Isolation and Identification of Submergence-induced Genes in Maize (Zea mays) Seedlings by Suppression Subtractive Hybridization

To investigate the expression profile of maize genes induced by submergence, a subtracted cDNA library of maize seedling roots was constructed using suppression subtractive hybridization (SSH). The cDNA of maize seedling roots treated with submergence (ST) was used as tester and what from untreated roots (UT) as driver. Products of the secondary PCR from the forward subtraction were cloned into T/A vector and transferred into Escherichia coli strain JM10B by electroporation. Four hundred and eight randomly chosen transformants carrying cDNA fragments were screened with PCR-Select Deferential Screening Kit. One hundred and eighty-four cDNA clones were identified as, submergence specifically induced or highly expressed. After sequencing and removing redundant cDNAs, we got 95 submergence-induced cDNA clones. Of the 95 cDNA clones, 68 contain the regions with 60%-90% identity to their homolog in GenBank, 21 are expected to be novel genes, only 6 correspond to the published maize sequences.

Identification of Phosphorus Starvation Inducible Genes in Rice by Suppression Subtractive Hybridization

Phosphorus is one of the three essential macroelements for plant growth. Plants respond to phosphorus starvation through adaptive mechanisms involved in morphological, biochemical and molecular changes. To investigate the molecular background of the adaptive mechanisms, the suppression subtractive hybridization (SSH) method was used to construct a rice phosphorus-starvation ( Pi-starvation) induced cDNA library. Through screening of the cDNA library and sequencing of the enriched cDNAs, 18 known genes and 47 novel genes were identified. The known genes are involved in different metabolic processes, including phosphate uptake and transport, signal transduction, protein synthesis and degradation, carbon metabolism and stress response. Northern analysis was performed to detect the expression patterns of some known genes and novel genes under different phosphorus levels. Different expression patterns of the selected genes were identified, which suggests that genes involved in different pathways may have different responses to Pi-starvation.

Isolating Soil Drought-Induced Genes from Maize Seedling Leaves Through Suppression Subtractive Hybridization

In this study, a forward cDNA library was constructed by suppression subtractive hybridization using seedling leaves of CN165, a drought-tolerant maize inbred line. In the suppression subtractive hybridization （SSH） library, 672 positive clones were picked up randomly. After polymerase chain reaction （PCR） of each clone, all the single clones were sequenced. Totally 598 available sequences were obtained. After cluster analysis of the EST sequences, 80 uniESTs were obtained, among which 57 uniESTs were contigs and 23 uniESTs were singlets. The results of BLASTN showed that all the uniESTs had homologous sequences in the nr database. The BLASTX results indicated that 68 uniESTs had significant protein homology, 8 uniESTs with homology of unknown proteins and putative proteins, and 4 uniESTs without protein homology. Those drought stress-induced genes were involved in many metabolism pathways to regulate plant growth and development under drought stress.

Construction of Two Suppression Subtractive Hybridization Libraries and Identification of Salt-Induced Genes in Soybean

Soybean is planted worldwide and its productivity is significantly hampered by salinity. Development of salt tolerant cultivars is necessary for promoting soybean production. Despite wealth of information generated on salt tolerance mechanism, its basics still remain elusive. A continued effort is needed to understand the salt tolerance mechanism in soybean using suitable molecular tools. To better understand the molecular basis of the responses of soybean to salt stress and to get an enrichment of critical salt stress responsive genes in soybean, suppression subtractive hybridization libraries （SSH） are constructed for the root tissue of two cultivated soybean genotypes, one was tolerant and the other was sensitive to salt stress. To compare the responses of plants in salt treatment and non-treatment, SSH1 was constructed for the salt-tolerant cultivar Wenfeng 7 and SSH2 was constructed for the salt-sensitive cultivar Union. From the two SSH cDNA libraries, a total of 379 high quality ESTs were obtained. These ESTs were then annotated by performing sequence similarity searches against the NCBI nr （National Center for Biotechnology Information protein non-redundant） database using the BLASTX program. Sixty-three genes from SSH1 and 49 genes from SSH2 could be assigned putative function. On the other hand, 25 ESTs of SSH1 which may be not the salt tolerance-related genes were removed by comparing and analyzing the ESTs from the two S SH libraries, which increased the proportion of the genes related to salt tolerance in S SH 1. These results suggested that the novel way could realize low background of SSH and high level enrichment of target cDNAs to some extent.

