盐生植物盐爪爪的耐盐生理特性探讨

当前土壤盐渍化日益严重,是限制植物生长的一个主要环境因子,然而在盐碱自然环境中生长着许多耐盐植物,为更好地了解盐生植物的耐盐机理,该文从无机离子Na+,K+,Ca2+含量、脯氨酸水平、水势变化、丙二醛含量和盐胁迫的表型等生理参数以及半定量RT-PCR检测脯氨酸合成关键酶基因(P5CS)的表达规律等方面探讨盐胁迫下盐爪爪的耐盐特性。结果表明:(1)随着盐浓度的升高,Na+在根和肉质化的叶中显著地富集,且叶中积累的Na+比根中更多;(2)在盐胁迫条件下,随着盐浓度的增加,脯氨酸的含量和脯氨酸合成关键酶基因的表达显著地增强;(3)Na+和脯氨酸是植物有效的渗透调节剂,可使处于低水势的植物细胞仍能从细胞外高浓度的盐溶液中吸收水分;(4)在0和700 mmol·L-1Na Cl处理下,盐爪爪肉质化叶中丙二醛的含量较其它处理高,这表明植物在这两个处理下可能受到了氧化胁迫;(5)从盐胁迫3个月的生长表型来看,低盐环境中生长的盐爪爪植株的生物量更多,肉质化的叶嫩且绿。综上所述,结合对野外生境的调查和实验室长期的盐胁迫表型结果表明盐爪爪的生长是需盐的,相对低的盐浓度环境对盐爪爪的生长是顺境,而无盐或高浓度盐环境对于盐爪爪的生长来说都是逆境。该研究结果为全面深入研究盐爪爪的耐盐特性,以及更好地利用盐爪爪的生物和基因资源改良土壤和提高作物和林木的耐盐性奠定基础。     

The Role of Copper Oxide Nanomaterials on Ruta graveolens Physiological Response,and IRT1 and CAT Gene Expression

Background

Copper oxide nanomaterials’ (NMs) are important for the critical roles of Cu as a micronutrient that its improper concentration could cause toxicity or deficiency in plant. The Nano form of CuO could amplify the effects due to special characteristic of nano materials.

Method

Treatments of 0.1, 0.5, and 2.5 μM and NM of copper with three replications were applied to plants under hydroponic conditions. Physiological parameters and expression of IRT1 and CAT genes were investigated.

Results

Copper absorption decreased according to MMs-CuO ? NMs-CuO ?? CuSO4 pattern. The positive effects of MMs-CuO on plant copper content were higher than those of nanomaterials and CuSO4. MMs-CuO effect was more significant on plant biomass increase compared to the control. Rue plant needed lower amounts of copper for better plant growth. The treatments increased protein and carotenoids content in leaves compared with control. Changes in total chlorophyll content under three copper forms were very low and were only increased in leaves at 0.1 μM CuSO4. The NMs-CuO and MMs-CuO similarly reduced leaves’ Cu, MDA and ROS contents, and SOD activities. CAT enzyme activity had a similar pattern in three copper forms. CAT enzyme activity was only induced under the lowest level of three forms, while at other levels of Cu, it was reduced. NMs-CuO had a more negative effect on IRT1 relative gene expression in root compared with other iron forms. The IRT1 relative gene expression in shoots was positively affected under 2.5 μM CuSO4, 0.5 μM MMs-CuO, and 0.1 and 2.5 μM NMs CuO treatments.

Conclusion

The effect of micro- and nano-CuO on physiology and gene expression mechanisms in rue plants is shown to be does-dependent.

     

冻伤蓝变对广义虾脊兰属植物中4种吲哚基衍生物含量的影响

以6种广义虾脊兰属植物和2种树兰亚科植物为材料,利用液相色谱 串联三重四极杆质谱仪(LCMS QQQ)测定了冻伤处理前后花和叶片中靛苷、靛红、靛蓝和靛玉红4种吲哚基衍生物的含量,分析广义虾脊兰属植物吲哚基衍生物的生成及种属间含量的差异。结果显示：(1)4种吲哚基衍生物在所测定的6种广义虾脊兰属植物中均被检出,但在2种树兰亚科植物五唇兰和足茎毛兰中均未被发现。(2)在所测定的6种广义虾脊兰属植物花和叶片中,冻伤处理后的靛蓝、靛玉红和靛红含量均显著上升,而靛苷含量显著下降,同时花中的吲哚基衍生物含量均高于叶片。(3)6种广义虾脊兰属植物花和叶中吲哚基衍生物总含量以黄兰花最高,三褶虾脊兰叶最低。研究表明,冻伤处理引起靛苷向靛蓝的大量转化是导致冻伤后广义虾脊兰属植物组织中呈现出蓝色的主要原因,推测吲哚基衍生物可能也是一类与植物防御相关的化合物,在植物抵御逆境中扮演着重要的角色。     

