拟南芥SnRK2.2/2.3激酶参与调节镉胁迫响应的机制探究

为探究拟南芥SnRK2.2和SnRK2.3基因对Cd胁迫响应的分子机制. 以野生型（WT）、双突变体SnRK2.2/2.3、过表达SnRK2.2和过表达SnRK2.3的转基因植物为材料,研究SnRK2.2和SnRK2.3基因与Cd胁迫响应的关系.发现过表达两个基因可以提高拟南芥对Cd的耐受性,表现为可以减少Cd、丙二醛（MDA）及活性氧（ROS）的累积量,增加抗氧化酶CAT、POD和SOD的活性. qRT PCR结果显示在Cd胁迫下,两种过表达植株中铁转运蛋白IRT1和转录因子FIT、bHLH038和bHLH039表达水平受到明显抑制,ABA合成相关基因AAO3和NCED3的表达量显著上调.在Cd胁迫下,两种过表达植株中ABA含量显著高于WT和双突变体. 以上结果表明：拟南芥遭受Cd胁迫时,SnRK2.2和SnRK2.3基因通过下调IRT1基因表达从而减少植物对Cd的吸收,同时通过增加内源ABA含量来缓解Cd对植物的毒害.     

拟南芥中参与盐胁迫应答的基因 At1g14260的功能初探

拟南芥中未知基因At1g14260的表达受到多种非生物胁迫的诱导, 特别是在NaCl的诱导下, At1g14260的表达量明显增加. 对T DNA插入突变体at1g14260(salk 118406)的分析表明, 敲除了基因At1g14260的拟南芥相比野生型对盐胁迫更加敏感. 此外, 构建了融合表达载体PBi221 At1g14260 GFP并且成功转入拟南芥原生质体中, 在荧光显微镜下观察到融合蛋白定位于原生质体细胞核中. 因此, At1g14260可能参与了拟南芥中盐胁迫的过程.     

盐胁迫下拟南芥去乙酰化酶调控下游基因表达的转录组分析

胁迫是指植物持续地暴露在环境的刺激下,有能力建立保护和适应的机制。组蛋白的去乙酰化作为一种表观遗传现象,在植物适应环境中发挥了重要的作用。为了探究高盐胁迫下,组蛋白的去乙酰化酶在植物抵御和适应高盐胁迫中的作用,本研究以拟南芥野生型WT和四突（h2tq,HD2四个基因的突变体）为材料,采用RNA-seq技术和生物信息学方法,对生长10d的幼苗在高盐（150 mM NaCl）处理前和后进行比较转录组分析,并结合实时荧光定量PCR验证转录组数据的可靠性。结果显示：在高盐处理前WT和hd2q共有25个差异基因,其中上调基因2个,下调基因23个。在高盐处理后,WT和hd2q共有1407个差异基因,其中上调基因772个,下调基因635个。GO和KEGG分析显示,对照的差异基因主要富集在胞外区域和响应脱落酸上,盐处理的差异基因主要富集在胞外区域和细胞壁上。植物响应盐胁迫是一个涉及不同交叉途径的复杂过程,这些结果可为研究表观遗传在盐胁迫逆境下的刺激响应提供一定参考意义。     

拟南芥AtHHR2基因的功能初步研究

为了研究拟南芥Highly Homologous RING domain 2基因(At5g43200)在盐胁迫逆境的功能,通过DNA及RNA水平鉴定了该基因的T-DNA插入突变体athhr2,并通过根瘤农杆菌介导法进行遗传转化,筛选获得了athhr2/ATHHR2互补转基因株系.对突变体、互补转基因株系及野生型进行盐胁迫处理,对其萌发率、脯氨酸及叶绿素水平进行检测,发现盐处理后缺失突变体的萌发率降低,脯氨酸和叶绿素含量低于野生型,互补株系的萌发率、脯氨酸和叶绿素含量均高于野生型.以上结果证明AtHHR2基因在拟南芥的盐胁迫响应中起正调控作用.     

拟南芥AtHHR3响应热胁迫应答的初步分析

拟南芥基因AtHHR3编码一个RING结构域的E3连接酶,通过生物信息学分析发现其可能参与植物热胁迫相关的应答.为了探索其具体的功能,构建了AtHHR3互补株系,并在DNA水平和转录水平分别鉴定了AtHHR3互补株系,用RT-PCR技术分析了AtHHR3在热处理条件下基因表达的变化情况.在热胁迫下分析了野生型、突变体athhr3、回复株系幼苗存活以及种子萌发的表型变化情况,发现突变体athhr3表现出对热胁迫的耐受性,并检测了热胁迫下不同株系的HSF、HSP等热相关基因的转录水平的变化,初步的研究表明拟南芥基因AtHHR3负调控植物对热胁迫的耐受性.     