Identification of Differentially Expressed Genes in the Salivary Gand of Rhipicephalus haemaphysaloides by the Suppression Subtractive Hybridization Approach

For the purpose of screening and analyzing the differentially expressed genes from the salivary gland of Rhipicephalus haemaphysaloides, two salivary gland-subtracted cDNA libraries of partially fed female ticks and fed male ticks were constructed using suppression subtractive hybridization （SSH）. A total of 247 female expression sequence tags （ESTs） and 168 male ESTs were obtained from the two SSH cDNA libraries. It is predicted that 25 female ESTs and 44 female ESTs contain the 5＂ and 3＂ ends, respectively, and that 53 male ESTs and 74 male ESTs contain the 5＂ and 3＂ ends, respectively. To identify the subtraction rate of the two SSH cDNA libraries, the RT-PCR method was used to test 24 female ESTs and 21 male ESTs selected randomly but not repeatedly. The results showed that there were 13 upregulated or differentially expressed genes in the partially fed salivary gland of the female R. haemaphysaloides and that the differentially expressed rate was 54%. In addition, they indicated that there were 9 upregulated or differently expressed genes in the fed salivary gland of the male R. haemaphysaloides and that the differentially expressed rate was 43%. Putative translations of 141 （57%） female ESTs and 125 （74%） male ESTs had similarity to GenBank sequences, and 32 （23%） female ESTs and 29 （23%） male ESTs exhibited similarity to tick proteins, which showed that most of the proteins in the libraries were mainly related to the feeding blood physiology of the ticks.

Construction and Analysis of Suppression Subtractive cDNA Library from Fertile Disk Floret Buds of Zinnia elegans

In order to isolate genes related to anther development and understand molecular basis of male sterility,cDNA library of Zinnia elegans was constructed using suppression subtractive hybridization（SSH） approach.672 different expressed clones were selected from the fertile disk floret buds.PCR results showed that cDNA inserts were ranged from 100 to 750 bp.303 positive clones screened by dot-blot hybridization were sequenced.273 out of 303 sequenced clones produced readable sequences;these sequences represent 87 non-repetitive sequences.The homology alignment showed that 76 expressed sequence tags（ESTs） had functional annotations in GenBank,the other 11 ESTs without any homology to the known gene.In addition,87 ESTs were divided into 17 groups according to MIPS of Arabidopsis thaliana database.Sequence data from the cDNA library have been deposited with the GenBank under the accession numbers GT067016-GT067085.As an important result in this study,7 genes related to anther development were isolated.Results from semi-quantitative RT-PCR showed 6 genes were expressed only in disk florets of fertile plants compared with that of male sterile plants.These ESTs obtained provide important clues for further isolation and identification of fertility-related genes in Z.elegans.

干旱胁迫下棉花SSH文库构建及其抗旱相关基因分析

以耐旱自交系邯郸177为材料,利用抑制性差减杂交技术(SSH),构建棉花苗期叶片的正向差减文库。挑取300个阳性克隆进行PCR验证,并对验证后的单克隆进行测序和分析,共获得284个有效序列。聚类后得到202条uniESTs序列,其中174条singlets,28条contigs。经过BlastN分析,156个unigene可以在GenBank中找到同源序列,46个unigene未能找到同源匹配。经BlastX分析,40个unigene与未知功能蛋白或假定蛋白有较高相似性,116条unigene与已知功能蛋白有较高同源性。用KOBAS系统将33个unigene定位到55个Pathways中,其中P值小于0.5的Pathway有23条。初步分析发现,丙酮酸盐代谢(pyruvate metabolism)途径、乙醛酸和二羧酸代谢(glyoxylate and dicarboxylate metabolism)途径与棉花抗旱相关性较大。这些unigene基因涉及信号传导、能量代谢、蛋白质代谢、核酸代谢、光合作用及膜运输等代谢过程。发现了苹果酸合成酶基因(Ms1,001_B03;Ms2,003_E04)、苹果酸脱氢酶基因(Md1,001_C12;Md2,002_F01);NAC(001_C08)、锌指蛋白(zfp,003_C06)、BZR1/BES1(003_G04)等转录调节因子,以及翻译控制肿瘤蛋白基因(TCTP,002_C04)等耐旱相关基因。