Effects of cytokinin and senescence-inducing factors on expression of P ARR5 -GUS gene construct during leaf senescence in transgenic Arabidopsis thaliana plants

ARR5-gene expression was studied in the course of natural leaf senescence and detached leaf senescence in the dark using Arabidopsis thaliana plants transformed with the P _ARR5 -GUS gene construct. GUS-activity was measured as a marker of ARR5-gene expression. Chlorophyll and total protein amounts were also estimated to evaluate leaf senescence. Natural leaf senescence was accompanied by the progressive decline in the GUS-activity in leaves of the 2nd and 3rd nodes studied, and this shift of GUS-activity was more pronounced than the loss of chlorophyll content. The ability of the ARR5-gene promoter to respond to cytokinin was not eliminated during natural leaf senescence, as was demonstrated by a cytokinin-induced increase in GUS activity in leaves after their detachment and incubation on benzyladenine (BA, 5 × 10⁻⁶ M) in the dark. Leaf senescence in the dark was associated with the further decrease in the GUS-activity. The ARR5-gene promoter response to cytokinin was enhanced with the increase of the age of plants, taken as a source of leaves for cytokinin treatments. Hence, although the expression of the ARR5 gene reduces during natural and dark/detached leaf senescence, the ARR5-gene sensitivity to cytokinin was maintained in both cases and even increased with the leaf age. This data suggest that the ARR5 gene, which belongs to the type-A negative regulators of plant response to cytokinin, could be a feedback regulator able to prevent retardation by cytokinin of leaf senescence when it is important for plant life. Growth regulators either reduced ARR5 gene response to cytokinin during senescence of mature detached leaves in the dark (SA, meJA, ABA, SP) or increased it (IAA), thus modifying the resulting rate of its expression.     

<Emphasis Type="Italic">ASYMMETRIC LEAVES2-LIKE38</Emphasis> gene,a Member of AS2/LOB family of <Emphasis Type="Italic">Arabidopsis</Emphasis>, causes leaf dorsoventral alternation in transgenic cockscomb plants

ASYMMETRIC LEAVES2-LIKE38/LBD41 gene of Arabidopsis is a member of the ASYMMETRIC LEAVES2 (AS2)/LATERAL ORGAN BOUNDARIES (LOB) domain gene family. To explore ASL38 function, we transformed 35S:ASL38 constructs into cockscomb (Celosia plumosus) plants via Agrobacterium tumefaciens and obtained T1 35S:ASL38 plants. The extremely folded or crinkly leaves were seen in these T1 cockscomb plants. The anatomical analysis of these malformed leaf blades indicated that adaxial cells revealed abaxialized traits, which were never seen in those of wild-type plants. These results suggested that ectopic expression of ASL38 might lead to alternations of dorsoventrality in folded or crinkly leaves of 35S:ASL38 cockscomb. In general, all data showed that ASL38 might be involved in dorsoventral determination in lateral organ development of plants.     

Over-expression of a vacuolar Na<Superscript>+</Superscript>/H<Superscript>+</Superscript> antiporter gene improves salt tolerance in an upland rice

To develop a salt-tolerant upland rice cultivar (Oryza sativa L.), OsNHX1, a vacuolar-type Na⁺/H⁺ antiporter gene from rice was transferred into the genome of an upland rice cultivar (IRAT109), using an Agrobacterium-mediated method. Seven independent transgenic calli lines were identified by polymerase chain reaction (PCR) analysis. These 35S::OsNHX1 transgenic plants displayed a little accelerated growth during seedling stage but showed delayed flowering time and a slight growth retardation phenotype during late vegetative stage, suggesting that the OsNHX1 has a novel function in plant development. Northern and western blot analyses showed that the expression levels of OsNHX1 mRNA and protein in the leaves of three independent transgenic plant lines were significantly higher than in the leaves of wild type (WT) plants. T₂ generation plants exhibited increased salt tolerance, showing delayed appearance and development of damage or death caused by salt stress, as well as improved recovery upon removal from this condition. Several physiological traits, such as increased Na⁺ content, and decreased osmotic potential in transgenic plants grown in high saline concentrations, further indicated that the transgenic plants had enhanced salt tolerance. Our results suggest the potential use of these transgenic plants for further agricultural applications in saline soil.     

