Constitutive Overexpression of Myo-inositol-1-Phosphate Synthase Gene (GsMIPS2) fromGlycine soja Confers Enhanced Salt Tolerance at Various Growth Stages inArabidopsis

The enzymemyo-inositol-1-phosphate synthase (MIPS EC 5.5.1.4) catalyzes the first step ofmyo-inositol biosynthesis, a product that plays crucial roles in plants as an osmoprotectant, transduction molecule, cell wall constituent and production of stress related molecule. Previous reports highlighted an important role of MIPS family genes in abiotic stresses particularly under salt stress tolerance in several plant species; however, little is known about the cellular and physiological functions ofMIPS2 genes under abiotic conditions. In this study, a novel salt stress responsive gene designatedGsMIPS2 from wild soybean Glycine soja07256 was functionally characterized contained an open reading frame (ORF) of 1 533 bp coding a peptide sequence of 510 amino acids along with mass of 56 445 ku. Multiple sequence alignment analysis revealed its 92%-99% similarity with other MIPS family members in legume proteins. Quantitative real-time PCR results demonstrated thatGsMIPS2 was induced by salt stress and expressed in roots of soybean. The positive function ofGsMIPS2 under salt response at different growth stages of transgenicArabidopsis was also elucidated. The results showed thatGsMIPS2 transgenic lines displayed increased tolerance as compared to WT andatmips2 mutant lines under salt stress. Furthermore, the expression levels of some salt stress responsive marker genes, including KIN1,RD29A, RD29B,P5CsandCOR47 were significantly up-regulated inGsMIPS2 overexpression lines than wild type andatmips2 mutant. Collectively, these results suggested thatGsMIPS2 gene was a positive regulator of plant tolerance to salt stress. This was the first report to demonstrate that overexpression ofGsMIPS2 gene from wild soybean improved salt tolerance in transgenicArabidopsis.     

低温条件下一氧化氮参与了水杨酸对拟南芥生长的抑制作用

[目的]验证NO是否参与了水杨酸对拟南芥生长的抑制过程,为植物在长期低温下生长的分子机制研究奠定基础。[方法]用可渗透细胞膜的NO特异性探针DAF-FMDA染色法测定4℃低温处理下,野生型拟南芥（Arabidopsis thaliana）和NahG突变体根中内源NO含量的变化。[结果]长期低温4℃处理可诱导植物中NO含量增加,并随时间的延长而升高;低温能够诱导野生型和NahG突变体中NO的产生,但体内水杨酸含量低的NahG突变体中NO含量明显低于比野生型。[结论]低温条件下NO参与了水杨酸对拟南芥生长的抑制过程。     

Methyl jasmonate and methyl salicylate, but not cis-jasmone, evoke defenses against infection of Arabidopsis thaliana by Orobanche aegyptiaca

The mechanism by which some plant species develop resistance to the root parasite, broomrape ( Orobanche aegyptiaca ), is still not clear. Resistance to other pathogens can be induced by methyl jasmonate and systemic acquired resistance can be induced by treatment with salicylic acid, while cis -jasmone can act as a signaling molecule in plant–insect interactions. The three compounds studied, methyl jasmonate, cis -jasmone, and methyl salicylate, were applied to Arabidopsis thaliana seedlings that were then transferred to Nunc cell culture plates and exposed to the germinating seeds of O. aegyptiaca . The number of infections of the roots of single seedlings of A. thaliana was then quantified. Exposure for 24 h to very low concentrations of methyl jasmonate or methyl salicylate, which were then removed, effectively induced resistance to infection of A. thaliana by O. aegyptiaca , reducing attachment and tubercle formation by 90%. cis -Jasmone was far less effective in inducing a similar resistance to infection. These results support the view that methyl jasmonate can induce almost full resistance to infection by broomrape. The fact that such resistance is not observed under normal conditions of infection supports the idea that the root parasite does not evoke the full defensive response in the host plant.     

