热激转录因子在植物抗非生物胁迫中的功能研究进展

植物在遭受环境胁迫时会产生一系列应激反应,而热激转录因子可通过介导热激蛋白或其他热诱导基因的转录和表达,来参与调控植物抵抗逆境胁迫过程和其他生命活动。主要介绍了植物热激转录因子的基本蛋白结构域,阐述了3类热激转录因子在抗极端温度（高温、低温）胁迫、干旱胁迫、高盐胁迫、活性氧胁迫中的功能与作用机制,并探讨和展望了植物热激转录因子在植物育种和提高植物抗逆性的研究中的发展与应用前景,以期为深入研究热激转录因子在调控植物抵抗逆境胁迫中的生物学功能与机制提供理论参考。     

逆境胁迫对水稻DNA甲基化水平的影响

植物在逆境胁迫下发生复杂的表现遗传变化,包括DNA甲基化、组蛋白修饰和RNA介导的基因沉默等.其中DNA甲基化是表现遗传学中的重要组成部分,主要通过甲基化、去甲基化来参与逆境胁迫下基因表达的调控,进而增强植物体的抗逆性,调节植物体的生长发育.就非生物与生物胁迫对水稻DNA甲基化水平的影响进行综述,为从表观遗传水平研究水稻抗逆性的机制提供理论参考.     

microRNA在植物逆境胁迫应答中的作用

逆境胁迫严重影响着全世界范围内的作物产量。为减少逆境胁迫损伤,植物在长期的进化过程中形成了多级别（转录、转录后和翻译、翻译后）的基因表达调控应答机制。最近研究发现,内源microRNA（miRNA）在植物逆境胁迫应答中具有重要的调节作用。在逆境胁迫发生时,一些miRNA会表达上调,而另一些miRNA会表达下调;miRNA正是通过下调胁迫应答过程的负调节子靶基因和上调胁迫应答过程中的正调节子靶基因,来执行生理调控功能。通过综述miRNA在植物逆境应答中的作用,以期全面的了解逆境胁迫调控网络。     

基于丙酮酸累积的真菌抗逆机制

环境中的真菌经常会遇到多种非生物逆境胁迫,对真菌耐受逆境胁迫的机制已开展大量研究。在多种不同的真菌中发现热胁迫会诱发丙酮酸快速累积。在罗伯茨绿僵菌中,累积的丙酮酸能及时消除热胁迫诱导产生的活性氧自由基(ROS),降低ROS所引起的蛋白质羰基化修饰水平,并抑制线粒体膜电位崩溃,从而提高真菌的耐热能力。高渗、氧化胁迫和紫外线辐射也会诱发丙酮酸累积,并消除产生的ROS,这是丙酮酸累积参与多逆境交叉保护的一个机制。通过基因工程技术改造丙酮酸代谢途径,提高了在最适温度下分生孢子中丙酮酸的含量。遗传改良的孢子中丙酮酸能够快速有效地消除由热处理诱发产生的ROS,降低了ROS对分生孢子的损伤,进而提高了孢子对热胁迫的耐受性,为创建高效的真菌杀虫剂提供了菌株。     

植物应答逆境胁迫的蛋白质组学研究进展

逆境胁迫是制约植物生长发育、影响作物产量和质量的关键因子,揭示植物应答胁迫的分子机理一直是人们长期探索的重大课题.随着拟南芥、水稻等模式植物基因组测序的完成,植物基因组学的研究重点已经转变为功能基因组学研究,蛋白质组学是后基因组时代的新兴研究领域,它有助于人们从分子水平上了解植物耐受胁迫的机制.介绍了植物应答非生物胁迫,如盐胁迫、温度胁迫、干旱胁迫、营养胁迫和机械伤害等,以及生物胁迫,如病菌侵害的蛋白质组学最新研究进展,并探讨了利用蛋白质组学技术研究植物抗逆性方面的优势和前景.     