Magnesium deficiency in sugar beets alters sugar partitioning and phloem loading in young mature leaves

Magnesium deficiency has been reported to affect plant growth and biomass partitioning between root and shoot. The present work aims to identify how Mg deficiency alters carbon partitioning in sugar beet (Beta vulgaris L.) plants. Fresh biomass, Mg and sugar contents were followed in diverse organs over 20 days under Mg-sufficient and Mg-deficient conditions. At the end of the treatment, the aerial biomass, but not the root biomass, of Mg-deficient plants was lower compared to control plants. A clear inverse relationship between Mg and sugar contents in leaves was found. Mg deficiency promoted a marked increase in sucrose and starch accumulation in the uppermost expanded leaves, which also had the lowest content of Mg among all the leaves of the rosette. The oldest leaves maintained a higher Mg content. [¹⁴C]Sucrose labelling showed that sucrose export from the uppermost expanded leaves was inhibited. In contrast, sucrose export from the oldest leaves, which are close to, and export mainly to, the roots, was not restricted. In response to Mg deficiency, the BvSUT1 gene encoding a companion cell sucrose/H⁺ symporter was induced in the uppermost expanded leaves, but without further enhancement of sucrose loading into the phloem. The observed increase in BvSUT1 gene expression supports the idea that sucrose loading into the phloem is defective, resulting in its accumulation in the leaf.     

Activity and quantity of ribulose bisphosphate carboxylase-and phosphoenolpyruvate carboxylase-protein in two Crassulacean acid metabolism plants in relation to leaf age,nitrogen nutrition,and point in time during a day/night cycle

Activity of ribulose 1,5-bisphosphate (RuBP) carboxylase in leaf extracts of the constitutive Crassulacean acid metabolism (CAM) plant Kalanchoe pinnata (Lam.) Pers. decreased with increasing leaf age, whereas the activity of phosphoenolpyruvate (PEP) carboxylase increased. Changes in enzyme activities were associated with changes in the amount of enzyme proteins as determined by immunochemical analysis, sucrose density gradient centrifugation, and SDS gel electrophoresis of leaf extracts. Young developing leaves of plants which received high amounts of NO ₃ ^- during growth contained about 30% of the total soluble protein in the form of RuBP carboxylase; this value declined to about 17% in mature leaves. The level of PEP carboxylase in young leaves of plants at high NO ₃ ^- was an estimated 1% of the total soluble protein and increased to approximately 10% in mature leaves, which showed maximum capacity for dark CO₂ fixation. The growth of plants at low levels of NO ₃ ^- decreased the content of soluble protein per unit leaf area as well as the extractable activity and the percentage contribution of both RUBP carboxylase and PEP carboxylase to total soluble leaf protein. There was no definite change in the ratio of RuBP carboxylase to PEP carboxylase activity with a varying supply of NO ₃ ^- during growth. It has been suggested (e.g., Planta 144, 143–151, 1978) that a rhythmic pattern of synthesis and degradation of PEP carboxylase protein is involved in the regulation of -carboxylation during a day/night cycle in CAM. No such changes in the quantity of PEP carboxylase protein were observed in the leaves of Kalanchoe pinnata (Lam.) Pers. or in the leaves of the inducible CAM plant Mesembryanthemum crystallinum L.Abbreviations CAM Crassulacean acid metabolism - RuBP ribulose 1,5-bisphosphate - PEP phosphoenolpyruvate - G-6-P glucose-6-phosphate     

