[目的]油菜素唑抗性因子(brassinazole-resistant,BZR)是植物特有的转录因子,对植物的生长发育起着至关重要的作用.从甜瓜全基因组范围内鉴定CmBZR基因家族成员,分析其相关基因的表达模式,为进一步探究甜瓜BZR基因家族的生物学功能提供基础.[方法]基于甜瓜全基因组数据,通过BLAST对甜瓜BZR家族基因进行鉴定,利用生物信息学的方法分析了该家族蛋白的理化性质、基因染色体分布、基因结构、蛋白质结构域、系统进化以及启动子顺式作用元件,并利用荧光定量PCR验证BZR家族基因在甜瓜不同组织及不同生长发育时期果实中的表达情况.[结果]甜瓜中共鉴定到 6 个BZR基因,系统进化分析可将其分为 5 个亚家族,CmBZR基因分布于第 3、7、8、11 和 12 染色体上.所有的BZR蛋白质都具有保守的结构域.CmBZR基因启动子区域显著富集与生长发育、激素信号转导和非生物逆境胁迫相关的顺式作用元件.CmBEH1-4 在茎、两性花以及子房中高表达,在生长期、成熟期、呼吸跃变期和呼吸跃变后期果实中也均有表达.[结论]在全基因组范围内从甜瓜中系统鉴定出6个甜瓜CmBZR基因家族成员,不同基因在甜瓜的各个组织和不同的生长发育时期均有表达,且表达模式存在差异.

氟溴唑仑(Flub)是一种新型苯二氮?类精神活性物质,其成瘾性及其机制尚不清楚.本研究采用小鼠条件位置偏爱(CPP)模型,研究Flub的奖赏效应,以c-Fos表达评定神经元活性,采用病毒示踪技术追踪神经环路,通过化学遗传技术研究神经环路对奖赏效应的调控作用.结果显示,Flub(ip 3 mg/kg)显著增加小鼠CPP评分,增加腹侧被盖区(VTA)多巴胺(DA)能神经元c-Fos表达.抑制VTA多巴胺能神经元活性,Flub小鼠CPP评分显著降低.病毒示踪显示,VTA多巴胺能神经元接受喙内侧被盖核(RMTg)γ氨基丁酸(GABA)能神经元投射.激活RMTgGABA→VTADA环路或阻断RMTg脑区苯二氮?受体,Flub小鼠的CPP评分显著降低.这些结果表明,Flub通过激活RMTg脑区GABA神经元中的苯二氮?受体,抑制RMTgGABA→VTADA环路,产生奖赏效应.

The growth-promoting hormones brassinosteroids(BRs)and their key signaling component BZR1 play a vital role in balancing normal growth and defense reactions.Here,we discovered that BRs and OsBZR1 up-regulated sakuranetin accumulation and conferred basal defense against Magnaporthe oryzae infection under normal conditions.Resource shortages,including phosphate(Pi)deficiency,potentially disrupt this growth-defense balance.OsSPX1 and OsSPX2 have been reported to sense Pi concentration and interact with the Pi signal mediator OsPHR2,thus regulating Pi starvation responses.In this study,we discovered that OsSPX1/2 interacts with OsBZR1 in both Pi-sufficient and Pi-deficient conditions,inhibit-ing BR-responsive genes.When Pi is sufficient,OsSPX1/2 is captured by OsPHR2,enabling most of OsBZR1 to promote plant growth and maintain basal resistance.In response to Pi starvation,more OsSPX1/2 is released from OsPHR2 to inhibit OsBZR1 activity,resulting in slower growth.Collectively,our study reveals that the OsBZR1-SPX1/2 module balances the plant growth-immunity trade-off in response to Pi availability.