干旱胁迫下柠条锦鸡儿叶片SSH文库构建及CkWRKY1基因克隆

为研究柠条锦鸡儿抗旱的分子机制,挖掘干旱响应相关基因,成功构建干旱胁迫下柠条锦鸡儿叶片的抑制性差减杂交(SSH)文库,获得1286条高质量的EST序列,平均长度475bp,拼接得到Unigenes645条。对这些Unigenes进行Blast比对注释后发现很多抗旱相关基因,例如LEA蛋白、DHN蛋白编码基因,MYB、bZIP、WRKY、NAC和bHLH转录因子等。通过RACE技术克隆其中1个WRKY转录因子的cDNA全长,命名为CkWRKY1,GenBank登录号为JX987095。CkWRKY1编码330个氨基酸的蛋白质,氨基酸序列中有1个"WRKYGQK"的WRKY转录因子家族保守序列,属于第Ⅱ类WRKY转录因子。利用实时荧光定量PCR技术检测发现,CkWRKY1基因在干旱处理后mRNA的表达水平明显上升,预示该转录因子可能与柠条锦鸡儿抗旱的分子机制相关。

黏类小麦育性相关基因SSH文库的构建

为了深入研究黏类小麦雄性不育的分子遗传机制,利用抑制差减杂交技术构建了黏类小麦育性相关基因的cDNA文库。文库质量检测表明,差减杂交效率较高,质量较好。在不育和可育cDNA文库中随机挑选120个阳性克隆进行测序,获得100余条高质量的表达序列标签(EST)。对序列进行BLAST比对及功能注释,比较了不育和可育cDNA文库的基因表达谱,发现在可育cDNA文库中参与能量代谢的基因出现频率较高,在不育cDNA文库中检测到了与花发育调控相关的MADS-box转录因子、细胞凋亡相关的泛素结合酶及阻遏淀粉合成的腺苷二磷酸葡萄糖磷酸化酶等相关基因。这些基因很可能与育性相关。

辣椒Me3基因介导抗根结线虫相关基因的SSH分析

以辣椒(Capsicum annuum L.)双单倍体HDA149为试验材料,接种南方根结线虫(Meloido-gyne incognita)12、24、36h的根尖材料作为测验方(Tester),相应的未接种根尖材料作为驱动方(Driv-er),构建一个南方根结线虫诱导Me3基因表达早期的抑制消减杂交cDNA文库,通过高密度点阵膜杂交差异筛选,获得了309条表达序列标签(EST)。通过测序,除去重复序列共得到259条EST序列,在Gen-Bank上进行BLAST分析,30个EST片段未发现同源性基因,229个为具有同源性的已知基因,其中71个为功能未知的基因。在显微观察和抗性相关EST表达谱分析的基础上,推测在Me3基因介导的不亲和互作中,编码NBS-LRR结构的抗病基因参与了寄主对根结线虫的识别,激发了过敏性坏死反应的信号基因,同时多种抗性相关的转录因子基因表达,使以代谢为基础的防御反应和保护机制发挥抗线虫作用。

抑制性差减杂交(SSH)技术在分离植物差异表达基因中的应用

抑制性差减杂交技术(SSH)是基于抑制PCR作用的cDNA差减杂交,是在转录水平上研究差异基因表达的技术。该技术在一个循环过程中完成差异表达基因丰度的均等化及目标群体和对照群体中相同基因的去除,从而实现差异表达基因的高度富集。一个典型的SSH过程,可在一个差减杂交过程中将稀有基因序列富集上千倍。本文通过详细分析该技术在植物差异表达基因分离中的应用发现:SSH技术主要用于分离组织特异性表达和诱导型表达的基因。首先,SSH技术广泛应用在分离植物发育过程中不同发育阶段和不同组织器官中的组织特异性表达的基因,为揭示植物生长发育过程的分子机理提供了有效手段;另外,在不同植物中,该技术被大量应用于分离各种生物及非生物胁迫条件下诱导表达的抗性相关基因,可以揭示植物抗逆的分子机理。目前,SSH技术已开始应用于分离与次生代谢产物合成相关的基因。SSH技术是分离植物差异表达基因,揭示植物复杂生命现象分子机理的有效方法,将在植物差异表达基因研究中得到更广泛的应用。

