"植物细胞内pH调控系统"是适应环境逆境的一个耐性机制?

本研究把“植物细胞内pH调控系统”与植物抗逆性的关系作为研究对象,并探讨了参与植物细胞内pH调控相关的基因在碳酸盐(Na2CO3,NaHCO3)等逆境下的表达特性,其结果表明：NADP苹果酸酶(NADP—Malic Enzyme,NADP—ME)基因、磷酸烯醇式丙酮酸羧化酶(Phosphoenolpyruvate Carboxylase,PEP—Case)基因,还有细胞膜H^ —ATPase(plasmamembrane H^ —ATPase,p—H^ —ATPase)基因、液泡膜H^ —AT—Pase(vacuolar membrance H^ —ATPase,V—H^ —ATPase)基因、液泡膜H^ —PPase(vacuolar membrance H^ —PPase,V—H^ —Ppase)基因等的表达与NaCl逆境、碳酸盐逆境、外界环境pH逆境有应答关系,显示了这些基因在逆境下的表达有被强化的趋势。通过对逆境胁迫后植物根活体切片进行的pH变化趋势的观察,结果表明：植物根细胞在组织学水平上pH有明显的变化。在逆境下水稻根的组织学水平的观察,暗示了根组织有被酸性化的趋势,从而我们推测在逆境胁迫下细胞内pH发生了改变,不正常的细胞内pH会抑制细胞的生长发育,使植物受害。由此,我们提出细胞内pH调控系统是植物在长期的进化过程中获得的抗逆机制。在逆境下强化“细胞内pH调控系统”的调控能力能够提高植物的抗性。     

NaCl筛选法获得无标记耐盐转基因水稻的高效转化技术研究

NaCl筛选法是培养无标记耐盐转基因水稻的有效方法。以中华11、秀水11、春江06这3个粳稻品种成熟胚愈伤组织为材料,以SKC1为目标基因,研究NaCl筛选条件下,热激与液体共培养对农杆菌介导耐盐基因转化水稻效率的影响。结果显示,热激处理和液体共培养都能提高耐盐基因对水稻的转化率,其中,热激处理最高转化提高率达到46.2%,液体共培养后最高转化提高率达到60.7%。     

水稻线粒体ATP合成酶小亚基基因的鉴定及解析

本研究把碳酸盐(NaHCO3、NaCO3)对植物造成的逆境称为“碳酸盐逆境”(Carbonate stress)。从水稻根cDNA文库中筛选出一些与碳酸盐逆境相关的基因，水稻线粒体ATP合成酶6kDa亚基基因(简称：RMtATP6基因)为其中之一。该基因编码的氨基酸序列与Jansch等人(1996)从马铃薯(Solanum tuberosum)线粒体中纯化的线粒体ATP合成酶6kDa亚基氨基酸序列(F1F0-ATP合成酶的F0部分)具有同源性，但是这个小蛋白的功能尚不清楚，其基因也没有被鉴定。本研究克隆了这个基因(Accession number：AB055076)，并解析了在碳酸盐逆境胁迫下它的表达特性。RMtATP6基因编码的蛋白预测分子量为6．578kDa，预测的细胞内存在位置为线粒体膜间间隙，结果预示了RMtATP6基因编码的蛋白为水稻线粒体ATP合成酶6kDa亚基基因。Southern杂交结果表明RMtATP6基因是水稻核基因组中的一个单拷贝基因。通过对RMtATP6基因在植物中的表达特性及在碳酸盐逆境下在酵母中的功能解析，表明了该基因与碳酸盐逆境有关。     

