光受体UVR8对UV-B响应机制研究进展

来自太阳光谱中的UV-B辐射被认为是一种重要的环境信号,可以被植物感受并诱导植物调整自身生长和发育状态以适应环境。人们对植物中光敏色素、隐花色素和蓝光受体向光素的研究已非常深入,但对植物响应UV-B的机制仅在最近才取得一些突破性进展。这些研究发现,植物中存在着UV-B受体UVR8(UV Resistance Locus 8)。目前认为,UVR8二聚体感应UV-B后瞬间解聚为单体,并与E3泛素连接酶COP1(constitutively photomorphogenic 1)相互作用,从而激活UV-B响应基因的表达。该文从UVR8的发现、UVR8的结构和感受UV-B机制、UVR8二聚体重新形成以及UV-B信号传导与可见光信号传导途径间的差异等方面综述了关于UV-B受体UVR8的最新研究成果。     

甘薯紫外光受体IbUVR8基因克隆及表达特性分析北大核心CSCD

UVR8是植物唯一的UV-B紫外光受体,为深入研究甘薯UVR8的功能,该研究以叶菜型甘薯‘福菜薯23号’为试验材料,采用CODEHOP结合RACE技术,设计简并引物,克隆得到甘薯UVR8全长cDNA序列,并命名为IbUVR 8,利用qRT-PCR分析IbUVR 8在非生物胁迫下的表达特性,并通过原核表达获取IbUVR8蛋白,为IbUVR 8基因在甘薯花青素合成调控作用奠定理论基础。结果表明:(1)成功克隆获得甘薯IbUVR 8基因(NCBI登录号KT749986),该基因全长开放阅读框为1329 bp,共编码了441个氨基酸,相对分子量为47 kD,理论等电点为5.72。(2)序列对比和进化分析结果显示,IbUVR8与番茄、马铃薯UVR8蛋白序列相似性高,进化相对保守。(3)qRT-PCR结果显示,IbUVR 8基因在甘薯中具有组织特异性,表达量为叶片>茎>根;在低温、干旱和NaCl等非生物胁迫下,IbUVR 8基因在3种不同叶色甘薯中均为上调表达;在激素GA 3和重金属Cu 2+胁迫下,IbUVR 8基因在不同甘薯材料的表达趋势差异显著。(4)原核表达获得大小约为80 kD的IbUVR8-GST融合蛋白。研究认为,甘薯IbUVR 8基因受低温、干旱和NaCl等胁迫影响,推测IbUVR 8可能在甘薯抗逆胁迫信号通路中发挥调控作用。     

干旱胁迫下拟南芥中H_2S与ABA信号关系研究

以野生型拟南芥(WT)、硫化氢(H_2S)合成酶缺失型突变体lcd、脱落酸(ABA)合成缺失型突变体aba1实生苗为材料,以0.3 mol·L^-1甘露醇模拟干旱胁迫,研究干旱胁迫对ABA含量、H_2S含量的影响,及其在拟南芥抵抗干旱胁迫中的作用及信号关系。结果显示:干旱胁迫显著提高LCD和ABA1基因相对表达以及H_2S含量,ABA含量;干旱胁迫显著抑制突变体lcd、aba1的种子萌发;干旱胁迫下,外施NaHS促进干旱胁迫下WT、lcd和aba1中內源H_2S的产生及上调LCD、ABA1基因相对表达,而外施ABA提高干旱胁迫下WT、aba1中H_2S含量及LCD、ABA1基因相对表达,但是对lcd中H_2S含量及LCD基因相对表达没有显著影响。研究结果表明,信号分子H_2S和ABA在拟南芥的干旱胁迫响应中发挥一定的作用,且H_2S位于ABA的下游参与调控拟南芥的信号过程。     

