnover is mediated by MIEL1 during seed germination,also interacts with ABI5 to interfere with its transcriptional activity.MYB30 functions downstream of MIEL1 in the ABA response,and both are epistatic to ABI5 in ABA-mediated inhibition of seed germination and postgerminative growth.ABA treatment induces the degradation of MIEL1 and represses the interaction between MIEL1 and ABI5/MYB30,thus releasing both ABI5 and MYB30.Our results demonstrate that MIEL1 directly mediates the proteasomal degradation of ABI5 and inhibits its activity via the release of its target protein MYB30,thus ensuring precise ABA signaling during seed germination and seedling establishment.展开更多
基金This work was supported by the China National Natural Science Funds for Distinguished Young Scholar （grant no. 31500231 to L.-H.Yo）, China Postdoctoral Science Foundation, No.9 Special Fund （grant no. 2016T90577 to L.-H.Y.）, and Chinese Academy of Sciences （grant no. KSCX3-EW-N- 07 to C.-B.X.）.
文摘Seed germination is a crucial checkpoint for plant survival under unfavorable environmental conditions. Ab- scisic acid （ABA） signaling plays a vital role in integrating environmental information to regulate seed germination. It has been well known that MCMI/AGAMOUS/DEFICIENS/SRF （MADS）-box transcription factors are key regulators of seed and flower development in Arabidopsis. However, little is known about their functions in seed germination. Here we report that MADS-box transcription factor AGL21 is a negative regulator of seed germination and post-germination growth by controlling the expression of ABA-INSENSITIVE 5 （ABIb＇） in Arabidopsis. The AGL21-overexpressing plants were hypersensitive to ABA, salt, and osmotic stresses during seed germination and early post-germination growth, whereas ag121 mutants were less sensitive. We found that AGL21 positively regulated ABI5 expression in seeds. Consistently, genetic analyses showed that AGL21 is epistatic to ABI5 in controlling seed germination. Chromatin immunoprecipitation assays further demonstrated that AGL21 could directly bind to the ABI5 promoter in plant cells. Moreover, we found that AGL21 responded to multiple environmental stresses and plant hormones during seed germination. Taken together, our results suggest that AGL21 acts as a surveillance integrator that incorporates environmental cues and endogenous hormonal signals into ABA signaling to regulate seed germination and early post-germination growth.
基金This work was supported by grants from the National Natural Science Foundation of China(31570250)the Science and Technology Project of Guangzhou City,China(201607020006,201804010377)the Natural Science Foundation of Guangdong Province,China(2015A030313410,2017A030313100).
文摘WD40 repeat-containing proteins(WD40 proteins)serve as versatile scaffolds for protein-protein interac-tions,modulating a variety of cellular processes such as plant stress and hormone responses.Here we report the identification of a WD40 protein,XIW1(for XPO1-interacting WD40 protein 1),which positively regulates the abscisic acid(ABA)response in Arabidopsis.XIW1 is located in the cytoplasm and nucleus.We found that it interacts with the nuclear transport receptor XPO1 and is exported by XPO1 from the nucleus.Mutation of XIW1 reduces the induction of ABA-responsive genes and the accumulation of ABA Insensitive 5(ABI5),causing mutant plants with ABA-insensitive phenotypes during seed germination and seedling growth,and decreased drought stress resistance.ABA treatment upregulates the expression of XIW1,and both ABA and abiotic stresses promote XIW1 accumulation in the nucleus,where it interacts with ABI5.Loss of XIW1 function results in rapid proteasomal degradation of ABI5.Taken together,these findings suggest that XIW1 is a nucleocytoplasmic shuttling protein and plays a positive role in ABA responses by interacting with and maintaining the stability of ABI5 in the nucleus.
基金supported by the National Natural Science Foundation of China(32071946 and 32201895)the Research Startup Funding from Hainan Institute of Zhejiang University(0201-6602-A12203)+3 种基金the“Nanhai New Star”Technology Innovation Talent Platform Project of Hainan Province(NHXXRCXM202362)the PhD Scientific Research and Innovation Foundation of Sanya Yazhou Bay Science and Technology City(HSPHDSRF-2023-04-018)the Fundamental Research Funds for the Central Universities(226-2022-00012)the Agriculture Research System of Shanghai,China(202203)。
文摘Due to its tropical origins,rice(Oryza sativa)is susceptible to cold stress,which poses severe threats to production.OsNAC5,a NAC-type transcription factor,participates in the cold stress response of rice,but the detailed mechanisms remain poorly understood.Here,we demonstrate that OsNAC5 positively regulates cold tolerance at germination and in seedlings by directly activating the expression of ABSCISIC ACID INSENSITIVE 5(OsABI5).Haplotype analysis indicated that single nucleotide polymorphisms in a NAC-binding site in the OsABI5 promoter are strongly associated with cold tolerance.OsNAC5 also enhanced OsABI5 stability,thus regulating the expression of cold-responsive(COR)genes,enabling fine-tuned control of OsABI5 action for rapid,precise plant responses to cold stress.DNA affinity purification sequencing coupled with transcriptome deep sequencing identified several OsABI5 target genes involved in COR expression,including DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR 1A(OsDREB1A),OsMYB20,and PEROXIDASE 70(OsPRX70).In vivo and in vitro analyses suggested that OsABI5 positively regulates COR gene transcription,with marked COR upregulation in OsNAC5-overexpressing lines and downregulation in osnac5 and/or osabi5 knockout mutants.This study extends our understanding of cold tolerance regulation via OsNAC5 through the OsABI5-CORs transcription module,which may be used to ameliorate cold tolerance in rice via advanced breeding.
