短时盐胁迫对盐芥和拟南芥抗氧化物酶的影响

本文测定了24h盐胁迫下盐芥(6周)和拟南芥(3周)中超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,分析了盐胁迫下3种抗氧化物酶在两种植物中的响应特征.结果表明,拟南芥叶片中3种酶活性的变化特征为随盐处理浓度增加,SOD呈逐渐上升趋势,CAT呈逐渐下降趋势,POD活性上升幅度较大,且在200mM NaCl处理条件下,SOD和POD活性达到最大;盐芥根中的SOD、POD、CAT本底活性皆高于叶片.随着盐处理浓度增加,SOD活性基本无变化,叶片中的POD活性逐渐降低,CAT活性逐渐增加.而根中的POD活性却出现递增、CAT为先增加后降低现象.盐芥中的SOD本底含量水平高于拟南芥.     

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.     

Isolation and characterization of 4 gametophytic male sterile mutants in Arabidopsis thaliana

In flowering plants, male fertility depends on the formation and development of normal male gametophytes or pollen grains. However, little is known about the molecular mechanisms that regulate the processes. Here, we report the identification of four novel independent Arabidopsis gametophytic male sterile mutants, apam1, apam2, apam3 and apam4 (Arabidopsis pollen abortion mutant). The four mutants that were generated by the insertions of geneand enhancer-trap Ds transposon elements were defective in pollen development. Genetic analysis results showed that all four mutations resulted in the loss of male gametophytic function, but did not affect female gametophytic function, and the Ds elements were linked to the mutations tightly in all four mutants. Localization of the Ds insertion sites by thermal asymmetric interlaced PCR (TAIL-PCR) showed that the Ds elements were inserted in four different loci distributed on three chromosomes, chromosomes II, III and V. In summary, the apam4 is allelic to AHA3, while the other three were located in places where there are no genes that have been known to be involved in pollen development, suggesting that they are novel mutations involved in pollen development.     

水培拟南芥中芥子油苷组成与含量的初步分析

利用HPLC-MS联用分析方法测定了水培拟南芥莲座叶和根中芥子油苷的组成和含量。水培拟南芥莲座叶和根中检测到的主要芥子油苷分别为10种和12种,其中8种为两者共有。脂肪族芥子油苷和吲哚族芥子油苷在莲座叶和根中的含量相差很大,莲座叶中脂肪族芥子油苷含量是根的3.65倍,而根中吲哚族芥子油苷的含量是莲座叶的1.51倍。莲座叶中含量最高的是脂肪族的4-甲基亚磺酰丁基芥子油苷,占芥子油苷总量的42.62%,而根中则是吲哚族的1-甲氧吲哚基-3-甲基芥子油苷的含量最高,占芥子油苷总量的29.37%。     

Light perception in higher plants

Photosynthetic plants depend on sunlight as their energy source. Thus, they need to detect the intensity, quality and direction of this critical environmental factor and to respond properly by optimizing their growth and development. Perception of light is accomplished by several photoreceptors including phytochromes, blue/ultraviolet (UV)-A and UV-B light photoreceptors. In recent years, genetic, molecular genetic and cell biological approaches have significantly increased our knowledge about the structure and function of the photoreceptors, and allowed the identification of several light signal transduction components. Furthermore, this research led to fruitful interaction between different disciplines, such as molecular biology and ecology. It is safe to assume that we can expect more milestones in this research field in the upcoming years.     

Ethylene-induced nitric oxide production and stomatal closure in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> depending on changes in cytosolic pH

We investigated changes in cytosolic pH and nitric oxide (NO) during ethylene-induced stomatal closure in Arabidopsis thaliana using pharmacological, laser scanning confocal microscopy (LSCM), and spectrophotography techniques. Treatment with ethephon (a direct source of ethylene when applied to plants) and 1-aminocycloaminopropane-1-carboxylic acid (ACC, an ethylene precursor) resulted in a rapid accumulation of NO and cytosolic alkalinization in guard cells. Acetic acid (a weak acid) and sodium orthovanadate (NaVO3; a plasmalemma H+-ATPase inhibitor) reduced stomatal closure induced by ethylene and blocked ethylene-induced activity of nitrate reductase. However, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a NO scavenger, had no effect. These results suggest that NO production is downstream of the rise in cytosolic pH in A. thaliana.     

拟南芥温敏雄性不育突变体atms1的获得及表型分析

从甲基磺酸乙酯（ethylmethane sulfonate,EMS）化学诱变建立的野生型拟南芥（Col-0）突变体文库中筛选到1株突变体.在低温16 ℃时,该突变体的雄性育性与野生型没有显著差异,花粉染色呈现100%可育.随着培养环境温度的升高,突变体花粉育性逐渐下降,因此,该突变体为一温敏雄性不育突变体,并被命名为atms1（ambient temperature-sensory male sterility 1,即环境温度敏感雄性不育1）.花药切片结果显示,在23 ℃以下,该突变体花药各个发育时期的形态与野生型花药没有显著的差异;而27 ℃处理1周后的突变体花药呈现多种表型：同一朵花中各个花药的发育时期出现显著分化,花粉母细胞胼胝体单薄,绒毡层发育滞后于同时期的野生型花药.遗传分析确定,atms1的不育表型是由单个隐性核基因控制的.     

两种拟南芥coi1突变体的鉴定与初步分析

COI1(coronatine-insensitive 1)蛋白是茉莉酸信号途径的信号开关,coi1突变体是茉莉酸信号调控机制研究中的重要实验材料。对从拟南芥生物资源中心购买的两种COI1(At2g39940)的T-DNA插入突变体SALK-095916和SALK-045434,通过基因型分析筛选获得了纯合突变体。进一步的基因表达检测和茉莉酸敏感性试验表明,两种纯合突变体中COI1基因的表达量分别约为野生型植株的40%和50%,突变体幼苗对茉莉酸的敏感性显著降低。获得的SALK-095916(命名为coi1-22)和SALK-045434(命名为coi1-23)纯合突变体可以作为实验材料在进一步的茉莉酸信号途径机制研究中使用。     

新疆塔尔巴哈台山南麓拟南芥生存群落的种间联结特征

为揭示影响拟南芥分布的主要生物因素,本研究对塔尔巴哈台山南麓拟南芥(Arabidopsis thaliana)生存群落内16个主要物种做种间联结性分析,结果表明:物种总体联结方差比率为1.474,表现为显著正联结。其中有65.83%的种对表现出正关联,余下表现为负关联;χ2检验为显著或极显著关联的种对有35对,其中正关联26对,负关联9对;有77.5%的种对关联强度指数(OI)0.6,χ2检验联结性多不显著;优势种对间的OI值基本都0.6,多为显著或极显著正联结。去势对应分析表明,主要优势种都聚集在排序图中央,种间联结紧密,而次要种则零散于其周缘,连接性较弱。16个物种分成2个生态种组,但组间界限不明显。拟南芥与群落主要优势种关系密切,对其依赖性较强,表明群落优势种是影响拟南芥生存分布的主要生物因素。