光学无损分析技术在植物铝毒性研究中的应用

光学技术以它所特有的无损、快速和在位分析的优势,广泛应用于植物逆境生理监测和逆境胁迫机制研究.作为一类最主要的逆境胁迫,铝毒性是酸性土壤限制作物生长的主要原因.本文从光学分子成像和在位实时监测两个功能层面上概述了光学分析技术在铝毒生物学机制研究和铝毒性生理探测中的应用,并对其做了展望,同时,也讨论了铝毒性生物胁迫机制尚未涉及的问题,以期为铝胁迫机制研究提供有用的技术和理论参考.     

基因芯片研究植物逆境基因表达新进展

逆境胁迫影响植物的正常生长, 导致作物减产, 甚至绝收。提高作物的抗逆性一直是作物遗传育种学家追求的目标, 大量研究也正试图揭示这一复杂的生物学机制。传统的从生理生化水平到单一基因的研究都难以揭示植物复杂的抗逆机制, 而基因芯片(Gene chip)的应用使得这一目标成为了可能, 基因芯片从整个转录水平入手, 能够揭示大量基因的表达和调控情况, 同时结合蛋白质组学和代谢组学的研究方法, 将基因定位于代谢途径的某个位置, 寻找逆境胁迫响应的关键基因, 完善植物逆境胁迫响应的分子网络, 为今后利用生物技术手段提高作物抗逆境胁迫能力提供依据。文章主要对近年来基因芯片在植物逆境胁迫基因表达研究中的进展进行了综述。     

植物逆境胁迫耐受性启动子的研究进展

逆境胁迫如干旱、极端温度、损伤等非生物胁迫和病虫害等生物胁迫严重影响植物的生长发育及产量。逆境胁迫耐受性启动子能够接受逆境条件下的诱导信号,激活植物体内胁迫应答基因的表达,使植物感知并适应逆境。本文对逆境胁迫耐受性启动子的克隆及功能研究情况进行综合分析,主要包括抗旱、耐盐、耐高温、抗冻、耐损伤、抗病和抗虫基因启动子。     

海水胁迫对向日葵苗期生长及矿质营养吸收特性的影响

采用砂培法,研究了海水胁迫对向日葵幼苗生长及矿质营养吸收特性的影响。结果表明,海水胁迫下,向日葵幼苗株高、茎粗、干物重明显降低。幼苗根茎叶中Cl-,茎和叶中Mg2 、叶中Na 和Ca2 含量随海水浓度的增加而增加,根茎叶中K 、全氮和全磷含量随海水浓度升高而降低,但在10%和20%海水胁迫下,向日葵体内Na 、Cl-主要集中于根和茎中,叶中较少。海水胁迫下,向日葵幼苗各部位K /Na 始终是叶部最高,根部最低,且根茎叶中SK,Na值均大于1。因此,低浓度海水胁迫下向日葵幼苗对Na 和Cl-的截流作用、海水胁迫下幼苗根部对K 强的选择性吸收以及K 向地上部的选择性运输是向日葵具有一定耐盐性的主要原因。     

植物逆境胁迫相关蛋白激酶的研究进展

干旱、高盐、高温和低温等非生物胁迫及各种病虫害等生物胁迫严重影响植物的生长发育和作物产量.蛋白激酶主要通过激活不同的磷酸化途径介导外界环境信号的感知和传递,调控下游抗逆基因的转录表达,启动相应的生理生化等适应性反应来降低或消除危害.该文对近年来国内外有关与非生物胁迫和生物胁迫信号传导相关的受体蛋白激酶、促分裂原活化蛋白激酶、钙依赖而钙调素不依赖的蛋白激酶、蔗糖不发酵相关蛋白激酶和其它胁迫相关的植物蛋白激酶的研究进展进行综述,探索蛋白激酶介导的不同磷酸化途径应对逆境胁迫的信号传递网络,为进一步了解植物逆境分子应答机制提供依据.     