铁蛋白DrfE对耐辐射异常球菌抗氧化酶活性的影响

为研究耐辐射异常球菌(Deinococcus radiodurans)中drf E编码的铁蛋白Drf E的功能,通过基因回补试验构建drf E基因的回补菌株(pdrf E∷Δ),对野生型WT、突变株Δdrf E及回补菌株pdrf E∷Δ进行不同浓度H_2O_2和Na Cl胁迫,分别测定野生型WT、突变株Δdrf E和回补菌株pdrf E∷Δ体内Fe2+含量及抗氧化酶类活性。结果显示,drf E基因缺失导致菌株对氧化和盐胁迫敏感,该基因的回补能够恢复菌株对氧化和盐胁迫的抗性。drf E基因缺失导致耐辐射异常球菌体内Fe2+浓度由232μmol/L增加至293μmol/L;80 mmol/L H_2O_2处理30 min后,突变株Δdrf E的CAT活性下降32.74%,SOD下降41.3%。以上结果表明Drf E蛋白可能参与耐辐射异常球菌铁代谢途径,并且在细胞抗氧化体系中发挥重要作用。     

植物UV-B受体及其介导的光信号转导

拟南芥（Arabidopsis thaliana）蛋白UVR8（UV RESISTANCE LOCUS 8）是UV-B特异的光受体,介导UV-B诱导的光形态建成。无UV-B照射时,UVR8以二聚体的形式存在于细胞质和细胞核中。接收到UV-B光信号后,细胞质中的UVR8转移到细胞核中并解聚,之后与E3泛素连接酶COP1（CONSTITUTIVELY PHOTOMORPHOGENIC 1）相互作用,调节一系列重要的UV防御基因的表达。UVR8除了作为UV-B特异的光受体,在细胞中也具有重要作用,协调整个植物体对UV-B的应答。该文重点综述了UVR8蛋白的结构、生理功能及其介导的UV-B光信号转导分子机制等方面的研究进展。     

低温促进毛竹叶片类黄酮合成及相关基因的表达模式分析

类黄酮在植物耐低温胁迫方面发挥着重要作用,为揭示低温对毛竹(Phyllostachys edulis)叶片中类黄酮合成的影响,采用分光光度法测定了不同生长时期和低温胁迫下毛竹幼苗叶片中的类黄酮含量,通过生物信息学方法对毛竹类黄酮早期生物合成关键酶基因进行了鉴定,并用q PCR方法分析了其表达模式。结果表明,随着叶片的生长,类黄酮含量呈现先升高后降低的趋势,而低温下,功能叶片中类黄酮含量则呈现上调趋势,且在8 h时达极显著水平。在毛竹基因组中鉴定了类黄酮早期生物合成3个酶基因家族共29个成员,包括20个查尔酮合酶基因(Pe CHSs)、8个查尔酮异构酶基因(Pe CHIs)和1个黄酮-3-烃化酶基因(Pe F3H1),这些基因的启动子中均含有响应低温及其他非生物胁迫的调控元件。Pe CHSs倾向在根和叶中表达,而PeCHIs为组成型表达。在不同生长时期的叶片中,仅PeCHS1表达与类黄酮的含量变化趋势一致;而低温胁迫下,3个PeCHSs、2个PeCHIs和PeF3H1在功能叶片中呈上调表达,与类黄酮含量变化趋势一致。因此,毛竹可能通过提高类黄酮早期生物合成酶基因的表达量促进类黄酮的合成来...     

拟南芥中H_2S与PLDα1响应干旱胁迫的作用研究

以野生型拟南芥WT、PLDα1合成缺陷突变体pldα1-1以及L-半胱氨酸脱巯基酶(L-cysteine desulfyrase,L-CDes)合成缺陷突变体lcd-4幼苗为材料,以0.3 mol·L~(-1)甘露醇模拟干旱胁迫,研究磷脂酶Dα1(phospholipase Dα1,PLDα1)与气体信号分子硫化氢(hydrogen sulfide,H2S)响应干旱胁迫的作用及可能存在的信号关系。结果显示:干旱胁迫下,野生型拟南芥的H_2S含量、PLD与L/D-CDes活性及其基因相对表达量均发生显著的变化。萌发率实验中,与WT相比,pldα1-1和lcd-4对干旱胁迫更加敏感,外施NaHS可以促进干旱胁迫下WT、pldα1-1以及lcd-4种子萌发及內源H_2S产生,而外施PA能提高干旱胁迫下WT、pldα1-1种子萌发率及H_2S含量,但对lcd-4萌发率及H_2S含量没有显著影响。研究结果表明,信号分子H_2S和PLDα1在拟南芥的干旱胁迫响应中发挥一定的作用,且H_2S可能位于PLDα1的下游参与调控拟南芥种子萌发的信号过程。     