过表达或沉默棉花GhPCBER基因株系的获得及其茎叶木质素和木脂素含量研究

编码苯基香豆满苄基醚还原酶(phenylcoumaran benzylic ether reductase,PCBER)的基因PCBER属于PIP亚家族,是苯丙烷代谢途径中参与木脂素合成的关键基因。该研究构建了棉花GhPCBER基因的植物过表达载体并转化拟南芥,同时构建了VIGS(virus induced gene silencing,病毒诱导的基因沉默)载体转化棉花,采用实时荧光定量PCR技术对GhPCBER基因在不同组织中的表达进行分析;对野生型和转基因植株茎叶组织中的木质素和木脂素含量进行测定分析。结果表明:(1)成功构建了GhPCBER植物过表达载体pGWB17-GhPCBRE以及基因沉默重组载体pTRV2-GhPCBER;经遗传转化获得6株转棉花GhPCBER基因抗性拟南芥植株,同时获得15株GhPCBER基因沉默棉花植株(5株为一组)。(2)PCR检测表明,6株转基因拟南芥均为过表达株系,其中株系1、2、3相对表达量更高,且在茎、叶组织中的表达量分别较野生型提高了7～14倍和6～16倍,表明GhPCBER基因成功在拟南芥中过表达;GhPCBER基因沉默棉花植株的茎、叶组织中的表达量分别比野生型棉株约下降12%和26%,表明烟草脆裂病毒(TRV)体系(pTRV2-GhPCBER)成功抑制了GhPCBER基因的表达。(3)转GhPCBER基因拟南芥茎、叶中木质素和木脂素含量较野生型均显著降低;GhPCBER基因沉默棉花植株茎、叶中木质素和木脂素含量较野生型均极显著降低;组织化学染色观察发现GhPCBER基因沉默棉花植株茎秆颜色明显比野生型染色浅,也证明沉默基因棉花植株茎秆中的木质素含量减少。(4)苯丙烷代谢通路中8个相关基因的实时荧光定量PCR分析发现,过表达或抑制GhPCBRE基因均会导致苯丙烷代谢途径发生重新定向。     

致病疫霉效应蛋白Pi16275的功能研究

[目的]分析致病疫霉效应蛋白Pi16275的超量表达对病原菌致病性的影响,明确Pi16275的亚细胞定位,筛选Pi16275在植物中的互作靶标蛋白及靶标蛋白在抵御病原菌侵染过程中的作用,初步揭示Pi16275在病原菌侵染植物过程中的作用机制.[方法]利用农杆菌介导的烟草瞬时表达系统在烟草叶片表皮细胞中瞬时表达Pi162...     

Sulphur deprivation limits Fe-deficiency responses in tomato plants

The aim of this work was to clarify the role of S supply in the development of the response to Fe depletion in Strategy I plants. In S-sufficient plants, Fe-deficiency caused an increase in the Fe(III)-chelate reductase activity, ⁵⁹Fe uptake rate and ethylene production at root level. This response was associated with increased expression of LeFRO1 [Fe(III)-chelate reductase] and LeIRT1 (Fe²⁺ transporter) genes. Instead, when S-deficient plants were transferred to a Fe-free solution, no induction of Fe(III)-chelate reductase activity and ethylene production was observed. The same held true for LeFRO1 gene expression, while the increase in ⁵⁹Fe²⁺ uptake rate and LeIRT1 gene over-expression were limited. Sulphur deficiency caused a decrease in total sulphur and thiol content; a concomitant increase in ³⁵SO₄ ²⁻ uptake rate was observed, this behaviour being particularly evident in Fe-deficient plants. Sulphur deficiency also virtually abolished expression of the nicotianamine synthase gene (LeNAS), independently of the Fe growth conditions. Sulphur deficiency alone also caused a decrease in Fe content in tomato leaves and an increase in root ethylene production; however, these events were not associated with either increased Fe(III)-chelate reductase activity, higher rates of ⁵⁹Fe uptake or over-expression of either LeFRO1 or LeIRT1 genes. Results show that S deficiency could limit the capacity of tomato plants to cope with Fe-shortage by preventing the induction of the Fe(III)-chelate reductase and limiting the activity and expression of the Fe²⁺ transporter. Furthermore, the results support the idea that ethylene alone cannot trigger specific Fe-deficiency physiological responses in a Strategy I plant, such as tomato.     

Synthesis and accumulation of pea plastocyanin in transgenic tobacco plants

The pea plastocyanin gene in a 3.5 kbp Eco RI fragment of pea nuclear DNA was introduced into tobacco by Agrobacterium-mediated transformation. Regenerated plants contained pea plastocyanin located within the chloroplast thylakoid membrane system. Analysis of seedlings from a self-pollinated transgenic plant containing a single copy of the pea plastocyanin gene indicated that seedlings homozygous for the pea gene contained almost twice as much pea plastocyanin as seedlings hemizygous for the pea gene. Homozygous seedlings contained approximately equal amounts of pea and tobacco plastocyanins. The amount of tobacco plastocyanin in leaves of transgenic plants was unaffected by the expression of the pea plastocyanin gene. The mRNA from the pea gene in tobacco was indistinguishable by northern blotting and S1 nuclease protection from the mRNA found in pea. In both pea and transgenic tobacco, expression of the pea plastocyanin gene was induced by light in leaves but was suppressed in roots. Pea plastocyanin free of contaminating tobacco plastocyanin was purified from transgenic tobacco plants and shown to be indistinguishable from natural pea plastocyanin by N-terminal protein sequencing and ¹H NMR spectroscopy.