水稻耐亚铁毒QTLs的定位

亚铁毒是潜育性水稻土中限制水稻产量的主要因子。利用龙杂8503／IR64的F2和等价的F3群体,在营养液中培养来定位耐亚铁毒的QTLs。通过构建101SSR标记的遗传连锁图谱来确定耐亚铁毒QTLs的位置和特性。借助叶片棕色斑点指数、株高和最大根长3个性状,利用营养液在水稻苗期来评价F2单株、F3群体和亲本龙杂8503、IR64,共检测到叶片棕色斑点指数、株高和最大根长的QTLs20个,分布在水稻的10条染色体上,表明这些性状受多基因控制。控制叶片棕色斑点指数的QTLs分别定位在第1染色体的RM315-RM212、第2染色体的RM6-RM240和第4染色体的RM252-RM451之间。与前人的研究结果比较发现：1）位于第4染色体RM252-RM451之间的控制叶片棕色斑点指数的QTL与水稻功能图谱上控制叶绿素含量减少的QTL的位置一致。另一个位于第1染色体的RM315-RM212之间的控制叶片棕色斑点指数的QTL与水稻功能图谱上位于C178-R2635之间控制叶绿素含量的QTL连锁。2）位于第2染色体RM6-RM240之间的第3个控制叶片棕色斑点指数的QTL与位于RZ58-CD0686的控制钾吸收的QTL连锁。     

水稻铁害和应激乙烯释放的关系

在热带地区的水稻栽培中,常遇到水稻青铜病（ｂｒｏｎｚｉｎｇ）的危害．已知它是由水田中高浓度的亚铁离子所引起,故又叫铁害．但至今没有可靠的生理诊断指标用于抗性品种的筛选．本文研究了铁害与应激乙烯释放的关系,试图以应激乙烯的释放作为铁害的生理诊断指标．试验用两种方法模拟水稻致病．第一种方法是将水稻离体叶片的剪口端浸入ＦｅＳＯ４溶液中,靠叶片蒸腾作用吸收Ｆｅ＋＋而致病．另一种方法是在水培培养液中加入ＦｅＳＯ４通过水稻根系吸收Ｆｅ＋＋而致病．研究结果表明,当处理离体叶片时,发病强度和应激乙烯释放量呈显著相关,但叶片内铁含量的增加与发病强度和应激乙烯释放都没有相关性．而处理完全植株时,叶片中乙烯释放几乎不受影响．当部分或全部切除根时,叶片中乙烯释放则可被亚铁离子激发。表明水稻根系限制了Ｆｅ＋＋的吸收速率,而Ｆｅ＋＋进入叶组织的速率又决定应激乙烯的释放和组织的伤害程度．因此,叶片应激乙烯的释放作为铁害的生理诊断指标只有在当根系受到某种伤害时才可能适用,譬如移栽和毒性土壤等因素造成的根系的伤害．     

外源钾对铁胁迫下水稻细胞壁多糖含量及耐铁性的影响

以耐铁毒型水稻品种协优9308和铁毒敏感型水稻品种Ⅱ优838为实验材料,采用溶液培养法研究250mg.L-1Fe2+(EDTA-Fe2+)胁迫下,不同钾水平对两种水稻的生长特性、酸性磷酸酶(APA)、果胶甲酯酶(PME)、根系果胶含量、半纤维素1含量以及半纤维素2含量的影响。结果表明,经250mg.L-1Fe2+处理7d和14d后,协优9308和Ⅱ优838的相对根长明显下降,APA、PME的活性显著升高,果胶含量、半纤维素1含量、半纤维素2含量显著增加,Ⅱ优838酶活性及细胞壁多糖含量提高幅度较大,表现出其铁毒敏感性,并且随着处理时间的延长,铁胁迫对两种水稻相对根长,PME活性,HC1含量及HC2含量的影响越显著,但APA活性和果胶含量则没有明显变化。加入外源钾可以不同程度的降低酶活性及细胞壁多糖含量,外源钾浓度为200mg.L-1,对水稻相对根长,APA活性,HC1含量缓解效果较好;外源钾浓度为400mg.L-1,对PME活性,果胶含量缓解效果较好。随着外源钾浓度升高,水稻铁毒症状得到不同程度的缓解,但钾浓度高于200mg.L-1又会对水稻造成新的胁迫。由此推测,水稻通过提高根系细胞壁多糖含量来增加根尖铁的结合位点,以及细胞壁的厚度和刚性,并降低细胞壁的伸展性,使根细胞的伸长受抑,从而提高其铁耐性。     

