The COI1 and DFR Genes are Essential for Regulation of Jasmonate-Induced Anthocyanin Accumulation in Arabidopsis

Jasmonates(JAs)are a class of plant hormones that play important roles in the regulation of plant development and plantdefense.It has been shown that Arabidopsis plants produce much higher levels of anthocyanins when treated exogenouslywith methyl jasmonate(MeJA).However,a molecular link between the JA response and anthocyanin production hasnot been determined.The CORONATINE INSENTITIVE1(COI1)gene is a key player in the regulation of many JA-relatedresponses.In the present study,we demonstrate that the COI1 gene is also required for the JA-induced accumulation ofanthocyanins in Arabidopsis.Furthermore,the MeJA-inducible expression of DIHYDROFLAVONOL REDUCTASE(DFR),anessential component in the anthocyanin biosynthesis pathway,was completely eliminated in the coil mutant.Jasmonate-induced anthocyanin accumulation was found to be independent of auxin signaling.The present results indicate that theexpression of both COI1 and DFR genes is required for the regulation of JA-induced anthocyanin accumulation and thatDFR may be a key downstream regulator for this process.     

ASK1 physically interacts with COI1 and is required for male fertility in Arabidopsis

Jasmonates are a new class of plant hormones that play important roles in plant development and plant defense. The COI1 gene was previously shown to be required for jasmonate-regulated plant fertility and defense. We demonstrated for the first time that COI1 interacts with the Arabidopsis SKP1-LIKE1 (ASK1) to form a complex that is required for jasmonate action in planta. Functional analysis by antisense strategy showed that ASK1 is involved in male fertility.     

Anthocyanin Accumulation Mediated by Blue Light and Cytokinin in Arabidopsis Seedlings

It has been reported that pigmentation In plants Is stimulated by light and cytoklnln （CTK）; however, the signaling pathways and the relationship between light and CTK Involved In the regulation of anthocyanln accumulation remain to be elucidated. We Investigated （i） the role of blue light （BL） and CTK In anthocyanln accumulation ; and （ii） the relationship between BL and CTK In wild type （WT） and by4 mutants of Arabidopsis thaiiana. Two-d-old seedlings grown on medium with or without klnetln （KT） or zeatln （ZT） In darkness were Irradiated using BL at different fluence rates for 3 d before the anthocyanln content was determined using a spectrophotometrlc method. Anthocyanln accumulation was strongly Induced by BL In WT seedlings but not In hy4 seedlings, which demonstrated that CRY1 Is the main photoreceptor for BL. Both KT and ZT enhanced the response of the WT seedlings to BL In a dose-dependent manner, whereas they were not sufficient to promote anthocyanln eccumulatlon In darkness. In addition, data from experiments using the hy4 mutant showed that the CTK effect of BL was also CRYl-dependent. The results from experiments with three different treatment programs showed that the relationship between BL and KT In anthocyanln accumulation of Arabidopsis seedlings seems neither muItlpllcatlve nor additive coactlon, but rather Interaction. BL Is necessary for anthocyanln accumulation, and KT might be Involved In the BL signaling pathway.     

COI1 links jasmonate signalling and fertility to the SCF ubiquitin-ligase complex in Arabidopsis

Jasmonates (JAs) regulate Arabidopsis thaliana wound and defence responses, pollen development, and stress-related growth inhibition. Significantly, each of these responses requires COI1, an F-box protein. Other F-box proteins interact with SKP1 and cullin proteins to form SCF complexes that selectively recruit regulatory proteins targeted for ubiquitination. To determine whether COI1 also functions in an SCF complex, we have characterized Arabidopsis proteins that bind to COI1. An Arabidopsis cDNA expression library was screened in yeast for clones that produce proteins which can bind to COI1. We recovered two SKP1 homologues and a histone deacetylase. The Arabidopsis F-box protein TIR1 interacted with SKP1 proteins, but not with the histone deacetylase. Mutant COI1 proteins revealed that the F-box is required for interaction with SKP1s, but that sequences in leucine-rich repeat domains are required for interaction with the histone deacetylase. Epitope-tagged COI1 was introduced into Arabidopsis plants and cell cultures. Co-immunoprecipitation experiments confirmed the interaction in planta of COI1 with SKP1-like proteins and histone deacetylase, and also indicated that COI1 interacted with cullin. These results suggest that COI1 forms an SCFCOI1 complex in vivo. COI1 is therefore expected to form a functional E3-type ubiquitin ligase in plants and to regulate expression of jasmonate responsive genes, possibly by targeted ubiquitination of a histone deacetylase.     

