转甜菜碱醛脱氢酶(BADH)基因小麦的耐盐耐旱性

采用室内模拟盐、旱胁迫，结合田间实际测定的方法，对基因枪法获得的转BADH基因小麦多个株系的不同世代材料进行了耐盐、耐旱性鉴定。结果表明，在旱、盐胁迫条件下，转BADH基因小麦在种子萌发、幼苗生长、根系发育以及质膜保护等方面均比受体品种（对照）具有明显的优势；在田间生长条件下的转基因株系，其叶片蒸腾强度比对照明显降低，而离体叶片失水速率与对照没有明显差别。     

转甜菜碱醛脱氢酶基因提高烟草抗旱及耐盐性

将甜菜碱醛脱氢酶（BADH）基因与组成型启动子CaMV 35S启动子融合,构建了植物表达质粒pBIBB。通过根癌农杆菌介导将BADH基因导入烟草,经PCR、Southern杂交、Northern杂交证明BADH基因已整合到烟草基因组中并在转基因植株中转录和表达。测定转基因植株叶片中甜菜碱醛脱氢酶活性,结果显示对照植株没有BADH酶活性,转基因植株的各个株系间甜菜碱醛脱氢酶比活力差异较大,范围在0.1~1.0 U mg-1间。转BADH基因的烟草在盐胁迫和聚乙二醇（PEG）胁迫条件下生长状态良好,生长势强于未转基因植株,说明BADH基因能在异源植物中正常翻译、表达和用于植物抗旱、耐盐基因工程的研究。     

通过基因枪和农杆菌介导用BADH基因转化小麦

土壤盐碱是一种严重障碍作物生产的环境因子,甜菜碱醛脱氢酶BADH基因是一种重要的可赋予植物渗透调节抗性的基因。本研究用基因枪法及农杆菌介导法向小麦幼胚和成熟胚愈伤组织导入了BADH基因。用PDS-1000／HE基因枪轰击2933块幼胚愈伤组织,分化出了45株再生植株,分化率为1．53％。PCR分析表明,其中的5株为BADH基因转化植株。用PPT涂抹其叶片,进一步证实了PCR的结果。以小麦成熟胚愈伤组织为受体,用农杆菌介导转化1968块愈伤,仅再生出了5株绿苗,PCR检测结果均为阴性。但对其转化愈伤组织的PCR检测表明,外源基因已在受体细胞中实现了整合。以幼胚愈伤组织为受体,用农杆菌介导转化2933块愈伤,共再生出了21株绿苗。对其进行PCR检测,仅有5株为BADH基因转化植株。转化处理过的幼胚愈伤组织的绿苗再生率（0．72％）高于成熟胚愈伤（0．25％）。与对照相比,所有的转化植株均能够在0．5％NaCl（w／w）条件下正常生长,表明外源BADH基因已经整合并表达。     

抗旱基因在小麦抗旱基因工程中的应用进展

干旱严重影响小麦的生长发育及产量,小麦抗旱育种是保障小麦生产的重要措施,利用基因工程技术提高小麦抗旱性是优于传统育种的有效途径。抗旱基因主要包括调节基因（蛋白激酶、蛋白酶和转录因子基因）和功能基因。目前,已证实的可提高小麦抗旱性的基因主要为转录因子基因CBF/DREB1、MYB、NAC（NAM、ATAF1、ATAF2和CUC2）、HD-Zip和WRKY等和功能基因LEA蛋白基因、甜菜碱合成酶基因和海藻糖合成酶基因等。本文从转录因子基因和功能基因2个方面概述国内外利用基因工程技术提高小麦抗旱性的研究进展,并对目前存在的问题进行分析,以期为小麦抗旱遗传改良及育种提供参考。     

冬小麦抗旱性与膜脂过氧化的关系及其氮素调控机理

在大田试验条件下,测定了两个不同抗旱性小麦品种郑麦9023（水地品种,抗旱性差）和长武134（旱地品种,抗旱性强）在不同施氮量条件下拔节期叶片MDA、H2O2含量以及SOD、CAT活性的变化。结果表明,抗旱性和小麦叶片的保护酶活性和膜质伤害物质的含量密切相关,而且受氮素营养的调控。抗旱品种相对不抗旱品种具有较高的SOD和CAT活性,而MDA和H2O2较低;MDA和H2O2含量随施氮量的增加呈现先降后升的趋势,而SOD和CAT则呈相反的变化趋势。     

水分胁迫对不同小麦品种幼苗生理特性的影响

本文以4个抗旱性不同的小麦品种豫麦34、郑州9023、洛旱2号、洛旱6号为试验材料,在20%的PEG6000（w/v）渗透胁迫下,研究了不同小麦品种幼苗期的细胞膜相对透性、相对含水量、可溶性糖及可溶性蛋白含量的变化。结果表明：在20%的PEG6000（w/v）渗透胁迫下,四个小麦品种幼苗叶片相对含水量均下降;细胞膜相对透性、可溶性糖含量均上升,且与抗旱性表现一致;而可溶性蛋白含量的变化趋势同抗旱性表现不一致。由此说明,细胞膜相对透性、相对含水量及可溶性糖含量的变化可作为小麦苗期可靠的抗旱性鉴定指标,而可溶性蛋白在小麦苗期抗旱性中的作用还需要进一步研究。     