不同pH值下丛枝菌根真菌对枳生长及铁吸收的影响

摘要：【目的】本文对营养液不同pH值下丛枝菌根(arbuscular mycorrhiza)真菌地表球囊霉（Glomus versiforme）对枳[Poncirus trifoliata]实生苗生长及植株铁营养状况的影响进行了初步研究。【方法】采用盆栽砂培试验,分别施浇pH 5.0、6.0、7.0和8.0的霍格兰营养液（含50 μM Fe-EDTA）;常规方法测定植株生长指标;曲利苯蓝染色法测定菌根侵染率;分光光度法测定叶绿素含量和根系三价铁螯合物还原酶活性;原子吸收分光光度法测定叶片钾和活性铁含量;钒     

花粉管通道法介导的真菌耐盐基因转化拟南芥

橡胶树内生真菌ITBB2-1具有很强的抗盐性,在培养基中添加2倍海水盐度的NaCl能显著促进菌落的生长.采用两种方法研究利用花粉管通道法将ITBB2-1耐盐基因导入拟南芥.多数耐盐转基因植株畸形,生长发育不正常.通过对一千两百余株转基因植株的筛选,获得了耐盐性显著提高、生长发育正常的转基因植株3个.对主要农艺性状统计分析发现,转基因植株叶片的长度、宽度和面积均比野生型植株小,差异达极显著水平.转基因植株SR3的角果长度仅为野生型的64.5%,SR1和SR2的角果长度与野生型无显著差异.本研究表明,在真菌耐盐机制尚未得到研究和耐盐基因尚毒克隆的情况下,可以采用花粉管通道法将其耐盐特性导入高等植物中.     

苹果铁结合蛋白基因（＊＊Apf1）的克隆和序列分析

铁结合蛋白是一种广泛存在于动物、植物和微生物中的铁储藏蛋白,是动、植物生长发育使用的储存铁的唯一共同来源.该蛋白在植物体中的主要功能是在种子形成、叶片衰老或环境中铁过量时积累,在种子萌发或质体绿化过程中释放铁,从而调节植物对铁的吸收和释放[1,2].同时,该蛋白也是解决全球动物和人类饮食缺铁有效的方法[3].转基因研究证明大豆铁结合蛋白基因能提高水稻种子中铁结合蛋白的的含量[4].同时在转基因烟草植株后代中由于叶片中积累了铁结合蛋白而对病毒引起的坏死和真菌的感染表现出耐性,对因各种环境胁迫而导致的细胞氧化性损伤有保护作用[5].铁结合蛋白基因是植物体内唯一依赖于铁而进行表达的基因[6].     

转基因水稻胚乳中表达铁结合蛋白提高稻米铁含量

为提高我国稻米的铁含量,通过农杆菌介导将自行克隆的菜豆(Phaseolus limensis)铁结合蛋白(Ferritin)基因导入了一个高产粳稻(Oryaz sativa L.ssp．japonuica)品种中,获得17个独立的转基因水稻株系。分子检测证明,外源基因在多数转基因水稻植株基因组中有1～3个整合位点,并可稳定遗传。在水稻种子贮存蛋白谷蛋白基因GluB-1启动子的控制下,铁结合蛋白基因可在转基因水稻的种子中高效特异地表达,不同转化子中的表达量有明显不同。在转基因水稻种子中表达铁结合蛋白后对提高精米中的铁含量有明显的效果,相对于未转化对照最多可提高64％,而锌的含量并无明显变化。     

椪柑叶片元素含量与产量关系的探讨

柑桔营养诊断指标的确定,通常要考虑到植株的产量因素,然而,由于树体营养状况受诸多内外因子的影响,因而也就增加了营养诊断指标与产量之间关系的复杂性。在探讨柑桔叶片元素含量与产量的关系时,研究者^[1-4]基于不同试验条件(包括采样),常常得出不同的结果和见解。因此,深入阐明柑桔叶片元素水平与产量间的关系,对营养诊断的研究具有重要意义。近年来,作者在研究椪柑(Citrus reticulata Blanco)营养诊断指标的同时,探明了叶片氮、磷、钾、钙、镁含量与植株产量的相互关系。     

水稻耐盐/碱性鉴定评价方法

土壤盐/碱化是盐/碱稻作区水稻生产稳定发展的主要限制因素.为了提高水稻耐盐/碱性,扩大水稻种植面积,减轻盐/碱胁迫导致的水稻减产,许多学者广泛开展了水稻耐盐/碱性的基因型差异、生理生化、遗传及定位等研究,并取得了显著成绩.但国内在耐盐/碱性鉴定评价方法方面还缺乏统一标准,这影响着水稻耐盐/碱性研究的深入开展.本文阐述了国内外至今所采用的水稻耐盐/碱性鉴定方法、耐盐/碱指标和分级标准等,以期为我国水稻耐盐/碱性鉴定评价技术规范的制定以及水稻耐盐/碱性种质资源鉴定、生理生化分析和遗传育种提供参考依据.     