THF1 mutations lead to increased basal and wound-induced levels of oxylipins that stimulate anthocyanin biosynthesis via COI1 signaling in Arabidopsis

Mutants defective in chloroplast development or photosynthesis are liable to accumulate higher levels of anthocyanin in photo-oxidative stress. However, regulatory mechanisms of anthocyanin biosynthesi...     

Another JA/COI1-independent role of OPDA detected in tomato embryo development

Jasmonates (JAs) are ubiquitously occurring signaling compounds in plants formed in response to biotic and abiotic stress as well as in development. (+)-7-iso-jasmonoyl isoleucine, the bioactive JA, is involved in most JA-dependent processes mediated by the F-box protein COI1 in a proteasome-dependent manner. However, there is an increasing number of examples, where the precursor of JA biosynthesis, cis-(+)-12-oxophytodienoic acid (OPDA) is active in a JA/COI1-independent manner. Here, we discuss those OPDA-dependent processes, thereby giving emphasis on tomato embryo development. Recent data on seed coat-generated OPDA and its role in embryo development is discussed based on biochemical and genetic evidences.     

基于转录组测序的细风轮花青素合成途径及关键酶基因分析

为进一步理解细风轮花青素合成途径,本研究利用华大基因BGISEQ-500平台对细风轮中的根、茎、叶、花4个组织进行了转录组测序,从头组装后得到128 856个Unigene。KEGG通路表明有40个Unigene编码了细风轮的花青素生物合成途径中6个关键酶。我们对其中的关键酶DFR（二氢黄酮醇还原酶）进行同源比对和空间结构模拟,结果显示DFR序列和结构均具有良好的保守性,且具有高度保守的NAD⁺结合位点,其二级结构主要由α螺旋和β折叠组成,在空间上α螺旋包裹着β折叠,形成“夹心饼干”样结构。     

COI1参与茉莉酸调控拟南芥吲哚族芥子油苷生物合成过程

芥子油苷是一类具有防御作用的植物次生代谢产物,外源激素茉莉酸对吲哚族芥子油苷的合成具有强烈的诱导作用,但茉莉酸调控吲哚族芥子油苷生物合成的分子机制并不清楚。以模式植物拟南芥(Arabidopsis thaliana)的野生型和coi1-22、coi1-23两种突变体为研究材料,通过茉莉酸甲酯(MeJA)处理,比较了拟南芥野生型和coi1突变体植株吲哚族芥子油苷含量、吲哚族芥子油苷合成前体色氨酸的生物合成基因(ASA1、TSA1和TSB1)、吲哚族芥子油苷生物合成基因(CYP79B2、CYP79B3和CYP83B1)及调控基因(MYB34和MYB51)的表达对MeJA的响应差异,由此确定茉莉酸信号通过COI1蛋白调控吲哚族芥子油苷生物合成,即茉莉酸信号通过信号开关COI1蛋白作用于转录因子MYB34和MYB51,进而调控吲哚族芥子油苷合成基因CYP79B2、CYP79B3、CYP83B1和前体色氨酸的合成基因ASA1、TSA1、TSB1。并且推断,COI1功能缺失后,茉莉酸信号可能通过其他未知调控因子或调控途径激活MYB34转录因子从而调控下游基因表达。     

ASK1 physically interacts with COI1 and is required for male fertility in<Emphasis Type="Italic">Arabidopsis</Emphasis>

Jasmonates are a new class of plant hormones that play important roles in plant development and plant defense. TheCOI1 gene was previously shown to be required for jasmonate-regulated plant fertility and defense. We demonstrated for the first time that COI1 interacts with theArabidopsis SKP1-LIKE1 (ASK1) to form a complex that is required for jasmonate action inplanta. Functional analysis by antisense strategy showed thatASK1 is involved in male fertility.     