转甜菜碱醛脱氢酶基因马铃薯的抗旱耐盐性

通过根癌农杆菌介导法将甜菜碱醛脱氢酶(BADH)基因导入马铃薯栽培品种甘农薯2号, 经PCR、Southern杂交和Northern杂交证明BADH基因已整合到马铃薯基因组中并在转基因植株中转录和表达。测定表明对照植株没有BADH酶活性, 各转化株系在胁迫前后BADH酶活性近似, 在2~11 U之间。BADH酶活性与叶片的相对电导率呈一定的负相关(y= –3.7738x+57.083, r=0.989^**)。在NaCl和PEG胁迫下, 转基因植株生长正常, 株高比对照提高0.41~1.00 cm, 单株重量比对照增加10%~35%, 说明外源BADH基因的导入提高了马铃薯植株对干旱和盐碱的抗性。     

转甜菜碱醛脱氢酶基因马铃薯的抗旱耐盐性

通过根癌农杆菌介导法将甜菜碱醛脱氢酶(BADH)基因导入马铃薯栽培品种甘农薯2号, 经PCR、Southern杂交和Northern杂交证明BADH基因已整合到马铃薯基因组中并在转基因植株中转录和表达。测定表明对照植株没有BADH酶活性, 各转化株系在胁迫前后BADH酶活性近似, 在2~11 U之间。BADH酶活性与叶片的相对电导率呈一定的负相关(y= –3.7738x+57.083, r=0.989^**)。在NaCl和PEG胁迫下, 转基因植株生长正常, 株高比对照提高0.41~1.00 cm, 单株重量比对照增加10%~35%, 说明外源BADH基因的导入提高了马铃薯植株对干旱和盐碱的抗性。     

外源甜菜碱醛脱氢酶(BADH)基因对小麦合成甜菜碱的影响

通过毛细管电泳,对转入山菠菜BADH基因的小麦品系T1,T4,T6及受体石4185的甜菜碱含量进行了检测,发现在胁迫与未胁迫条件下,T1,T4,T6的甜菜碱含量均高于受体石4185,T1,T6与受体差异显著,T4与受体差异不显著.说明外源BADH基因可提高小麦中甜菜碱含量,但在不同品系中的表达有一定差异.     

抗旱转基因小麦的研究进展

受气候复杂多变的影响，小麦生长期间干旱胁迫成为影响其产量的主要因素之一，利用基因工程技术提高小麦抗旱性非常必要。目前，已鉴定出一部分与小麦抗旱性相关并可以提高产量的基因，但与水稻、玉米和其他粮食作物相比，对抗旱转基因小麦的开发研究较少。文章重点关注小麦耐旱性的评价标准以及转基因小麦品种在提高抗旱性方面的进展，讨论了当前在转基因小麦方面取得的一些成就和发展中存在的问题，以期为小麦抗旱性基因工程育种提供理论依据。     

变水处理条件下小麦幼苗的甜菜碱代谢与抗旱性的关系

在缓慢土壤水分胁迫一复水的变水处理条件下,小麦幼苗地上部分相对含水量在80%~70%时,甜菜碱含量及甜菜碱醛脱氢酶活性最高,相对含水量大于80%或小于70%,甜菜碱的含量和甜菜碱醛脱氢酶活性都降低,并且两者变化是“同步”的。水分胁迫时,小麦幼苗迅速积累甜菜碱,抗旱型小麦增加6~8倍,水分敏感型增加4倍。积累甜菜碱与     

Sucrose Accumulation in Sugar Beet Under Drought Stress

Drought stress may affect sucrose accumulation of sugar beet by restricting leaf development and storage root growth. The objective of this study was to identify changes occurring in the storage root of Beta beets in growth characteristics and ions and compatible solutes accumulation under drought with regard to sucrose accumulation. Two pot experiments were conducted: (1) sugar beet well supplied with water (100 % water capacity), under continuous moderate (50 %) and severe drought stress (30 %), (2) sugar beet and fodder beet well supplied with water (100 %) and under continuous severe drought stress (30 %). Under drought stress, the ratio of storage root to leaf dry matter of sugar beet decreased indicating a different partitioning of the assimilates. The sucrose concentration of the storage root was reduced. In the root, the number of cambium rings was only slightly affected, although drought stress was implemented already 6 weeks after sowing. In contrast, the distance between adjacent rings and the cell size was considerably restricted, which points to a reduced expansion of existing sink tissues. The daily rate of sucrose accumulation in the root showed a maximum between 16 and 20 weeks after sowing in well‐watered plants, but it was considerably reduced under drought stress. The concentration of compatible solutes (K, Na, amino acids, glycine betaine, glucose and fructose) decreased during growth, while it was enhanced because of drought. However, when sucrose concentration was added, a constant sum of all examined solutes was found throughout the vegetation period. It was similar in sugar beet and in fodder beet despite different concentrations of single solutes, and the total sum was not affected by water supply. A close negative relationship between the concentration of compatible solutes and sucrose occurred. It is therefore concluded that the accumulation of compatible solutes in the storage root of Beta beets under drought might be a physiological constraint limiting sucrose accumulation.     