沿黄地区盐碱地种植水稻土壤理化性质的比较

土壤盐碱化是一个世界性的问题,中国盐渍土面积为3. 47×105 km2(不包括滨海滩涂) [1]. 陕西省沿黄地区分布有大面积盐碱地,该地区土地利用率极低. 盐碱地治理通常采用水利工程、化学改良和生物改良等措施[2-4] ,植物改良技术因具有费用少、见效快以及在改善大面积盐碱土的同时能获得经济效益等优点而受到广泛关注. 已有的在盐碱地区种植水稻(Oryza sativa Linn.)的研究集中在不同改良剂对盐碱地的改良效果及对水稻产量的影响,盐分胁迫对水稻生长的影响以及作物收获还田后对盐碱地的改良等方面[5-7]. Hussain等[8]研究了水稻在盐碱地的耐盐机制;罗新正等[9]认为,连续多年采用种稻模式进行单纯性洗排盐碱可明显降低松嫩平原盐碱地表层土壤的含盐量.     

Impact of salicylic acid on the antioxidant enzyme system and hydrogen peroxide production in Cucumis sativus under chilling stress

Salicylic acid (SA) is a naturally produced compound and has been implicated to play important roles in defense of plants against diverse biotic and abiotic stresses. To understand how SA functions in the tolerance of cucumber (Cucumis sativus) to chilling stress, endogenous SA levels in two different cultivars with opposite chilling responsiveness were quantified. Membrane integrity, including malondialdehyde (MDA) content and leakage of electrolyte, was also examined in SA-pretreated cucumber plants under chilling conditions. In addition, activities of the two antioxidant enzymes peroxidase (POD) and catalase (CAT) were quantified, and hydrogen peroxide (H2O2) production was investigated histochemically in SA-treated leaves under chilling temperature. Chilling stress resulted in greater induction of SA levels in the chilling-tolerant cultivar Changchun mici in both leaves and seeds compared to the chilling-sensitive one Beijing jietou, while the former one contained higher levels of SA than the latter one in the seeds under normal conditions. Pretreatment with SA diminished the increased electrolyte leakage and MDA content caused by chilling in the leaves of both cultivars, while much less MDA and electrolyte leakage were produced in Changchun mici compared to Beijing jietou. Moreover, exogenous application of SA increased significantly the POD and CAT activities and soluble protein content. Most importantly, exogenous SA treatment could eliminate the accumulation of H202 in leaves and cotyledons of both cultivars caused by chilling stress. The data clearly demonstrated that the chilling-tolerant cultivar displays a higher SA level than the chilling-sensitive one, and that exogenous SA can enhance the chilling tolerance ability, which might be achieved through modulating the antioxidant system in cucumber.     

Response of sun- and shade-adapted plants of Haberlea rhodopensis to desiccation

The differences in some morphological and physiological characteristics of sun- and shade-adapted Haberlea rhodopensis plants were compared. Changes in the photosynthetic activity, electrolyte leakage from leaf tissues, malondialdehyde content (MDA) and leaf anatomy were studied at different degrees of desiccation as well as after rehydration of plants. The MDA content in well-watered sun Haberlea plants was higher compared to shade plants suggesting higher lipid peroxidation, which is commonly regarded as an indicator of oxidative stress, but desiccation of plants at high light did not cause additional oxidative damage as judged by the unaffected MDA content. The electrolyte leakage from dried leaves (8% RWC) from both shade and sun plants increased fourfold indicating similar membrane damage. However, the recovery after rehydration showed that this damage was reversible. Well-watered sun plants had higher photosynthetic activity probably due to the larger thickness of the mesophyll layer in such plants. On the other hand, desiccation at high light reduced CO₂ assimilation which was in accordance with the stronger reduction of stomatal conductance. Stomata were visible only on the abaxial side of sun leaves having also higher abundance of non-glandular trichomes. Increased trichomes density and epicuticular waxes and filaments upon desiccation could help plants to increase reflection, reduce net radiation income, slow down the rate of water loss and survive adverse conditions.     