CONSTANS-LIKE 7过量表达降低白光和蓝光下拟南芥幼苗花青素及叶绿素的含量

以拟南芥野生型(WT)、突变体col7、以及COL7过量表达转基因株系COL7-OX-10和COL7-OX-11为实验材料,观察比较了白光、红光以及蓝光下,生长在MS培养基上的幼苗表型,以及蓝光下生长在0、100 mmol/LNaCl MS培养基上的幼苗表型。结果发现,过量表达株系幼苗在白光和蓝光下出现黄化现象,并且NaCl处理导致蓝光下幼苗黄化现象更加严重。检测幼苗的花青素及叶绿素的含量,发现白光和蓝光下,过量表达株系幼苗中花青素和叶绿素的含量明显降低,其中蓝光下生长在含100 mmol/L NaCl的MS培养基上幼苗的花青素和叶绿素含量下降尤为明显,表明COL7可能参与调控花青素和叶绿素的合成,并依赖于蓝光。     

蓝粒小麦花青素生物合成途径中的二氢黄酮醇4-还原酶基因的分子克隆

蓝色色素在蓝粒小麦种子糊粉层中的生物合成途径的分子生物学机制至今仍不清楚。应用RT—PCR和RACE方法从蓝粒小麦正在发育的种子中克隆到一个编码二氢黄酮醇4-还原酶的基因(DFR)。推测其为花青素生物合成途径中的一个关键基因,且与蓝粒小麦中蓝色色素形成密切相关;其开放阅读框编码一个包含354个氨基酸残基的多肽,与一些从其他植物中已克隆到的DFR有很高的同源性：大麦(94％)、水稻(83％)、玉米(84％)。从长穗偃麦草(2n=70)、蓝粒小麦、浅蓝粒小麦自交产生的白粒后代小麦以及中国春的基因组中分别分离到一个全长DFR序列。经聚类分析表明DFR cDNA核甘酸序列与从中国春基因组中克隆的DFR具有100％的同源性,且与长穗偃麦草、蓝粒小麦、白粒小麦基因组中分离的DFR均有很高的同源性。4个DFR基因组DNA均含有3个内含子,且它们之间的差异主要在内含子区,表明该基因在进化上很保守。经Southern杂交分析,DFR小麦中至少有3-5个拷贝,不同小麦材料间未见明显差异,但与长穗偃麦草有明显差异,属于一个DFR超基因家族。Northern分析表明该DFR在蓝粒和白粒种子的不同发育时期的表达存在明显差异,都在开花后大约18d表达最强,在同一时期的蓝白种子中,DFR蓝粒种子中的表达量高于白粒。DFR转录本在小麦和长穗偃麦草的幼叶中积累多,但在芽鞘中的表达显著低于幼叶中;在小麦的根和长穗偃麦草的发育种子中均未检测到DFR的表达。推测蓝粒小麦中可能存在调控DFR在蓝粒小麦中表达的调控基因,类似于玉米花青素合成途径中的调节基因。     