一氧化氮对苹果果实愈伤苯丙烷代谢的影响及生理机制分析北大核心CSCD

以“红星”苹果果实为试材,采用0.5 mmol/L的NO供体硝普钠(SNP)溶液浸泡人工损伤的苹果5 min,考察SNP处理后愈伤期间果实失重率和病情指数,分析伤口处苯丙烷代谢关键酶活性和产物含量,以及H_(2)O_(2)含量和过氧化物酶活性,并探讨其相关生理机制,为苹果果实采后快速愈伤提供方法及理论依据。结果表明:(1)SNP处理显著降低了愈伤期间损伤苹果果实的失重率和扩展青霉(Penicillium expansum)损伤接种果实的病情指数,处理果实的失重率和病情指数于处理第5天时较对照分别显著降低40.2%和31.4%。(2)SNP处理显著提高了果实伤口处苯丙烷代谢关键酶苯丙氨酸解氨酶、肉桂酸-4-羟化酶和肉桂醇脱氢酶的活性,并提高了肉桂酸、咖啡酸、阿魏酸、芥子酸、总酚、类黄酮、p-香豆醇、松柏醇、芥子醇及木质素的含量水平;SNP处理显著提高了果实伤口处的H_(2)O_(2)含量以及POD活性。研究发现,NO可通过激活苹果果实伤口处苯丙烷代谢,提高H_(2)O_(2)含量以及POD活性来促进苹果果实的愈伤。     

增强UV-B辐射和干旱对春小麦光合作用及其生长的影响

在室外盆栽条件下研究了UV-B辐射和土壤干旱对春小麦 '和尚头'生长和光合作用的影响.结果显示:(1)干旱、UV-B辐射、干旱+UV-B(复合)处理均可使叶片类黄酮含量增加,且干旱+UV-B处理增加显著高于其他处理(P<0.05).UV-B辐射和干旱单独处理均能显著降低叶片光合色素含量,但UV-B辐射的副作用大于干旱,复合处理对光合色素的影响介于UV-B和干旱之间.(2)各处理间的光合速率日均值大小次序为:对照>UV-B+干旱>UV-B>干旱;增强UV-B对净光合速率的抑制作用大于干旱,而UV-B+干旱处理的抑制作用较二者单独处理有所减轻.(3)UV-B辐射和干旱单独处理后总生物量比对照减少15%,且抑制作用为:干旱>UV-B>复合处理; UV-B辐射和干旱胁迫不但影响春小麦的生物量,而且影响小穗特征和产量.研究表明,UV-B辐射和干旱之间存在交互作用,说明一种胁迫可以减缓(轻)另外一种胁迫对春小麦的抑制作用.     

UV-B辐射对报春花的生理生化效应

通过室内模拟试验,研究不同强度的UV-B辐射(10μW/cm2和20μW/cm2)对报春花生理代谢的影响,结果表明:(1)增强UV-B辐射下,报春花叶片叶绿素含量降低,且随UV-B辐射时间的延长,降低程度加大;(2)随UV-B辐射强度的增加,叶片质膜透性增加;(3)叶片类黄酮含量随着UV-B辐射强度的增加而增加,在辐射至40 d时,叶片类黄酮含量达到最大值;(4)增强UV-B辐射下,报春花花瓣中花青素含量增加.     