NaCl对不同抗性水稻氮代谢及相关基因表达的影响

为了探究盐胁迫下不同抗性水稻氮代谢的变化,以抗性品种东稻4号、盐敏感品种日本晴为材料,测定NaCl胁迫下水稻根和叶中氮含量、氮代谢相关酶活及相关基因表达的变化。结果表明,0.3%的NaCl胁迫后水稻根和叶中NO~-_3含量、硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、依赖NADH的谷氨酸合酶(NADH-GOGAT)活性均有不同程度的下降,而NH~+_4含量、依赖Fd的谷氨酸合酶(Fd-GOGAT)、谷氨酸脱氢酶(GDH)、天冬氨酸转氨酶(AST)活性均升高,东稻4号氮含量及氮代谢酶活性比日本晴稳定,根和叶中变化一致。检测氮转运及代谢相关基因表达发现,硝酸根转运蛋白基因OsNRT1;1、OsNRT1;5、OsNRT1;8、OsNRT2;1,铵转运蛋白基因OsAMT1;1、OsAMT1;2及谷氨酰胺合成酶基因OsGS1;2、天冬氨酸转氨酶基因OsAS盐胁迫后在2个品种中均升高,在高表达部位升高显著;谷氨酸合酶基因OsFd-GOGAT在两品种叶中升高显著,根中稍有下降;谷氨酸合酶基因OsNADH-GOGAT和谷氨酸脱氢酶基因OsGDH在日本晴根中升高显著,在叶中及东稻4号中升高但不显著。OsNR1在NaCl胁迫后两品种叶中表达量显著降低,根中无差异。东稻4号OsNRTs及氮代谢相关基因表达量总体上高于日本晴,而日本晴OsAMTs升高幅度大于东稻4号。研究表明,NaCl胁迫下,东稻4号相比日本晴更能保持氮代谢稳定性,这可能是水稻抗性品种耐盐的一个重要机制。     

费尔干猪毛菜病程相关蛋白SfPR1a基因的异源表达增强了烟草对干旱、盐及叶斑病的抗性

为明确一年生草本盐生植物费尔干猪毛菜(Salsola ferganica Drob.)病程相关蛋白基因SfPR1a (GenBank登录号为JQ670917)是否参与了植物对逆境胁迫的响应,采用qRT-PCR检测了该基因在不同组织部位和脱落酸(ABA)、茉莉酸(JAs)、乙烯合成直接前体(ACC)等相关激素胁迫及NaCl处理下的表达规律,同时对转基因烟草在盐、旱及丁香假单胞菌等胁迫下的抗性进行了鉴定。结果显示, SfPR1a基因在费尔干猪毛菜根中的表达量显著高于茎叶中,且受到ABA、JAs、ACC、NaCl的积极诱导;干旱胁迫下,转基因烟草的丙二醛(MDA)含量显著低于野生型烟草,显示出较强的抗旱表型;盐胁迫下,异源表达SfPR1a的转基因烟草幼苗生长显著优于野生型烟草;丁香假单胞菌攻毒后的转基因烟草叶片呈现严重的坏死反应,但植株的整体抗性表型显著优于野生型烟草;亚细胞定位结果显示该蛋白定位于植物细胞质外体空间。以上结果表明,费尔干猪毛菜病程相关蛋白SfPR1a基因参与了植物对非生物及生物胁迫的抗性。     

盐胁迫下虎尾草上调基因的筛选和鉴定

虎尾草（Chloris virgata）是禾本科虎尾草亚族的一种一年生草本植物,适应性极强,能在恶劣的盐碱化土壤上生长。本实验构建了虎尾草的cDNA基因文库,随机挑选出2300个克隆,并且通过点杂交分析在NaCl胁迫下这些基因的表达情况。结果表明有59个基因在NaCl胁迫下强烈表达,这些上调基因中23个同时也被NaHCO3胁迫表达。这个结果暗示了NaCl逆境与NaHCO3逆境在基因表达的应答机制存在明显的差异。59个基因可以分成8类：能量代谢（21．70％）,信号转导（5．0％）,氧化逆境（13．30％）,光合作用（10．0％）,生长发育（5．5％）,转录因子（1．67％）,各种酶类00．0％）和一些未知基因（28．3％）。从中选出了一些上调基因进行Northern杂交分析,Northern杂交表明这些基因中的有些是在根或叶中表达,与点杂交的结果有一致的趋势。     

水稻线粒体ATP合成酶小亚基基因的鉴定及解析

本研究把碳酸盐(NaHCO3、Na2CO3)对植物造成的逆境称为“碳酸盐逆境“(Carbonate stress).从水稻根cDNA文库中筛选出一些与碳酸盐逆境相关的基因,水稻线粒体ATP合成酶6kDa亚基基因(简称:RMtATP6基因)为其中之一.该基因编码的氨基酸序列与Jansch等人(1996)从马铃薯(Solanum tuberosum)线粒体中纯化的线粒体ATP合成酶6kDa亚基氨基酸序列(F1F0-ATP合成酶的F0部分)具有同源性,但是这个小蛋白的功能尚不清楚,其基因也没有被鉴定.本研究克隆了这个基因(Accession number: AB055076),并解析了在碳酸盐逆境胁迫下它的表达特性.RMtATP6基因编码的蛋白预测分子量为6.578 kDa,预测的细胞内存在位置为线粒体膜间间隙,结果预示了RMtATP6基因编码的蛋白为水稻线粒体ATP合成酶6kDa亚基基因.Southern杂交结果表明RMtATP6基因是水稻核基因组中的一个单拷贝基因.通过对RMtATP6基因在植物中的表达特性及在碳酸盐逆境下在酵母中的功能解析,表明了该基因与碳酸盐逆境有关.     