外源GSH对盐胁迫下番茄幼苗生长及抗逆生理指标的影响

采用营养液栽培法,研究外源谷胱甘肽(GSH)对NaCl胁迫下番茄幼苗生长、根系活力、电解质渗透率和丙二醛(MDA)、脯氨酸(Pro)、可溶性糖含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的影响,为利用外源物质减轻盐胁迫伤害提供理论依据。结果显示:(1)NaCl胁迫显著抑制了番茄幼苗的生长、根系活力和SOD、POD、CAT活性,提高了电解质渗透率及MDA、Pro、可溶性糖含量;(2)外源喷施GSH能够诱导NaCl胁迫下番茄幼苗叶片抗氧化酶SOD、POD、CAT活性上调,电解质渗透率及MDA含量下降,Pro和可溶性糖含量恢复至对照水平;(3)外源喷施还原型谷胱甘肽抑制剂(BSO)使NaCl胁迫下番茄幼苗的根系活力以及抗氧化酶SOD、POD、CAT活性下降,脯氨酸含量提高;(4)喷施GSH可诱导BSO和NaCl共处理番茄植株的根系活力、SOD、POD、CAT活性提高,MDA和Pro含量降低。研究表明,外源GSH可通过提高促进盐胁迫下番茄幼苗植株渗透调节能力及清除活性氧的酶促系统的防御能力、降低细胞膜脂过氧化程度、保护膜结构的完整性,从而有效缓解NaCl胁迫对番茄幼苗生长的抑制,提高其耐盐性。     

拟南芥AtUNE12基因的耐盐功能初探

bHLH转录因子家族成员在植物生长发育、生理代谢及非生物胁迫响应过程中起重要作用。本研究选取拟南芥抗逆相关bHLH转录因子家族中AtUNE12基因为研究对象,对其进行耐盐功能初探。首先构建AtUNE12基因的植物过表达载体（pROKⅡ-AtUNE12）,通过农杆菌介导的浸花法转化拟南芥,利用qRT-PCR技术检测获得T₃代AtUNE12过表达转基因植株。在盐胁迫下,分析过表达AtUNE12与野生型拟南芥长势、根长及鲜重;比较过表达AtUNE12与野生型植株的电解质渗透率、失水率、MDA含量、POD与SOD活性及H₂O₂含量,鉴定AtUNE12基因是否具有耐盐能力。结果表明：过表达AtUNE12基因降低了拟南芥植株的失水率、电解质渗透率及MDA含量,保护细胞膜结构的完整性;增强了POD与SOD活性,降低了拟南芥植株内的H₂O₂含量,进而增强拟南芥植株的ROS清除能力,从而提高拟南芥的耐盐能力。     

Overexpression of TaLEA Gene from Tamarix androssowii Improves Salt and Drought Tolerance in Transgenic Poplar (Populus simonii × P. nigra)

Late embryogenesis abundant (LEA) genes were confirmed to confer resistance to drought and water deficiency. An LEA gene from Tamarix androssowii (named TaLEA) was transformed into Xiaohei poplar ( Populus simonii × P. nigra) via Agrobacterium . Twenty-five independent transgenic lines were obtained that were resistant to kanamycin, and 11 transgenic lines were randomly selected for further analysis. The polymerase chain reaction (PCR) and ribonucleic acid (RNA) gel blot indicated that the TaLEA gene had been integrated into the poplar genome. The height growth rate, malondialdehyde (MDA) content, relative electrolyte leakage and damages due to salt or drought to transgenic and non-transgenic plants were compared under salt and drought stress conditions. The results showed that the constitutive expression of the TaLEA gene in transgenic poplars could induce an increase in height growth rate and a decrease in number and severity of wilted leaves under the salt and drought stresses. The MDA content and relative electrolyte leakage in transgenic lines under salt and drought stresses were significantly lower compared to those in non-transgenic plants, indicating that the TaLEA gene may enhance salt and drought tolerance by protecting cell membranes from damage. Moreover, amongst the lines analyzed for stress tolerance, the transgenic line 11 (T11) showed the highest tolerance levels under both salinity and drought stress conditions. These results indicated that the TaLEA gene could be a salt and drought tolerance candidate gene and could confer a broad spectrum of tolerance under abiotic stresses in poplars.     