SSH法获取水稻矮化突变体相关的cDNA片段

利用抑制性消减杂交 (Suppressivesubtractionhybridization ,SSH)分离水稻矮化突变体dwarf69与其野生型对照品系特光矮 2 (Oryzasativa ,TGA 2indica)间表达有差异的cDNA片段。分别以dwarf69作为驱赶子 ,TGA 2为检测子 ,以及以dwarf69作为检测子 ,TGA 2为驱赶子建立了两个差异表达cDNA文库 ,分别代表在TGA 2和dwarf69特异表达的cDNA。经反式Northern检测这两个文库共得到 1 0个阳性克隆。序列分析表明有两个序列为水稻中首次报道 ,一个序列有相应的基因组序列报道 ,但其cDNA序列是首次报道。

辣椒N基因介导抗根结线虫作用早期表达基因的抑制性消减杂交SSH分析

以含N基因的辣椒(Capsicum annuumL.)为试验材料,接种南方根结线虫(Meloidogyne in-cognita)12、24、36h的根尖材料作为测验方(tester),相应的未接种根尖材料作为驱动方(driver),构建一个南方根结线虫诱导N基因表达早期的正向抑制消减杂交cDNA文库,并结合文库高密度点阵膜杂交差异筛选,获得了237条表达序列标签(EST)。在GenBank上进行BLASTn与BLASTx分析,得到148条功能已知的EST序列,获得已知的上调抗性相关EST68个。分离出了具有NBS-LRR结构的抗线虫蛋白和类LRR抗性蛋白的基因,防御作用相关的类萌芽素(GLP)、HSR203J蛋白、蜜腺蛋白、蛇毒素肽等基因,抗性相关的WRKY、ERFBP等转录因子基因,以及G蛋白、14-3-3蛋白等多种信号蛋白基因。通过Gene Ontology分析,N基因介导的早期表达抗病基因涉及病原物的识别、抗性信号传导、过敏性坏死、系统获得性抗性以及植物细胞保护机制等多个方面,并有许多功能未知的基因有待于进一步的研究。

小麦抗白粉病SSH-cDNA文库中差异基因的表达模式

为了解白粉菌诱导下抗白粉病小麦的抗病机制,构建了白粉菌接种初期的抑制性消减杂交cDNA(SSH-cDNA)文库。从中随机挑取140个阳性克隆进行测序,去除冗余序列和重复序列后,得到94条EST,利用NCBI的BLAST在线序列比对工具对GenBank的蛋白质数据库进行同源性比对及功能分类。结果表明,49个EST与已知功能蛋白同源性较高,主要涉及初级代谢(2%)、能量代谢(24%)、细胞结构(2%)、转录(2%)、蛋白质合成加工与储藏(16%)、转运(4%)、信号转导(4%)和抗病与防御(30%)。经文库比较,筛选出与病程相关蛋白基因同源的EST(Z25-1)和与谷胱甘肽硫转移酶同源的EST(Z440-1),GenBank登录号为EX567369和EX567360。以其EST序列为依据设计引物,通过RT-PCR分析它们在白粉菌诱导下的表达模式,结果该2基因表达存在明显差异。其中,Z25-1在未接种白粉菌时具有一定的表达量,白粉菌侵染后表达量开始上升,侵染72h时表达量最高,然后下降;Z440-1在未接种时也具有一定的表达量,但在接种初期表达微弱,甚至不表达,24h后表达开始上升,到72h时达最高,然后下降。本研究表明,病程相关蛋白和谷胱甘肽硫转移酶属于诱导型表达基因,且参与白粉病抗病反应,在白粉菌诱导72h时表达量最高。

黑胫病菌诱导的烟草SSH文库构建及其分析

黑胫病是危害严重的世界性烟草主要病害之一,探究烟草对黑胫病的抗病机制,可以为该病的综合防治提供理论依据。本研究以烟草黑胫病抗性品种革新3号为材料,利用黑胫病0号生理小种诱导其水平抗性,分别在接种后0.5、1、3、6、10和16d取样,通过抑制差减杂交技术(SSH)构建cDNA文库,获得了960个阳性克隆。利用反向Northern斑点杂交技术对其中240个阳性克隆进行杂交筛选,筛选出57个表达差异明显的基因,序列拼接后获得33条高质量EST,测序及其比对分析表明,革新3号对烟草黑胫病抗性相关基因主要涉及抗病防卫、光合作用、信号传导和能量代谢等方面。进一步基因功能分析显示,病程相关PR1b蛋白、半胱氨酸蛋白、延伸因子1-α、α-微管蛋白、细胞色素P450、精胺合成酶、水通道蛋白、过氧化物酶体膜蛋白、甘氨酸延伸因子等可能参与了烟草与黑胫病菌非亲和互作过程。