不同种类盐胁迫对水稻种子萌发和幼苗生长的影响

采用水培法研究比较了 Na_2CO_3和NaHCO_3两种碱性盐,NaCl和Na_2SO_4两种中性盐和混合盐对水稻种子萌发和幼苗生长的影响。结果表明,盐碱处理下水稻种子的发芽率、发芽势、发芽指数、苗高、根长、侧根数和根系细胞质膜透性等均较CK极显著降低(P0.01)。其中,Na_2CO_3和NaHCO_3以及混合盐胁迫处理水稻种子的发芽指标和生长指标均极显著低于NaCl和Na_2SO_4处理(P0.01)。其中,以Na_2CO_3处理对水稻种子发芽的抑制作用最大,其发芽率仅8.0%,发芽势为0,发芽指数仅3.0。NaHCO3处理其次,发芽率为14.5%,发芽势为1.7%,发芽指数为6.9。Na_2CO_3和NaHCO_3以及混合盐胁迫处理水稻幼苗的苗高,主根长和侧根数等均极显著低于NaCl和Na_2SO_4处理(P0.01)。3个处理均无侧根萌发。不同种类盐处理水稻幼苗根系细胞质膜透性均极显著高于CK (P0.01),以Na_2CO_3细胞质膜透性最高,极显著高于其他盐处理(P0.01)。所有盐处理幼苗和根系K~+/Na~+比值均极显著低于CK(P0.01),其中Na_2CO_3、NaHCO_3和混合盐处理根系K~+/Na~+比值分别仅为0.05,0.07和0.13,均显著低于CK、NaCl和Na_2SO_4处理(P0.05)。可见,Na_2CO_3和NaHCO_3加重了伤害与其对水稻根系细胞膜的伤害和K~+吸收受到抑制有关。碱性盐主要通过影响水稻侧根萌发来影响水稻幼苗生长。     

NaHCO_3胁迫下星星草根特异表达蛋白初步鉴定

盐胁迫是影响全世界作物产量的主要非生物胁迫之一,东北松嫩平原的苏打盐碱土含有相对较高的碳酸盐（NaHCO3和Na2CO3）。与NaCl胁迫相比,碳酸盐胁迫对植物的影响具有更加复杂的特性,除Na^＋对植物的生长发育产生影响外,高pH也强烈抑制植物多种代谢过程。星星草是一种广泛分布于我国北方的天然耐盐碱植物,在含高Na＋和高pH值的土壤中能够生长良好,本文中,我们以星星草为实验材料,对NaHCO3与NaCl胁迫下星星草根蛋白质的双向电泳图谱进行了初步的比较与分析,以水（CK1）、NaCl（CK2）为对照,初步探查了NaHCO3胁迫特异诱导表达蛋白。实验结果表明,大部分蛋白质点在凝胶上的相对位置和丰度变化不明显,有7个蛋白质点与NaCl胁迫相比为NaHCO3胁迫特异诱导表达蛋白,5个点在两种盐胁迫下丰度均上调,但在NaHCO3胁迫下上调更明显。这些蛋白参与基因表达调控及能量代谢等过程。     

盐胁迫下转甜菜碱醛脱氢酶基因水稻幼苗耐盐生理的研究

在NaCl浓度0，3．0，5．0，7．0g／L下，对转甜菜碱醛脱氢酶(BADH)基因水稻的两个品系51—22，52—7及其受体亲本中花8号进行幼苗耐盐性试验。结果表明：转BADH基因水稻比其受体亲本耐盐性强，在高NaCl浓度(5．0，7．0g／L)胁迫下，甜菜碱醛脱氢酶基因可以提高盐胁迫下水稻幼苗过氧化氢酶(CAT)活性，提高根系活力和叶绿素含量，稳定细胞膜的透性，降低植株体内Na^ 的积累，从而减轻幼苗受盐害的程度。盐胁迫下水稻幼苗的CAT活性、SNa^ ／K^ 、叶Na^ ／K^ 、叶绿素含量是影响幼苗生长的主要生理指标。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...