罗布麻和大麻状罗布麻UV-B光受体UVR8基因的鉴定及表达分析

在植物响应紫外线B(ultraviolet-B,UV-B)的过程中,UV-B光受体UVR8(UV Resistance Locus 8)对植物的光形态建成和生长代谢等过程具有重要调控作用。为探究罗布麻属植物UV-B光受体信息,该研究通过罗布麻(Apocynum venetum)和大麻状罗布麻(A. cannabinum)全基因组数据进行UV-B光受体UVR8的筛选与生物信息学分析,同时利用转录组数据分析UV-B胁迫处理下的UVR8基因表达模式。结果表明:(1)罗布麻有6个UVR8基因,大麻状罗布麻有5个UVR8基因,前者分布在1、7、9和11号染色体上,后者分布在1、8和9号染色体上。(2)UVR8蛋白为亲水性稳定蛋白,定位在细胞核,不存在跨膜结构和信号肽,二级结构主要由延伸链、无规则卷曲、α-螺旋和β-转角构成。AvUVR8b和AcUVR8a蛋白三级结构与拟南芥UVR8(AtUVR8)最为类似,并且与小粒咖啡(CaUVR8)和伊德斯种咖啡(CeUVR8)的亲缘关系最近。同时发现罗布麻AvUVR8b和大麻状罗布麻AcUVR8a基因和蛋白结构与AtUVR8基因及蛋白高度相似。(3)当以一定剂量UV-B(17.52 kJ·m^-2·d^-1)处理两种罗布麻植株时,AvUVR8b和AcUVR8a的表达量上调。据此推测在响应UV-B时,AvUVR8b基因在罗布麻中起主要作用,AcUVR8a基因在大麻状罗布麻中起主要作用。(4)顺式作用元件分析结果表明,UVR8的表达受光照、温度、水分、氧气和激素等因素的调控。该研究将为进一步研究罗布麻属UVR8的基因功能奠定基础,同时为解析罗布麻属植物适应UV-B的分子机制提供线索。     

Role of nitric oxide in UV-B-induced activation of PAL and stimulation of flavonoid biosynthesis in Ginkgo biloba callus

The role of nitric oxide (NO) in UV-B-induced secondary metabolite accumulation in Ginkgo biloba callus was investigated. Overall, UV-B irradiation induced multiple biological responses in callus of G. biloba, including increased both NO production and nitric oxide synthase (NOS) activity, and subsequent activation of phenylalanine ammonium lyase (PAL) and synthesis of flavonoids. Application of NO via the donor sodium nitroprusside (SNP) enhanced UV-B-induced PAL activity and increased accumulation of flavonoids in G. biloba callus. Both, the NOS inhibitor l-NAME (N (G)-nitro-l-arginine methyl ester) and the NO scavenger c-PTIO (2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) reduced the production of NO. Moreover, UV-B-induced increase of PAL activity and flavonoid accumulation were suppressed by l-NAME and c-PTIO. These findings suggested a causal relationship between NO release and both PAL activity and flavonoid accumulation under UV-B irradiation. In addition, it also indicated that NO, produced via NOS-like activity in ginkgo callus subjected to UV-B irradiation, might act as an essential signaling molecule for triggering the activation of PAL and synthesis of flavonoids. Additionally, a guanylyl cyclase inhibitor 6-anilino-5,8-quinolinequinone (LY-83583) prevented both UV-B- and SNP-induced enhancement of PAL activation and flavonoid biosynthesis thus suggesting that the NO function was mediated by cyclic guanosine 5’-monophosphate. However, these effects of c-PTIO, l-NAME, and LY-83583 were partial, thus suggesting that there were NO-independent pathways in UV-B signaling networks. Gangping Hao and Xihua Du are contributed equally to this article.     

UV-B预处理诱导拟南芥耐旱性的提高

为了解UV-B提高拟南芥(Arabidopsis thaliana)耐旱性的生理机制,将2周龄的野生型拟南芥(WT)和sto突变体幼苗用不同剂量UV-B预处理1周,再用30%PEG模拟干旱处理24 h,对植株的表型进行统计,并测定类黄酮、脯氨酸和MDA含量。结果表明,低剂量UV-B预处理能够提高拟南芥的耐旱性,植株的类黄酮与脯氨酸含量分别提高了20%～40%和50%～65%,细胞膜受损程度降低,从而提高了保水性。低剂量UV-B提高拟南芥耐旱性的效应在sto突变体中消失,证明这种效应在分子机制上可能与STO蛋白相关。     

基于转录组和代谢组分析马齿苋根茎叶中类黄酮代谢

为获取马齿苋(Portulaca oleracea)类黄酮相关成分及其合成酶基因信息,该实验以马齿苋根、茎和叶为材料,进行代谢组学和转录组学联合分析,并从中选取6个差异表达基因进行qRT-PCR验证分析.结果显示:(1)代谢组分析发现,在马齿苋根、茎和叶中共获得32个类黄酮相关化合物,包括3个异黄酮、8个黄酮醇、11个...     