短枝型苹果SSH文库构建及相关基因表达分析

【目的】寻找苹果短枝型枝条形成相关基因,为进一步探索苹果短枝型芽变形成机理及选育新的短枝型苹果品种奠定基础。【方法】利用抑制性差减杂交技术构建正反向苹果短枝型芽变枝条和正常型枝条差异表达cDNA文库,利用荧光定量RT-PCR验证文库中克隆的插入片段。【结果】从两个文库中共获得291个有效阳性克隆,插入片段大小主要分布在300—600 bp之间。利用GenBank的BLAST比对分析,其中126个表达序列标签(EST)找到了与之匹配的同源序列。获得的cDNA片段功能涉及代谢、转录、胁迫响应、转运、光合和信号转导;有165个EST片段未找到同源序列。对文库中EST序列进行实时荧光定量RT-PCR验证,结果显示这些EST序列在短枝型芽变枝条与正常型枝条之间差异性表达。【结论】通过构建短枝型苹果正反向文库,得到一些与短枝型苹果枝条节间长度相关联的基因,这些基因可能对短枝型苹果枝条的伸长具有一定作用。

青枯菌诱导的花生基因表达谱SSH分析

以抗青枯病花生种质‘J4’和‘中花6号’、感青枯病花生品种‘中花12号’为材料,用强产青枯菌毒菌株(Ralstonia solanacearum)对其根系分别接种,采用抑制差减杂交(SSH)技术检测花生根系应答侵染的基因表达谱变化,并对文库中差异基因进行Real-time PCR分析。结果表明:经菌液PCR检测对挑选出的1 036阳性克隆片段进行测序及片段整合分析,获得162条花生基因,有功能注释的基因58条,其中44条基因参与了细胞结构(6%)、信号转导(12%)、抗病防御(5%)、转录调控(12%)等生理过程。用Real-time PCR技术对7个基因在‘中花6号’和‘中花12号’中的表达模式分析结果表明,6个基因在青枯菌侵染早期在抗病材料‘中花6号’中呈上调表达,可能与青枯病抗性直接相关。

大豆疫霉根腐病菌诱导下SSH文库构建及初步分析

大豆疫霉根腐病是危害大豆生产的毁灭性病害之一，研究利用抑制性消减杂交技术（Suppression Subtractive Hybridization，SSH）成功构建了疫霉菌诱导的大豆抗病品种绥农10差异表达的cDNA消减文库，从文库中共筛选到2067个阳性克隆，PCR鉴定插入片段大部分集中在100—800bp之间，利用BLAST在GenBank数据库进行序列相似性比对，获得有功能的EST375个，分析表明这些EST功能涉及大豆的抑制病原菌生长、细胞自身保护、信号传导、系统获得抗性、蛋白质合成、呼吸作用等。

锌胁迫下小麦SSH文库的构建及初步分析

Zn是植物必需的微量元素,同时也是近年来造成环境污染的重金属元素之一.为了从基因表达水平揭示小麦Zn胁迫响应的分子机制,本研究利用抑制差减杂交(suppression subtractivehybridization,SSH)技术构建了Zn胁迫(0.5 mmol/L,1 mmol/L)下小麦的正反向SSH文库.从正反向文库中随机挑选阳性单克隆,并利用通用引物T7/Sp6对其进行验证.结果显示,正反库中分别获得307和821个EST序列,其片段长度在200～1 000 bp之间,它们反映了Zn胁迫下特异响应的基因.利用BLASTn和BLASTx将这些EST序列进行比对分析,在正、反库中分别筛选出221和641个uniESTs,其中751个uniESTs被注释(包括正库中193个和反库中558个).这些序列的功能主要涉及信号转导、抗氧化防御、转录与翻译、物质运输、核糖体结构、能量代谢,以及一些功能未知的基因.

乙烯诱导下柑橘果实离层SSH文库的构建及分析

为发掘柑橘果实脱落过程中的关键基因,构建了受乙烯诱导的柑橘果实离层SSH文库,经蓝、白斑筛选,菌液PCR检测和测序验证,共获得385条有效EST.经聚类拼接得到单基因簇30个,其中片段重叠群28个、单一EST序列2个.经BLASTX比对NCBI的非冗余蛋白数据库,在这些ESTs中,28个找到同源序列,2个无匹配;BLAST2GO功能注释表明:这些单一基因主要涉及衰老、抗逆防御、细胞壁水解、信号转导等功能.