基金supported by the National Natural Science Foundation of China(31970289 to X.H.and 32170562 to P.L.).
文摘Seed viability is an essential feature for genetic resource conservation as well as sustainable crop production.Long-term storage induces seed viability deterioration or seed aging,accompanied by the accumulation of toxic reactive oxygen species(ROS)to suppress seed germination.Controlled deterioration treatment(CDT)is a gen-eral approach for mimicking seed aging.The transcription factor ANAC089 was previously reported to modulate seed primary germination.In this study,we evaluated the ability of ANAC089 to control seed viability during aging.Compared with that in the wild-type line,the mutation of ANAC089 significantly increased H_(2)O_(2),thereby reducing seed viability after CDT,while the overexpression of ANAC089 reduced H_(2)O_(2) and improved seed long-evity,indicating a critical role for ANAC089 in maintaining seed viability through H_(2)O_(2) signaling.A series of stu-dies have shown that ANAC089 targets and negatively regulates the level of ABI5,an important transmitter of abscisic acid(ABA)signals,to affect seed viability after CDT.Furthermore,ABI5 negatively regulated the expres-sion of VTC2,which is involved in the biosynthesis of the antioxidant ascorbic acid and H_(2)O_(2) scavenging.As a result,ANAC089 attenuates the generation of H_(2)O_(2),thereby enhancing seed viability through the ABI5-VTC2 module during the seed aging process.Taken together,our results reveal a novel mechanism by which ANAC089 enhances seed viability by coordinating ABI5 and VTC2 expression,ultimately preventing the overac-cumulation of H_(2)O_(2),which would have led to reduced seed viability.
基金supported by grants from the National Natural Science Foundation(31100211)the Ministry of Science and Technology of China(2014CB943402)
文摘In Arabidopsis, the phytohormone abscisic acid （ABA） plays a vital role in inhibiting seed germination and in postgermination seedling establishment. In the ABA signaling pathway, ABI5, a basic Leu zipper transcription factor, has important functions in the regulation of seed germination. ABI5 protein localizes in nuclear bodies, along with AFP, COP1, and SIZ1, and was degraded through the 26S proteasome pathway. However, the mechanisms of ABI5 nuclear body formation and ABI5 protein degradation remain obscure. In this study, we found that the Arabidopsis CROWDED NUCLEI （CRWN） proteins, predicted nuclear matrix proteins essential for maintenance of nuclear morphology, also participate in ABA-controlled seed germination by regulating the degradation of ABI5 protein. During seed germination, the crwn mutants are hypersensitive to ABA and have higher levels of ABI5 protein compared to wild type. Genetic analysis suggested that CRWNs act upstream of ABIS. The observation that CRWN3 colocalizes with ABI5 in nuclear bodies indicates that CRWNs might participate in ABI5 protein degrada- tion in nuclear bodies. Moreover, we revealed that the extreme C-terminal of CRWN3 protein is necessary for its function in the response to ABA in germination. Our results suggested important roles of CRWNs in ABI5 nuclear body organization and ABI5 protein degradation during seed germination.
基金supported by grants from the National Natural Science Foundation of China(31970262 and 31770321)the Ministry of Agriculture of China for Transgenic Research(2019ZX08010003-002-005)Beijing Outstanding University Discipline Program,and the Recruitm ent Program of Global Youth Experts of China.