向日葵列当生物学特性及抗列当向日葵分子育种研究进展

向日葵是世界各国重要的油料作物,也是供食用的重要经济作物。向日葵列当是危害向日葵生长极为严重的一类草害,在全球均有发生,且列当种子生活力极强,难以根除。向日葵列当研究和抗列当向日葵育种是农业科研人员研究的重点。本文综述了向日葵列当的生物学特性、寄生与传播特点、为害症状、预防和控制措施,以及近来年抗列当向日葵分子育种研究进展,并对抗列当向日葵育种研究发展前景作分析和展望。     

Influence of thiourea application on some physiological and molecular criteria of sunflower (Helianthus annuus L.) plants under conditions of heat stress

High temperature is a major factor limiting the growth of plant species during summer. Understanding the mechanisms of plant tolerance to high temperature would help in developing effective management practices and heat-tolerant cultivars through breeding or biotechnology. The present investigation was carried out to study the role of thiourea in enhancing the tolerance of sunflower plants to heat stress. Sunflower plants were subjected to temperature stress by exposing plants to 35 or 45 °C for 12 h. Two levels of thiourea (10 and 20 mM) were applied before sowing (seed treatment). The results indicated that the plants exposed to temperature stress exhibited a significant decline in growth parameters, chlorophylls, relative leaf water content, oil content, leaf nutrient status, and nitrate reductase activity. Treatment with thiourea, especially when applied at 10 mM, improved the above parameters and induced non-enzymatic and enzymatic antioxidants responsible for antioxidation. SDS-PAGE of protein revealed that high-temperature treatments alone or in combination with thiourea were associated with the disappearance of some bands or the appearance of unique ones. The result of RAPD analysis using five primers showed variable qualitative and quantitative changes. These findings confirm the effectiveness of applying thiourea on alleviating heat injuries in sunflower plants.     

Improved salinity tolerance and growth performance in transgenic sunflower plants via ectopic expression of a wheat antiporter gene (TaNHX2)

Molecular Biology Reports - Sunflower (Helianthus annuus. L) is one of the principal oil seed crops affected by the salinity stress, which limits the oil content and crop yield of sunflower plants....     

向日葵对苯胺废水的光合生理响应及净化效果

为探讨向日葵对苯胺废水的耐受性及其应用于苯胺污染废水植物修复的可行性,采用水培试验方法,以美国油葵1号为材料,研究了不同苯胺浓度胁迫对向日葵光合和叶绿素荧光参数的影响,以及向日葵对苯胺的吸收、积累和净化效果。研究发现:100 mg/L的苯胺对向日葵的净光合速率(P_n)、气孔导度(L_s)和蒸腾速率(T_r)有显著的促进作用,而对生长与叶绿素荧光相关参数无显著的影响。当苯胺浓度升高到200—400 mg/L时,向日葵的鲜重、净光合速率(P_n)、实际光化学效率(Φ_(PSⅡ)),最大光化学效率(F_v/F_m)以及光化学淬灭系数(qP)比对照组显著降低,而胞间CO_2浓度(C_i)显著升高,NPQ呈现出先升高后降低的趋势,并在苯胺浓度为200 mg/L时达到最大值。综合分析表明,当苯胺浓度升高到200 mg/L到400 mg/L时,苯胺对向日葵的净光合速率的抑制以非气孔因素为主。当苯胺浓度为500 mg/L时,导致向日葵死亡。另外,向日葵对100 mg/L苯胺废水中苯胺的去除率最高,达到80.97%。苯胺主要在向日葵的地上部分积累,随着苯胺浓度的升高,向日葵中叶片苯胺的浓度逐渐升高,茎中的苯胺含量变化不显著,而根中的苯胺含量较低。     

Metal accumulation and response of antioxidant enzymes in seedlings and adult sunflower mutants with improved metal removal traits on a metal-contaminated soil