蓝莓Vco-miR_n10的克隆及对干旱的响应分析

【目的】MicroRNA（miRNA）是一类内源单链非编码的小分子 RNA，在动植物中参与转录后基因 表达调控。Vco-miR_n10 是蓝莓中的新型 miRNA，目前尚未见该 miRNA 功能方面的报道。本研究对蓝莓 VcomiR_n10 进行了初步功能分析。【方法】基于前期蓝莓小 RNA 高通量测序结果，对鉴定到的蓝莓新型 miRNA （Vco-miR_n10）的前体序列（224 nt）进行克隆与测序，并利用 mfold 在线软件对其前体序列的二级结构进行 预测。采用 Gateway 系统构建了 35Spro:: pre-Vco-miR_n10 表达载体并转入野生型拟南芥中，对其正常生长及 300 mmol/L 甘露醇处理条件下的表型进行观察与分析。【结果】克隆获得了 Vco-miR_n10 的前体序列，该序列能够折 叠形成较完美的茎环结构且仅有 2 个错配碱基对。Vco-miR_n10 的成熟体序列位于 3'' 茎臂上。观察正常生长条 件下的转基因植株并无显著的表型变化。而在 300 mmol/L 甘露醇模拟的干旱条件下，Vco-miR_n10-24 与 VcomiR_n10-52 的发芽率（33.53%、37.69%）和绿苗率均显著低于野生型（发芽率 67.72%、绿苗率 66.33%）。【结 论】蓝莓 Vco-miR_n10 能够响应甘露醇模拟的干旱胁迫，并降低拟南芥对干旱的耐受能力，影响发芽率和绿苗率， 说明蓝莓 Vco-miR_n10 可能在植物响应干旱胁迫过程中发挥一定的调控功能。     

拟南芥晚花突变体的筛选

在植物的生命周期中从营养生长到开花是发育过程的重要转折。花启动的时机对生殖生长的成功至关重要。植物开花时间突变体的获得,在揭示植物花发育的奥秘中起了十分重要的作用。本研究以模式植物拟南芥(A rabid op sis tha liana)为材料,将野生型拟南芥(Co lum b ia生态型)的种子用甲基黄酸乙酯(EM S)诱变处理,将经诱变处理的种子M1播种收获M2种子用于突变体筛选。以初生莲座叶片数作为筛选指标,筛选出一株晚花突变体,命名flx(flow ering locus x)。     

ABA在拟南芥种子萌发和幼苗发育中的作用

采用不用浓度ABA处理各种基因型的拟南芥种子,结果表明:拟南芥abi1和abi2是ABA信号的负调节者;异三聚体G蛋白α亚基gpa1基因超表达株系和T-DNA插入突变体在种子萌发和幼苗发育中对ABA不敏感;相对于野生型来说,a/c、a/g表现出相对的ABA不敏感性,表明在ABA抑制的种子萌发和幼苗发育过程中gap1可能位于abi1上游。     

过量表达甜菜BvNHX1基因提高拟南芥的耐盐性

Na+/H+逆向转运蛋白调节细胞内的离子平衡,在植物耐盐性起重要的作用。为了研究甜菜液泡膜Na+/H+逆向转运蛋白BvNHX1基因在植物耐盐中的作用,构建了植物表达载体pROKⅡ-BvNHX1转化拟南芥.在含有卡纳霉素的培养基上筛选转化子,并利用Southern和Northern杂交技术检测,进一步证实BvNHX1基因已整合到拟南芥基因组并能正常转录。选取纯合转基因株系进行耐盐性分析实验表明,过量表达BvN-HX1基因的拟南芥在种子萌发和苗期都提高了植株耐盐性,盐处理下转基因植株的鲜重、干重以及地上部分Na+、K+含量均高于野生型对照。结果表明过量表达BvNHX1基因提高了转基因拟南芥的耐盐能力。     

镉诱导拟南芥根尖过氧化氢积累导致植物根生长抑制

以模式植物拟南芥为材料研究了植物主根对不同浓度镉胁迫的响应。结果表明,随镉浓度的升高,植物主根生长受到明显抑制,胎盘兰染色表明高剂量的镉造成主根根尖细胞死亡。进一步二氨基联苯胺(DAB)染色发现镉胁迫诱导植物根尖大量积累过氧化氢,而在胁迫培养基中加入维生素C可显著改善植物根的生长、降低过氧化氢积累,并减少镉诱导的根尖细胞死亡。上述结果表明,镉胁迫诱导的拟南芥主根生长抑制很可能是由于根尖细胞过氧化物积累所致。     

基因芯片在拟南芥非生物胁迫响应中的应用

为更好地理解作物响应及耐受胁迫的分子机制,利用非生物胁迫诱导表达基因提高作物的抗逆性,从而对作物进行遗传改良,创制抗逆能力强的新品种。以模式植物拟南芥为例,综述了基因芯片在非生物胁迫中的应用进展,并对基因芯片差异表达在作物响应及耐受胁迫研究中的应用前景进行展望。