蓝粒小麦花青素生物合成途径中的二氢黄酮醇4-还原酶基因的分子克隆

蓝色色素在蓝粒小麦种子糊粉层中的生物合成途径的分子生物学机制至今仍不清楚.应用RT-PCR和RACE方法从蓝粒小麦正在发育的种子中克隆到一个编码二氢黄酮醇4-还原酶的基因(DFR).推测其为花青素生物合成途径中的一个关键基因,且与蓝粒小麦中蓝色色素形成密切相关;其开放阅读框编码一个包含354个氨基酸残基的多肽,与一些从其他植物中已克隆到的DFR有很高的同源性:大麦(94%)、水稻(83%)、玉米(84%).从长穗偃麦草(2n=70)、蓝粒小麦、浅蓝粒小麦自交产生的白粒后代小麦以及中国春的基因组中分别分离到一个全长DFR序列.经聚类分析表明DFR cDNA核甘酸序列与从中国春基因组中克隆的DFR具有100%的同源性,且与长穗偃麦草、蓝粒小麦、白粒小麦基因组中分离的DFR均有很高的同源性.4个DFR基因组DNA均含有3个内含子,且它们之间的差异主要在内含子区,表明该基因在进化上很保守.经Southern杂交分析,DFR在小麦中至少有3～5个拷贝,不同小麦材料间未见明显差异,但与长穗偃麦草有明显差异,属于一个DFR超基因家族.Northern分析表明该DFR在蓝粒和白粒种子的不同发育时期的表达存在明显差异,都在开花后大约18 d表达最强,在同一时期的蓝白种子中,DFR在蓝粒种子中的表达量高于白粒.DFR转录本在小麦和长穗偃麦草的幼叶中积累多,但在芽鞘中的表达显著低于幼叶中;在小麦的根和长穗偃麦草的发育种子中均未检测到DFR的表达.推测蓝粒小麦中可能存在调控DFR在蓝粒小麦中表达的调控基因,类似于玉米花青素合成途径中的调节基因.     

ABA信号通路对葡萄果皮花青苷生物合成的调控机制研究

以'红巴拉多'葡萄为试验材料,在转色前期(约花后6周)用300 mg/L的ABA对果穗进行处理,以清水处理为对照;测定不同发育时期葡萄果实的单果重、可滴定酸、可溶性固性物等生理指标,同时测定果皮中总花青苷及ABA含量;检测不同发育时期果皮中ABA信号通路和花青苷生物合成相关基因表达量,克隆6个与花青苷生物合成相关基因的...     

F-box蛋白COI1稳定性调控机制

拟南芥F-box蛋白COI1(Coronatine insensitive 1)与ASK1(Arabidopsis serine/Threonine kinase 1)蛋白及CUL1(CULLIN1)蛋白等结合形成SCFCOI1泛素连接酶复合体.COI1感知茉莉素信号、进而调控植物一系列的防御反应和生长发育过程.虽然多种作物的COI1同源蛋白已经被相继鉴定,但是其自身蛋白水平的调控机制仍然未知.本文重点研究了蔬菜作物番茄(Solanum lycopersicum)和经济作物烟草(Nicotiana attenuata)中COI1蛋白稳定性的调控机制.结果证明,这两种作物的COI1蛋白通过与ASK1的相互作用而得到稳定,表明形成SCFCOI1复合体可能有助于COI1蛋白的稳定.同时,26S蛋白酶体抑制剂能够明显抑制COI1的降解,说明泛素-蛋白酶体途径参与了其降解过程.这些结果证明在这两个不同物种中,两条互相拮抗的途径共同发挥作用,平衡并稳定COI1蛋白在细胞内的恰当丰度.该研究为深入研究不同作物的茉莉素信号转导调控机制奠定了良好的基础.     

BEN1, a gene encoding a dihydroflavonol 4-reductase (DFR)-like protein, regulates the levels of brassinosteroids in Arabidopsis thaliana

The ben1-1D (bri1-5 enhanced 1-1dominant) mutant was identified via an activation-tagging screen for bri1-5 extragenic modifiers. bri1-5 is a weak mutant allele of the brassinosteroid receptor gene, BRI1. Overexpression of BEN1 greatly enhances the defective phenotypes of bri1-5 plants. Removal of BEN1 by gene disruption in a Col-0 wild-type background, on the other hand, promotes the elongation of organs. Because BEN1 encodes a novel protein homologous to dihydroflavonol 4-reductase (DFR) and anthocyanidin reductase (BAN), BEN1 is probably involved in a brassinosteroid metabolic pathway. Analyses of brassinosteroid profiles demonstrated that BEN1 is indeed responsible for regulating the levels of several brassinosteroids, including typhasterol, castasterone and brassinolide. In vivo feeding and in vitro biochemical assays suggest that BEN1 is probably involved in a new mechanism to regulate brassinosteroid levels. These results provide additional insight into the regulatory mechanisms of bioactive brassinosteroids.