Sunflower mutant lines with an enhanced tolerance and metal accumulation capacity obtained by mutation breeding have been proposed for Zn, Cd and Cu removal from metal-contaminated soils in previous studies. However, soils contaminated with trace elements induce various biochemical alterations in plants leading to oxidative stress. There is a lack of knowledge concerning the metal accumulation and antioxidant responses during the growth and development of sunflowers. This study, therefore, aimed to characterise metal accumulation and possible metal detoxification mechanisms in young seedlings and adult sunflowers. Beside the inbred line, two mutant lines with an improved growth and enhanced metal uptake capacity on a metal contaminated soil were investigated in more detail.Sunflowers cultivated on a metal-contaminated soil in the greenhouse showed a decrease in shoot biomass and chlorophyll concentration in two different developmental stages. Adult sunflowers showed a lower sensitivity to metal toxicity than young seedlings, whereas mutant lines were more tolerant to metal stress than the control. Mutant lines also produced a higher amount of carotenoids on a metal-contaminated soil than on the control soil, indicating a possible protective mechanism of sunflower mutants against oxidative stress caused by Cd and excess Zn.Heavy metals primarily increased the activity of antioxidant enzymes involved in the ascorbate–glutathione cycle in sunflower leaves. Activity of dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) was strongly increased in young seedlings exposed to heavy metals. The enzyme activities were even more pronounced in mutant lines. A significantly increased ascorbate peroxidase (APOX) activity in adult sunflowers exposed to heavy metals indicated an elevated use of ascorbate after a longer exposure to metal stress.An increased antioxidant level corresponded to a high Cd and Zn accumulation in young and adult sunflowers. Metal distribution, zinc translocation in particular, from the root into the shoot tissue obviously increased during sunflower growth and ripening. Altogether, these results suggest that sunflower plants, primarily the mutant lines, possess an efficient defence mechanism against oxidative stress caused by metal toxicity. A good tolerance of sunflowers toward heavy metals coupled with an increased metal accumulation capacity might contribute to an efficient removal of heavy metals from a polluted area.     

Comparative analysis of fatty acids,tocopherols and phytosterols content in sunflower cultivars (<i>Helianthus annuus</i>) from a three-year multi-local study

Sunflower oil is naturally rich in both unsaturated fatty acids and numerous minor components, with high levels of α-tocopherol and phytosterols that could play an important role in plant protection. These micronutriments, tocopherols and phytosterols, also exhibit health benefits for humans including reducing both cardiovascular diseases and aging disorders. α−Tocopherol represents more than 95% of total sunflower tocopherol and has the greatest vitaminic activity. Furthermore, this oil contains high amounts of β-sitosterol which is a promising health beneficial phytosterol. The objective of this study was to compare the content and composition of fatty acids, tocopherols and phytosterols in sunflower oil between different cultivars and locations in a three-year experiment, and to estimate the relationships between these minor components, fatty acids and climatic conditions. Results revealed that content and composition of these molecules are mainly determined by plant genotype. Nevertheless, the environmental conditions seemed to strongly influence the tocopherol content. The results suggest possible improvement in sunflower breeding for minor components.     

葵花籽油的酶辅助压榨制备工艺优化

葵花籽是一种优质的油料资源,是世界第四大油料作物。葵花籽不但含油量高,葵花籽油以其高达90%的不饱和脂肪酸和富含维生素E、胡萝卜素等营养成分的特点,被称为"保健油",有延缓衰老、调节新陈代谢和降低胆固醇等功能。采用酶辅助压榨法制备葵花籽油,在提高出油率的同时保留油脂的天然风味。通过单因素实验法研究了酶的种类、酶添加量、pH值、液固比、温度和时间对压榨葵花籽油出油率的影响,以确定最佳的工艺条件。结果表明,最佳工艺条件为：选用纤维素酶,酶添加量为0.7%,pH为4.5,液固比为25%,酶解温度为55℃,酶解时间为2.5 h。在此最佳条件下,出油率是传统冷榨法的3.48倍,油脂提取率达85%。     

Gene pathways associated with mitochondrial function,oxidative stress and telomere length are differentially expressed in the liver of rats fed lifelong on virgin olive,sunflower or fish oils