Brassinosteroid(BR)is a vital plant hormone that regulates plant growth and development.BRASSINAZOLE RESISTANT 1(BZR1)is a key transcription factor in BR signaling,and its nucleocytoplasmic localization is crucial for BR signaling.However,the mechanisms that regulate BZR1 nucleocytoplasmic distribution and thus the homeostasis of BR signaling remain largely unclear.The vacuole is the largest organelle in mature plant cells and plays a key role in maintenance of cellular pH,storage of intracellular substances,and transport of ions.In this study,we uncovered a novel mechanism of BR signaling homeostasis regulated by the vacuolar H+-ATPase(V-ATPase)and BZR1 feedback loop.Our results revealed that the vha-a2 vha-a3 mutant(vha2,lacking V-ATPase activity)exhibits enhanced BR signaling with increased total amount of BZR1,nuclear-localized BZR1,and the ratio of BZR1/phosphorylated BZR1 in the nucleus.Further biochemical assays re-vealed that VHA-a2 and VHA-a3 of V-ATPase interact with the BZR1 protein through a domain that is conserved across multiple species.VHA-a2 and VHA-a3 negatively regulate BR signaling by interacting with BZR1 and promoting its retention in the tonoplast.Interestingly,a series of molecular analyses demon-strated that nuclear-localized BZR1 could bind directly to specific motifs in the promoters of VHA-a2 and VHA-a3 to promote their expression.Taken together,these results suggest that V-ATPase and BZR1 may form a feedback regulatory loop to maintain the homeostasis of BR signaling in Arabidopsis,providing new insights into vacuole-mediated regulation of hormone signaling.

The BAP module,comprising BRASSINAZOLE RESISTANT 1(BZR1),AUXIN RESPONSE FACTOR 6(ARF6),and PHYTOCHROME-INTERACTING FACTOR 4(PIF4),functions as a molecular hub to orchestrate plant growth and development.In Arabidopsis thaliana,components of the BAP module physically interact to form a complex system that integrates light,brassinosteroid(BR),and auxin signals.Little is known about the origin and evolution of the BAP module.Here,we con-ducted comparative genomic and transcriptomic analyses to investigate the evolution and func-tional diversification of the BAP module.Our re-sults suggest that the BAP module originated in land plants and that the ζ,ε,and γ whole-genome duplication/triplication events contributed to the expansion of BAP module components in seed plants.Comparative transcriptomic analysis suggested that the prototype BAP module arose in Marchantia polymorpha,experienced stepwise evolution,and became established as a mature regulatory system in seed plants.We developed a formula to calculate the signal transduction pro-ductivity of the BAP module and demonstrate that more crosstalk among components enables higher signal transduction efficiency.Our results reveal the evolutionary history of the BAP module and provide insights into the evolution of plant signaling networks and the strategies employed by plants to integrate environmental and endog-enous signals.

Inorganic phosphate(Pi)availability is an important factor which affects the growth and yield of crops,thus an appropriate and effective response to Pi fluctuation is critical.However,how crops orches-trate Pi signaling and growth under Pi starvation conditions to optimize the growth defense tradeoff remains unclear.Here we show that a Pi starvation-induced transcription factor NIGT1(NITRATE-INDUCIBLE GARP-TYPE TRANSCRIPTIONAL RE-PRESSOR 1)controls plant growth and prevents a hyper-response to Pi starvation by directly repressing the expression of growth-related and Pi-signaling genes to achieve a balance between growth and response under a varying Pi environ-ment.NIGT1 directly binds to the promoters of Pi starvation signaling marker genes,like IPS1,miR827,and SPX2,under Pi-deficient conditions to mitigate the Pi-starvation responsive(PSR).It also directly represses the expression of vacuolar Pi efflux transporter genes VPE1/2 to regulate plant Pi ho-meostasis.We further demonstrate that NIGT1 con-strains shoot growth by repressing the expression of growth-related regulatory genes,including brassi-nolide signal transduction master regulator BZR1,cell division regulator CYCB1;1,and DNA replication regulator PSF3.Our findings reveal the function of NIGT1 in orchestrating plant growth and Pi starva-tion signaling,and also provide evidence that NIGT1 acts as a safeguard to avoid hyper-response during Pi starvation stress in rice.