How plants protect themselves from ultraviolet-B radiation stress

Ultraviolet-B (UV-B) radiation has a wavelength range of 280–315 nm. Plants perceive UV-B as an environmental signal and a potential abiotic stress factor that affects development and acclimation. UV-B regulates photomorphogenesis including hypocotyl elongation inhibition, cotyledon expansion, and flavonoid accumulation, but high intensity UV-B can also harm plants by damaging DNA, triggering accumulation of reactive oxygen species, and impairing photosynthesis. Plants have evolved “sunscreen” flavonoids that accumulate under UV-B stress to prevent or limit damage. The UV-B receptor UV RESISTANCE LOCUS 8 (UVR8) plays a critical role in promoting flavonoid biosynthesis to enhance UV-B stress tolerance. Recent studies have clarified several UVR8-mediated and UVR8-independent pathways that regulate UV-B stress tolerance. Here, we review these additions to our understanding of the molecular pathways involved in UV-B stress tolerance, highlighting the important roles of ELONGATED HYPOCOTYL 5, BRI1-EMS-SUPPRESSOR1, MYB DOMAIN PROTEIN 13, MAP KINASE PHOSPHATASE 1, and ATM- and RAD3-RELATED. We also summarize the known interactions with visible light receptors and the contribution of melatonin to UV-B stress responses. Finally, we update a working model of the UV-B stress tolerance pathway.

Recent findings that update our understanding of the molecular pathway for ultraviolet-B radiation stress responses in plants are summarized.     

Isolate-specific effects of ultraviolet radiation on photosynthesis,growth and mycosporine-like amino acids in the microbial mat-forming cyanobacterium <Emphasis Type="Italic">Microcoleus </Emphasis><Emphasis Type="Italic">chthonoplastes</Emphasis>

Microcoleus chthonoplastes constitutes one of the dominant microorganisms in intertidal microbial mat communities. In the laboratory, the effects of repeated daily exposure to ultraviolet radiation (16:8 light:dark cycle) was investigated in unicyanobacterial cultures isolated from three different localities (Baltic Sea = WW6; North Sea = STO and Brittany = BRE). Photosynthesis and growth were measured in time series (12–15 days) while UV-absorbing mycosporine-like amino acids (MAAs) and cellular integrity were determined after 12 and 3 days exposure to three radiation treatments [PAR (22 μmol photon m⁻² s⁻¹) = P; PAR + UV-A (8 W m⁻²) = PA; PAR + UV-A + UV-B (0.4 W m⁻²) = PAB]. Isolate-specific responses to UVR were observed. The proximate response to radiation stress after 1-day treatment showed that isolate WW6 was the most sensitive to UVR. However, repeated exposure to radiation stress indicated that photosynthetic efficiency (F _v/F _m) of WW6 acclimated to UVR. Conversely, although photosynthesis in STO exhibited lower reduction in F _v/F _m during the first day, the values declined over time. The BRE isolate was the most tolerant to radiation stress with the lowest reduction in F _v/F _m sustained over time. While photosynthetic efficiencies of different isolates were able to acclimate to UVR, growth did not. The discrepancy seems to be due to the higher cell density used for photosynthesis compared to the growth measurement. Apparently, the cell density used for photosynthesis was not high enough to offer self-shading protection because cellular damage was also observed in those filaments under UVR. Most likely, the UVR acclimation of photosynthesis reflects predominantly the performance of the surviving cells within the filaments. Different strategies were observed in MAAs synthesis. Total MAAs content in WW6 was not significantly different between all the radiation treatments. In contrast, the additional fluence of UV-A and UV-B significantly increased MAAs synthesis and accumulation in STO while only UV-B fluence significantly increased MAAs content in BRE. Regardless of the dynamic photosynthetic recovery process and potential UV-protective functions of MAAs, cellular investigation showed that UV-B significantly contributed to an increased cell mortality in single filaments. In their natural mat habitat, M. chthonoplastes benefits from closely associated cyanobacteria which are highly UVR-tolerant due to the production of the extracellular UV-sunscreen scytonemin.     

不同光质对红花檵木愈伤组织生长及黄酮类物质含量的影响

该试验以红花檵木叶片诱导的愈伤组织为试验材料,以黑暗(CK)为对照,分别进行白光(W)、红光(R)、蓝光(B)、蓝紫光(BP)、蓝光+UV-A(B+UV A)和UV-A处理15d和30 d,通过对愈伤组织的生长、生理指标、花色素苷和总黄酮含量的比较分析,探讨光质对红花檵木愈伤组织生长和黄酮类物质含量的影响.结果 显示:...     