This study investigates the effect of lifelong intake of different fat sources rich in monounsaturated (virgin olive oil), n6 polyunsaturated (sunflower oil) or n3 polyunsaturated (fish oil) fatty acids in the aged liver. Male Wistar rats fed lifelong on diets differing in the fat source were killed at 6 and at 24 months of age. Liver histopathology, mitochondrial ultrastructure, biogenesis, oxidative stress, mitochondrial electron transport chain, relative telomere length and gene expression profiles were studied. Aging led to lipid accumulation in the liver. Virgin olive oil led to the lowest oxidation and ultrastructural alterations. Sunflower oil induced fibrosis, ultrastructural alterations and high oxidation. Fish oil intensified oxidation associated with age, lowered electron transport chain activity and enhanced the relative telomere length. Gene expression changes associated with age in animals fed virgin olive oil and fish oil were related mostly to mitochondrial function and oxidative stress pathways, followed by cell cycle and telomere length control. Sunflower oil avoided gene expression changes related to age. According to the results, virgin olive oil might be considered the dietary fat source that best preserves the liver during the aging process.     

Photosynthesis,chlorophyll fluorescence,inorganic ion and organic acid accumulations of sunflower in responses to salt and salt-alkaline mixed stress

Sunflowers were treated with mixing proportions of NaCl, Na₂SO₄, NaHCO₃, and Na₂CO₃. Effects of salt and saltalkaline mixed stress on growth, photosynthesis, chlorophyll fluorescence, and contents of inorganic ions and organic acids of sunflower were compared. The growth of sunflower decreased with increasing salinity. The contents of photosynthetic pigments did not decrease under salt stress, but their contents decreased sharply under salt-alkaline mixed stress. Net photosynthetic rates, stomatal conductance and intercellular CO₂ concentration decreased obviously, with greater reductions under salt-alkaline mixed stress than under salt one. Fluorescence parameters showed no significant differences under salt stress. However, maximal efficiency of PSII photochemistry, photochemical quenching coefficient, electron transport rate, and actual PSII efficiency significantly decreased but non-photochemical quenching increased substantially under salt-alkaline mixed stress. Under salt-alkaline mixed stress, sunflower leaves maintained a low Na⁺- and high K⁺ status; this may be an important feature of sunflower tolerance to salinity. Analysis of the mechanism of ion balance showed that K⁺ but not Na⁺ was the main inorganic cation in sunflower leaves. Our results indicated that the change in organic acid content was opposite to the change of Cl⁻, and the contribution of organic acid to total charge in sunflower leaves under both stresses decreased with increasing salinity. This may be a special adaptive response to stresses for sunflower. Sunflower under stress conditions mainly accumulated inorganic ions instead of synthesizing organic compounds to decrease cell water potential in order to save energy consumption.     

Screening of sunflower cultivars for metal phytoextraction in a contaminated field prior to mutagenesis

Sunflower can be used for the remediation of metal-contaminated soils. Its high biomass production makes this plant species interestingfor phytoextraction and using sunflower oil for a technical purpose may improve the economic balance of phytoremediation. The aim of the present field study was to screen 15 commercial cultivars of Helianthus annuus L. grown on metal-contaminated soil, to find out the variety with the highest metal extraction, which can be further improved by mutation or in vitro breeding procedures. Two different fertilizers (ammonium sulphate and ammonium nitrate) were also used to enhance the bioavailability of metals in soil Highly significant differences were observed within tested varieties for metal accumulation and extraction efficiency. Furthermore, ammonium nitrate increased cadmium extraction, whereas ammonium sulphate enhanced zinc and lead uptake in most tested cultivars. In this field-based sunflower screening, we found enhanced cumulative Cd, Zn, and Pb extraction efficiency by a factor 4.4 for Salut cultivar. We therefore emphasize that prior to any classical breeding or genetic engineering enhancing metal uptake potential, a careful screening of various genotypes should be done to select the cultivar with the naturally highest metal uptake and to start the genetic improvement with the best available plant material.