Oxidative damages induced by short-term exposure to cadmium in bean plants: Protective role of salicylic acid

The role of salicylic acid (SA) in alleviating cadmium (Cd) toxicity was investigated in a hydroponic cultivation system. Short-term exposure of bean (Phaseolus vulgaris) plants to 20 μM Cd inhibited biomass production and intensively increased accumulation of Cd in both roots and leaves. At leaf level, Cd significantly decreased mineral ions, chlorophyll and carotenoids concentrations. Concomitantly, Cd enhanced electrolyte leakage, H₂O₂ content and lipid peroxidation as indicated by malondialdehyde (MDA) accumulation. SA pretreatment decreased the uptake and the transport of Cd, alleviated the Cd-induced inhibition of nutrient absorption and led to a significant increase of chlorophyll and carotenoid content. SA application alleviated the oxidative damages as evidenced by the lowered H₂O₂ and MDA content. SA particularly induced an increase in both CAT and APX activities accompanied by a significant reduction in SOD and POD activities. As important antioxidants, ascorbate and glutathione contents in bean leaves exposed to cadmium were significantly decreased by SA treatment. These results reveal the potentiating effect of salicylic acid in regulating cadmium induced oxidative stress in bean plants.     

Iron nutrition affects cadmium accumulation and toxicity in rice plants

The effect of iron (Fe) nutrition on cadmium (Cd) toxicity and accumulation in rice plants was studied using a hydroponic system. The inhibitory effect of Cd on plant growth and chlorophyll content (SPAD value) was dependent on Fe level and the genotype. Malondialdehyde (MDA) content in leaves and roots was not much affected by an increased Cd stress at 0.171 mg l⁻¹ Fe, but it showed a rapid increase when the plants were exposed to moderate (1.89 mg l⁻¹) and high (16.8 mg l⁻¹) Fe levels. High Fe nutrition caused a marked reduction in Cd content in both leaves and roots. Fe content in plants was lower at high Cd (5.0 μM) stress than at low Cd (<1.0 μM) stress. Cd stress increased both superoxide dismutase (SOD) and peroxidase (POD) activities at low and moderate Fe levels. However, with high Fe level, it increased the POD activity, but reduced the SOD activity. Our results substantiate the hypothesis that cell membrane-bound iron transporter (carrier) involved in high-affinity iron transport systems can also transport Cd, and both these ions may compete for this common carrier. The study further showed that there were significant correlations between MDA and Fe contents in leaves and roots of rice plants. It is suggested that the occurrence of oxidative stress in plants exposed to Cd stress is mediated by Fe nutrition. The present results also show that Cd stress affects the uptake of Cu and Zn.     

玉米胚发育过程中脱水耐性的变化

对离体玉米胚脱水耐性的变化以及不同脱水速率对其脱水耐性的影响进行了研究。授粉后16d的玉米胚能耐轻微脱水,含水量从1.45降低到0.28gH2Og-1DW时胚的萌发率为100%,但含水量低于0.1gH2Og-1DW时胚死亡。胚的脱水耐性随着发育逐渐加强,表现为电解质渗漏速率逐渐降低,萌发率和幼苗干重逐渐增加。授粉后20d胚内超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性较高,过氧化氢酶(CAT)活性较低;授粉后24d,这些酶的活性与授粉后20d的正好相反。脂质过氧化产物丙二醛(MDA)在种子发育过程中呈下降趋势。不同脱水速率明显地影响胚的脱水耐性:在慢速脱水到含水量0.1~0.18gH2Og-1DW时,胚的萌发率和幼苗干重比快速脱水高,电解质渗漏速率比快速脱水低;在快速脱水条件下胚中的SOD、APX活性和MDA含量也比慢速脱水高;CAT活性的变化不明显。     

Enhancement of low-temperature tolerance in transgenic tomato plants overexpressing Lefad7 through regulation of trienoic fatty acids

We studied how tomato (Lycopersicon esculentum Mill.) chloroplast omega-3 fatty acid desaturase gene (Lefad7) overexpression enhanced low-temperature (LT) tolerance in transgenic tomato plants. In these plants, the content of linolenic acid (18:3) markedly increased and, correspondingly, the content of linoleic acid (18:2) decreased. Similar changes were found after 6 h under LT (4°C) treatment. Under LT stress, wild type (WT) tomato plants showed a much greater increase in relative electrolyte leakage and malondialdehyde (MDA) contents compared with transgenic plants. Transgenic plants exhibited higher activities of antioxidative enzymes and a lower content of reactive oxygen species (ROS). Transgenic plants maintained a relatively higher level of the net photosynthetic rate (P _N) and chlorophyll (Chl) content than WT plants under LT stress. Taken together, we suggested that overexpression of Lefad7 enhanced LT tolerance by changing the composition of membrane lipids in tomato plants, with the increased content of trienoic fatty acids and reduced content of dienoic fatty acids that led to series of physiological alterations.