中国沙棘HrANR基因及黄酮类累积与抗旱的关系

花青素还原酶(anthocyanidin reductase, ANR)是合成黄酮类物质的关键酶之一,为明确其编码基因结构及干旱胁迫下的表达模式和黄酮类物质含量及二者之间的相关性,该文从中国沙棘转录组数据中筛选获得1个ANR基因,命名为HrANR基因。采用生物信息学软件对基因序列及编码蛋白进行分析,并对不同胁迫下各组织中HrANR基因的表达量和叶中黄酮类化合物含量进行相关性分析。结果表明:(1)中国沙棘HrANR基因ORF为1 017 bp,编码338个氨基酸,为稳定的亲水性蛋白,其ANR同源蛋白具有明显的科属特性。(2)干旱胁迫下HrANR基因在中国沙棘根、茎、叶中均有表达,但表达趋势不同,其中在根中的表达呈先升高后降低再升高的趋势,在茎中呈持续下降的趋势,在叶中呈先升高后持续降低的趋势。(3)通过芦丁标准曲线获得不同胁迫程度下中国沙棘叶内黄酮类的含量,表明黄酮类含量呈先持续上升,随后略有下降,复水后上升至最高点的变化趋势,表明干旱胁迫初期叶黄酮类含量与干旱胁迫呈正相关,在严重胁迫下黄酮类含量与胁迫呈负相关。(4)叶和茎的HrANR基因表达量与黄酮类含量呈负相关(P_叶=-0.751,P_茎=-0.934),根中呈正相关(P_根=0.444)。综上表明,中国沙棘HrANR基因的表达及黄酮类含量变化与其抗旱性密切相关,其结果为中国沙棘抗旱机制的阐明提供了依据。     

过表达OsCatC基因水稻的获得及其耐盐性机理分析

过氧化氢酶C (Catalase C,CatC)作为重要的抗氧化酶,在水稻发育和胁迫响应方面起重要作用。为了探究CatC在盐胁迫响应中的功能及其作用机制,该研究构建了OsCatC过表达转基因水稻,并比较了其耐盐性和相关抗逆生理指标的变化。结果表明:(1)成功构建过量表达载体pCUbi1390-OsCatC-Flag,并经农杆菌介导的愈伤组织转化获得了30个独立转基因株系(T₀),Western blot鉴定T₁代幼苗共获得2个OsCatC过表达株系(OE-10、OE-18);qRT-PCR分析发现,OE-10和OE-18株系的OsCatC转录水平显著高于野生型(WT),证明OsCatC基因已成功过表达于转基因株系(OE-10、OE-18)中,且能正常翻译为融合蛋白CatC-Flag。(2)正常水培条件下,OE-10和OE-18与WT的水稻幼苗长势无明显差异,200 mmol·L^-1 NaCl处理7 d后再恢复水培10 d时,OE-10和OE-18幼苗的存活率为20%～25%,而WT幼苗绝大部分则干枯死亡,存活率仅为5%左...     

Variation in the quality and quantity of flavonoids in the leaves of coastal and inland Campanula punctata

Ultraviolet-B radiation is known as a noxious factor that destroys every life form. Plants that occupy the coastal area are assumed to be adaptive to UV-B as well as the other major stresses. The objective of this study was to clarify and compare (1) the flavonoid compositions of coastal and inland populations of Campanula punctata, and (2) UV-B effects on flavonoid content in plants originating from different habitats under uniform (i.e. experimental) and natural conditions. Flavonoid compositions of coastal and inland populations were shown to be identical. The UV-B exclusion experiment revealed two tendencies that were commonly observed in both coastal and inland populations: (1) the flavonoid accumulation decreased with an increase in degree of UV-B exclusion, and (2) the quantity of phenolic acids conversely became maximum under complete UV-B exclusion. Under the natural habitat conditions, significantly high accumulation of flavonoids were detected in two coastal populations even though no significant difference was found between the two other coastal populations and two inland populations. Weak correlations between UV-B intensity and flavonoid accumulation under the natural habitat conditions suggest that various micro-environmental factors may influence the production of flavonoids, and that the plants may acquire adaptive traits other than increasing flavonoids in order to inhabit the coastal environment.