NaCl对拟南芥(Arabidopsis thaliana)生长与渗透调节的影响

对与拟南芥耐盐性相关的某些生理指标进行了研究。结果发现,随着盐浓度的增加,拟南芥的质膜透性增加,MDA含量、脯氨酸含量、可溶性糖含量、有机酸含量、游离氨基酸含量、根冠比、钠离子含量均增加,而渗透势、钾离子含量、干鲜重、含水量则下降。这表明,随着盐胁迫的加重,一方面拟南芥受到的伤害加重,另一方面植株通过合成脯氨酸、可溶性糖等渗透调节物质,增大根冠比以提高吸水能力等抗逆机制,以应对胁迫,提高耐盐性。     

拟南芥抗油菜黑胫病突变基因的遗传分析及染色体定位

以拟南芥黑胫病感病突变体及抗病野生型为材料,对不同世代群体进行遗传分析,结果表明,该突变性状为细胞核内两对重叠作用的基因所控制,感病植株为隐性突变体,其基因型为sc1sc2.同时对突变位点sc1及sc2进行了染色体定位研究.结果证实, sc1位于1号染色体的长臂上,sc2位于2号染色体的长臂上.为进一步研究拟南芥抗病功能基因奠定了基础.     

HD2基因调控拟南芥下胚轴发育的功能研究

为探究组蛋白去乙酰化酶HD2基因在拟南芥下胚轴发育中的调控作用,本研究采用野生型（Col-0）、HD2突变体以及过表达植株为材料,研究其在1/2MS以及1/2MS+100 mmol/L甘露醇培养中下胚轴的表型特征,并结合转录组测序数据进一步分析. 实验结果显示,四种过表达株系下胚轴长度较Col-0长,伸长百分比为7.1%～19.5%,差异显著;甘露醇处理后,过表达植株下胚轴较Col-0更长,伸长百分比为14.6%～32.8%,差异更加显著,缩短幅度也更小. hd2a/hd2b和hd2a/hd2c双基因突变体植株在有无甘露醇时,下胚轴长度均显著短于Col-0,但干旱胁迫后变短幅度无明显增加. 转录组数据揭示,HD2基因调控光合系统响应基因影响植株暗形态建成反应,从而影响下胚轴发育. 甘露醇处理后,HD2基因诱导产生非生物刺激响应因子,帮助下胚轴抵抗不良环境. 综上所述,HD2基因在拟南芥下胚轴发育中承担重要调控作用.     

拟南芥谷氨酰tRNA合成酶同其相互作用蛋白VDAC的转录水平分析

本研究在基于前期对拟南芥VDAC（电压依赖性阴离子通道蛋白质）与AtGluRS（谷氨酰tRNA合成酶）两种基因的过量表达和抑制表达转基因突变体株系的初步生理性状分析基础上,对筛选获得的转基因T1代植株以及拟南芥abi1、abi2突变株,进行转录水平两种蛋白特异性基因片段的地高辛标记Northern杂交以及半定量RTPCR分析.结果显示,在拟南芥abi1、abi2突变株中,VDAC和AtGluRS两种基因的转录表达均收到不同程度的抑制;而VDAC与AtGluRS两种基因之间存在间接或直接的正调控关系,进一     

Involvement of DEG5 and DEG8 proteases in the turnover of the photosystem II reaction center D1 protein under heat stress in Arabidopsis thaliana

Deg5,deg8 and the double mutant,deg5deg8 of Arabidopsis thaliana were used to study the physiological role of the DEG proteases in the repair cycle of photosystem II (PSII) under heat stress. PSII activity in deg mutants showed increased sensitivity to heat stress, and the extent of this effect was greater in the double mutant, deg5deg8, than in the single mutants, deg5 and deg8. Degradation of the D1 protein was slower in the mutants than in the WT plants. Furthermore, the levels of other PSII reaction center proteins tested remained relatively stable in the mutant and WT plants following high-temperature treatment. Thus, our results indicate that DEG5 and DEG8 may have synergistic function in degradation of D1 protein under heat stress.     

细胞自噬在植物应答盐胁迫中的作用研究

本研究以模式植物拟南芥为材料,利用生理学和遗传学手段分析了盐胁迫下细胞自噬基因和活性氧(ROS)变化的相关性.结果表明野生型拟南芥Col-0在遭受盐胁迫处理3d表现了叶片漂白的症状并且会诱导ROS的产生和积累了大量的细胞死亡.荧光定量PCR实验表明盐胁迫会诱导细胞自噬相关基因的表达,细胞自噬参与了调控植物的防御机制来响应盐胁迫.进一步的实验表明拟南芥细胞自噬突变体atg2和atg5在遭受盐胁迫处理3d表现了更加严重的叶片漂白症状并且积累大量的细胞死亡和ROS.初步表明细胞自噬主要是通过调控ROS的产生来应答盐胁迫.     