The steroid hormone brassinosteroid (BR) plays a broad role in plant growth and development.As the retarded growth in BR-insensitive and BR-deficient mutants causes a strong delay in days to flowering,BR signaling has been thought to promote the floral transition inArabidopsis.In this study,using a developmental measure of flowering time,we show that BR signaling inhibits the floral transition and promotes vegetative growth in the Arabidopsis accessions Columbia and Enkheim-2.We found that BR signaling promotes the expression of the potent floral repressor FLOWERING LOCUS C (FLC) and three FLC homologs to inhibit flowering.In the presence of BR,the transcription factor BRASSlNAZOLE-RESlSTANT1 (BZR1),together with BES1-INTERACTING MYC-like proteins (BIMs),specifically binds a BR-responsive element in the first intron of FLC and further recruits a histone 3 lysine 27 (H3K27) demethylase to downregulate levels of the repressive H3K27 trimethylation mark and thus antagonize Polycomb silencing at FLC,leading to its activation.Taken together,our findings demonstrate that BR signaling inhibits the floral transition inArabidopsis by a novel molecular mechanism in which BR signals are transduced into FLC activation and consequent floral repression.

对甘蓝型油菜(Brassica napus L.)与拟南芥(Arabidopsis thaliana L.)中保守的油菜素甾醇(Brassinosteroids,BR)信号相关基因进行对比分析,并以甘蓝型油菜品种‘沪油15’为材料,对BR信号通路相关同源基因进行了组织表达分析.结果显示,BR合成基因与信号组分在花和幼嫩种子中表达量更高;低浓度BR处理可以促进幼苗根的生长,高浓度BR处理则起抑制作用;BR合成抑制剂(Brassinozole,BRZ)处理可抑制黑暗条件下幼苗下胚轴的伸长;BR处理可以降低BR合成基因的表达水平,而BRZ处理则相反,表明甘蓝型油菜中BR信号增加能反馈抑制BR的合成.烟草(Nicotiana tabacum L.)瞬时表达实验结果发现,与拟南芥BZR1基因同源的甘蓝型油菜BnBZL2编码蛋白定位在细胞质和细胞核中,BR处理可增加BnBZL2的核定位.蛋白质免疫印迹检测结果显示,BR处理可增加去磷酸化BnBZL2的比例.本研究进一步模拟了拟南芥bzr1-1D功能获得性突变体对BnBZL2蛋白进行点突变(BnBZL2*),并构建载体转化拟南芥,黑暗条件下转基因植株幼苗对BRZ处理不敏感,提示BnBZL2*可提高转基因植株的BR信号水平.本研究结果表明甘蓝型油菜中存在与拟南芥相似且保守的BR信号通路和调控机制.

油菜素内酯(brassinosteroid,BR)是植物特有的甾体激素,在植物生长发育及逆境应答过程中起重要作用.转录因子BES1/BZR1(BRI1 EMS SUPPRESSOR 1/BRASSINAZOLE RESISTANT 1)是BR信号转导的核心成员,被BR信号激活后,结合到下游靶基因启动子区的E框(CANNTG)或BRRE元件(CGTGT/CG),调节靶基因表达.除介导BR信号,BES1/BZR1还参与脱落酸、赤霉素及光等信号转导途径,协同调控植物的生长发育.最新研究发现,BES1/BZR1还参与调控植物的抗逆性.本文对转录因子BES1/BZR1通过信号转导调控植物生长发育和抗逆性分子机制的新近研究进展进行了综述,以期为相关研究提供参考.

The blue-light receptor cryptochrome 1 (CRY1) primarily mediates blue-light inhibition of hypocotyl elongation in Arabidopsis.However,the underlying mechanisms remain largely elusive.We report here that CRY1 inhibits hypocotyl elongation by repressing brassinosteroid (BR) signaling.A genetic interaction assay reveals the negative regulatory effect of CRY1 on the function of BZR1,a core transcription factor in the BR signaling pathway.We demonstrated that CRY1 interacts with the DNA-binding domain of BZR1 to interfere with the DNA-binding ability of BZR1,and represses its transcriptional activity.Furthermore,we found that CRY1 promotes the phosphorylation of BZR1 and inhibits the nuclear accumulation of BZR1.Interestingly,we discovered that CRY1 interacts with the GSK3-like kinase BIN2 and enhances the interaction of BIN2 and BZR1 in a light-dependent manner.Our findings revealed that CRY1 negatively regulates the function of BZR1 through at least two mechanisms:interfering with the DNA-binding ability of BZR1 and promoting the phosphorylation of BZR1.Therefore,we uncover a novel CRY1-BIN2-BZR1 regulatory module that mediates crosstalk between blue light and BR signaling to coordinate plant growth in Arabidopsis.