文摘PHYTOCHROME-INTERACTING FACTORS(PIFs)are a group of basic helix-loop-helix transcription factors that can physically interact with photoreceptors,including phytochromes and cryptochromes.It was previously demonstrated that PIFs accumulated in darkness and repressed seedling photomorphogenesis,and that PIFs linked different photosensory and hormonal pathways to control plant growth and development.In this study,we show that PIFs positively regulate the ABA signaling pathway during the seedling stage specifically in darkness.We found that PIFs positively regulate ABI5 transcript and protein levels in darkness in response to exogenous ABA treatment by binding directly to the G-box motifs in the ABI5 promoter.Consistently,PIFs and the G-box motifs in the ABI5 promoter determine ABI5 expression in darkness,and overexpression of ABI5 could rescue the ABA-insensitive phenotypes of pifq mutants in the dark.Moreover,we discovered that PIFs can physically interact with the ABA receptors PYL8 and PYL9,and that this interaction is not regulated by ABA.Further analyses showed that PYL8 and PYL9 promote PIF4 protein accumulation in the dark and enhance PIF4 binding to the ABI5 promoter,but negatively regulate PIF4-mediated ABI5 activation.Taken together,our data demonstrate that PIFs interact with ABA receptors to orchestrate ABA signaling in darkness by controlling ABI5 expression,providing new insights into the pivotal roles of PIFs as signal integrators in regulating plant growth and development.
文摘植物激素脱落酸（abscisic acid,ABA）在植物生长、发育及环境胁迫中起着重要的作用。本研究发现拟南芥PKSes（SOS2-like protein kinases）蛋白激酶家族成员PKS5（SOS2-like protein kinase 5）参与植物ABA响应。PKS5功能获得性点突变体pks5-3与pks5-4表现出对ABA的敏感表型。在外源ABA处理下,pks5-3与pks5-4种子萌发率降低,幼苗生长矮小、黄化。体外磷酸化测试显示,PKS5特异磷酸化ABA响应元件ABI5（ABA-insensitive 5）N末端多肽（1~211 aa）。q RT-PCR分析表明pks5-3与pks5-4突变体中ABI5下游ABA响应基因RAB18（RESPONSIVE TO ABA18）与EM6（LATE EMBRYOGENESIS ABUNDANT 6）表达均发生改变。这些研究结果表明,拟南芥PKS5通过磷酸化ABI5的N末端参与植物ABA响应过程。
基金supported by grants from the Open Competition Program of Top Ten Critical Priorities of Agricultural Science and Technology Innovation for the 14th Five-Year Plan of Guangdong Province(2022SDZG05)the National Natural Science Foundation of China(32270291,32061160467,31870171)to C.G.+7 种基金the Youth Innovation Promotion Association,Chinese Academy of Sciences(2023364)the Guangdong Basic and Applied Basic Research Foundation(2022A1515012319)the Guangzhou Basic and Applied Basic Research Foundation(2023A04J0094)to C.Y.the Sub-Project of Chinese Academy of Sciences Pilot Project(XDA24030502)the Guangdong Provincial Special Fund for Modern Agriculture Industry Technology InnovationTeams(2020KJ148)to Y.W.the National Natural Science Foundation of China(32170362),the Guangdong Natural Science Funds for Distinguished Young Scholars(2022B1515020026)the Youth Innovation Promotion Association,Chinese Academy of Sciences(Y2021094)the Fund of South China Botanical Garden,Chinese Academy of Sciences(QNXM-02)to M.L.
文摘The bZIP transcription factor ABSCISIC ACID INSENSITIVE5(ABI5)is a master regulator of seed germination and post-germinative growth in response to abscisic acid(ABA),but the detailed molecularmechanism by which it represses plant growth remains unclear.In this study,we used proximity labeling to map the neighboring proteome of ABI5 and identified FCS-LIKE ZINC FINGER PROTEIN 13(FLZ13)as a novel ABI5 interaction partner.Phenotypic analysis of flz13 mutants and FLZ13-overexpressing lines demonstrated that FLZ13 acts as a positive regulator of ABA signaling.Transcriptomic analysis revealed that both FLZ13 and ABI5 downregulate the expression of ABA-repressed and growth-related genes involved in chlorophyll biosynthesis,photosynthesis,and cell wall organization,thereby repressing seed germination and seedling establishment in response to ABA.Further genetic analysis showed that FLZ13 and ABI5 function together to regulate seed germination.Collectively,our findings reveal a previously uncharacterized transcriptional regulatorymechanismby which ABA mediates inhibition of seed germination and seedling establishment.
文摘Hd3a(Heading date 3a)是拟南芥成花素基因FT(Flowering Locus T)的同源基因,作为水稻开花的强诱导因子,对短日照条件下水稻的开花具有重要的促进作用。Hd3a在水稻发育中是否具有其他功能,目前的认识仍非常有限。在我们的研究中,通过对Hd3a基因组序列进行生物信息学分析,发现Hd3a的启动子序列包含响应脱落酸(Abscisic Acid,ABA)信号的ABRE(ABA-Responsive Element)元件。荧光素酶发光反应和RT-qPCR分析都证实了Hd3a的转录表达随外源ABA增加而减少。通过不同浓度的ABA处理水稻野生型和hd3a缺失突变体种子,结果表明hd3a缺失突变体种子萌发明显被抑制,暗示了Hd3a缺失导致种子萌发中对ABA敏感性增强,同时hd3a突变体中ABA信号途径响应基因ABI5(ABA Insensitive 5)、ABL1(ABI5-Like1)的表达量升高,表明Hd3a可负调控ABA信号。综上所述,Hd3a可以响应ABA信号调控水稻种子萌发,这些研究结果对于深入理解水稻Hd3a基因的生物学功能具有重要意义。
基金funded by the National Natural Science Foundation of China(Grants No.31970289).