Physiological response of natural plants to the change of groundwater level in the lower reaches of Tarim River, Xinjiang

Based on the analysis of the three-year (2000-2002) monitoring data of the four times intermittent stream water conveyance to the lower reaches of Tarim River where the stream flow was dried up for more than 30 years and the measurement of PRO, SOD and POD in plants collected from 24 vegetation plots, it is concluded that the stream water conveyance plays an important role in lifting groundwater level. The groundwater nearby the watercourse was raised from 5～8 m in depth before the stream water conveyance to 2.5～5 m after stream water conveyance. The physiological response of Phragmites communis, Tamarix spp. And Populus euphratica to the change of groundwater is sensitive and represents a grads change obviously. The growth of the plants in the lower reaches of Tarim River is stressed by drought to various degrees. Lengthways, the drought stress exposed to the plants increases with groundwater depth from the upper sections to the lower sections; and breadthwise, the drought stress exposed to the plants is increased with the increase of distance away from the river channel of stream intermittent water releases and of the groundwater depth. Combining the field investigation and the analysis of the plots, it is considered that the stress groundwater depths for the Phragmites communis, Tamarix spp. And Populus euphratica are 3.5 m, 5 m and 4.5 m respectively.     

Twenty-five years of change in scleractinian coral communities of Daya Bay （northern South China Sea） and its response to the 2008 AD extreme cold climate event

Coral reefs worldwide are becoming increasingly and detrimentally impacted upon by a variety of factors including significant climate changes, such as global warming and increased El Nino-Southern Oscillation activity. Generally, the persistence of coral reefs, especially at low-latitudes, is governed, in part, by sea surface temperatures not exceeding the critical limit （-30℃） at which mass mortality can occur. Thus, it is thought that corals living at high-latitudes （i.e., currently cooler sea surface temperatures） will likely respond more favourably to hypothesized future temperature increases than corals living at low-latitudes （i.e., currently warmer sea surface temperatures）. Consequently, high-latitude coral communities may have the potential to act as regions of refugia for many coral species in the face of potential future global warming. The Daya Bay （22°31′--22°50′N）, northern South China Sea, contains several high-latitude non-reefal coral communities and represents one of the most northerly distributions of scleractinian corals within the region. Significantly, Daya Bay has experienced dramatic warming in both air and sea surface temperatures throughout the past 50 years. In this paper, we analyze 25 years of change in the Daya Bay coral communities, based both on historic surveys and our latest 2006--2008 regional ecological surveys. Our results suggest that, contrary to predictions, there have been significant declines in coral cover within the Daya Bay during the past 25 years （i.e., 76.6% coral cover in 1983/1984 to only 15.3% coral cover by 2008）. Such changes also reflect a significant shift in the most abundant coral species, from Acropora pruinosa to Favites abdita. Most of the modern coral communities became established between 15 and 30 years ago, corresponding to a period of increased winter sea surface temperature. However, very few colonies have become established within the last 15 years, despite a more intense period of warming. By taking into account additional factors, we hypothesize that direct anthropogenic impacts, rather than climatic events, have both restricted the development, and drove the decline, of Daya Bay coral communities in the last 15 years. The Daya Bay has also been subjected to occasional extreme cold events during the past 50 years, with the most recent occurring in early 2008 （13 January-13 February）. During the 2008 cold event, the lowest air temperature reaches only 6.6℃, and the mean sea surface temperature for February fall to 〈 14℃, including six continuous days at 12.3℃. Significantly, the sea surface temperatures fall below the hypothesized critical lower temperature threshold （-13℃） that commonly leads to mass mortality in scleractinian coral communities. Surprisingly, our coral community surveys, conducted both before （August 2007） and after （late February 2008） the extreme 2008 cold event, demonstrate that the Daya Bay coral ecosystems are barely impacted upon during the cold period. Those observations suggest that the Daya Bay scleractinian coral communities have developed adaptations to low sea surface temperatures. Overall, our data support the hypothesis that high-latitude coral communities, such as Daya Bay, have the potential to act as areas of refugia for scleractinian corals in the advent of potential future global warming.     

用基因芯片技术分析干旱胁迫下生殖生长期大麦的基因表达

耐旱性是干旱地区稳定和增加大麦产量的一个关键因素。鉴定出与耐旱性相关的功能基因,一方面可了解大麦的耐旱机理,同时还可以促进利用生物技术来改良大麦的耐旱性。在研究中,2个在耐旱性上具有明显差异的大麦品种Tadmor(耐旱)和WI2291(干旱敏感)被选作材料,采用22000个ESTs(基因表达序列标签)的Affymetrix大麦基因芯片Barley1来分析生殖生长期干旱胁迫下2个大麦材料的差异表达基因。研究结果表明,干旱胁迫下2个大麦材料中有77个共调节基因,其中部分基因已被报道过可能与抗旱性相关。这些基因中已有功能注释的基因按其生物学功能被分为14组,猜测它们是干旱胁迫的响应基因,在抗旱性上可能不起重要作用,或者是必需的但单独不足以提高大麦的抗旱性。进一步比较2个材料差异表达的基因,发现二材料之间有372个受干旱调节基因的差异。这些基因中有功能注释基因的生物学功能中可分为15组,其中一些已被认为与抗旱性相关;而对那些未知功能的基因,推测可能亦在大麦的抗旱性上扮演一定的角色。研究所得结果可为阐述生殖生长期大麦的耐旱性机理提供新的认识。