文摘Seed germination or dormancy status is strictly controlled by endogenous phytohormone and exogenous environment signals.Abscisic acid(ABA)is the important phytohormone to suppress seed germination.Ambient high temperature(HT)also suppressed seed germination,or called as secondary seed dormancy,through upregulating ABI5,the essential component of ABA signal pathway.Previous result shows that appropriate nitric oxide(NO)breaks seed dormancy through triggering S-nitrosoglutathion reductase(GSNOR1)-dependent S-nitrosylation modification of ABI5 protein,subsequently inducing the degradation of ABI5.Here we found that HT induced the degradation of GSNOR1 protein and reduced its activity,thus accumulated more reactive nitrogen species(RNS)to damage seeds viability.Furthermore,HT increased the S-nitrosylation modification of GSNOR1 protein,and triggered the degradation of GSNOR1,therefore stabilizing ABI5 to suppress seed germination.Consistently,the ABI5 protein abundance was lower in the transgenic line overexpressing GSNOR1,but higher in the gsnor mutant after HT stress.Genetic analysis showed that GSNOR1 affected seeds germination through ABI5 under HT.Taken together,our data reveals a new mechanism by which HT triggers the degradation of GSNOR1,and thus stabilizing ABI5 to suppress seed germination,such mechanism provides the possibility to enhance seed germination tolerance to HT through genetic modification of GNSOR1.
基金supported by the National Natural Science Foundation of China(NSFC 31900238 and NSFC 32070307)to Y.Z.
文摘MED25 has been implicated as a negative regulator of the abscisic acid(ABA)signaling pathway.However,it is unclear whether other Mediator subunits could associate with MED25 to participate in the ABA response.Here,we used affinity purification followed by mass spectrometry to uncover Mediator subunits that associate with MED25 in transgenic plants.We found that at least26 Mediator subunits,belonging to the head,middle,tail,and CDK8 kinase modules,were copurified with MED25 in vivo.Interestingly,the tail module subunit MED16 was identified to associate with MED25 under both mock and ABA treatments.We further showed that the disruption of MED16 led to reduced ABA sensitivity compared to the wild type.Transcriptomic analysis revealedthattheexpressionofseveral ABA-responsive genes was significantly lower in med16 than those in wild type.Furthermore,we discovered that MED16 may possibly compete with MED25 to interact with the key transcription factor ABA INSENSITIVE 5(ABI5)to positively regulate ABA signaling.Consistently,med16 and med25 mutants displayed opposite phenotypes in ABA response,cuticle permeability,and differential ABI5-mediated EM1 and EM6 expression.Together,our data indicate that MED16 and MED25 differentially regulate ABA signaling byantagonisticallyaffectingABI5-mediated transcription in Arabidopsis.
基金supported by the National Natural Science Foundation of China(31872656,32170295,and 31870241)the Natural Science Foundation of Henan(212300410022)the project“the Program for Innovative Research Team(in Science and Technology)in University of Henan Province”(21IRTSTHN019)。
文摘The transcription factor ABSCISIC ACID INSENSITIVE5(ABI5)plays a crucial role in abscisic acid(ABA)signaling during seed germination.However,how ABI5 is regulated during this process is poorly understood.Here,we report that the ubiquitin E3 ligase MIEL1 and its target transcription factor MYB30 modulate ABA responses in Arabidopsis thaliana during seed germination and seedling establishment via the precise regulation of ABI5.MIEL1 interacts with and ubiquitinates ABI5 to facilitate its degradation during germination.The transcription factor MYB30,whose turnover is mediated by MIEL1 during seed germination,also interacts with ABI5 to interfere with its transcriptional activity.MYB30 functions downstream of MIEL1 in the ABA response,and both are epistatic to ABI5 in ABA-mediated inhibition of seed germination and postgerminative growth.ABA treatment induces the degradation of MIEL1 and represses the interaction between MIEL1 and ABI5/MYB30,thus releasing both ABI5 and MYB30.Our results demonstrate that MIEL1 directly mediates the proteasomal degradation of ABI5 and inhibits its activity via the release of its target protein MYB30,thus ensuring precise ABA signaling during seed germination and seedling establishment.