甜菜碱的研究进展及其在烟草中应用前景分析

在外界干旱、低温、盐等逆境胁迫的情况下,某些植物能自身合成甜菜碱有效减轻植物受到的伤害。对于自身不能合成甜菜碱的植物,可以通过基因工程法或外源施入法促进体内甜菜碱的积累,从而达到同样的缓解伤害效应。笔者概述了甜菜碱的发现、生物合成途径、在植物中的应用研究进展,同时对甜菜碱在烟草作物上的研究现状、存在问题和应用前景进行了可行性评价分析,认为甜菜碱具有成本低、用量少、抗逆性强等特点,在烟草种植中已经具备了推广应用的潜力。     

外源甜菜碱对PEG胁迫下小桐子种子萌发和幼苗生长的保护作用

外源甜菜碱对小桐子种子和幼苗分别进行浸种和灌根处理,结果表明,外源甜菜碱浸种可提高小桐子种子在PEG胁迫下的发芽率和改善幼苗的生长状况.外源甜菜碱浸种和灌根,可提高幼苗在PEG胁迫下的存活率.此外,PEG胁迫可提高小桐子幼苗中的内源甜菜碱含量.结果表明,外源甜菜碱处理不仅可提高小桐子种子在PEG胁迫下的发芽率,而且可提高幼苗对PEG胁迫的抵抗能力.     

外源甜菜碱对盐胁迫下大麦幼苗体内多胺和离子含量的影响

外源甜菜碱对200 mmol/L NaCl胁迫下大麦幼苗的伤害有显著的缓解效应,0.5～10.0 mmol/L的甜菜碱均可以有效抑制盐胁迫导致的叶片中MDA含量的上升,增加根系含水量与幼苗鲜重,降低植株体内Na+/K+比,尤以1 mmol/L甜菜碱的效应最明显。甜菜碱可以显著地提高盐胁迫下大麦幼苗根系多胺含量,促进叶片内腐胺与亚精胺向精胺的转化     

Synthesis of Osmotically Active Substances in Winter Wheat Leaves as Related to Drought Resistance of Different Genotypes1)

Water stress increased mono-saccharides and decreased di-saccharides concentration in four field grown genotypes, regardless of their different drought susceptibility. Sandy, a USA genotype known for giving satisfying yields in droughty environments, outstood the other cultivars in terms of betaine and proline concentration in leaf tissues; these aminoacids are therefore considered responsible for the most negative Ψs perceived in this cultivar. PV-curve technique revealed for Tullio, the drought susceptible Italian genotype, an osmotic adjustment of –0.63 MPa, four times greater than in Pandas, though this drought resistant cultivar showed a similar content in osmotically active substances; the authors therefore hypothesize an alternative mechanism in the response to water shortage in Tullio.     

The accumulation of glycinebetaine during cold acclimation in early and late cultivars of barley

Summary Barley plants are able to accumulate glycinebetaine (betaine) at high levels in their leaves in response not only to water and salt stress but also to cold stress. Such accumulation of betaine during acclimation to cold is associated to some extent with freezing tolerance in leaves of barley plants, as previously demonstrated with near-isogenic lines that differed only in a single gene for the spring type of growth habit (Plant, Cell and Enyironment 17: 89–95, 1994). We now present evidence that the levels of betaine accumulated during cold acclimation might be associated with the earliness or lateness of the maturity of cultivars, namely, that late cultivars accumulate more betaine than early cultivars. Moreover, the grade of the vermalization requirement of the cultivars seemed unlikely to be associated with the level of betaine acumulated during cold acclimation. However, the trait that controlled accumulation of betaine during cold acclimation was not linked with the earliness or lateness of the maturity of cultivars. The higher levels of betaine in the late cultivars might have resulted from co-selection for lateness of maturity and freezing tolerance, which is generally a requirement in the areas of Japan where such late cultivars were originally cultivated.     

Effect of Foliar Applications of Glycinebetaine on Stress Tolerance, Growth, and Yield of Spring Cereals and Summer Turnip Rape in Finland

Crop losses caused by environmental stresses might be reduced by applying osmoprotectans to crop canopies. Glycinebetaine is endogenously accumulated by some halophytes under stress conditions and represents such a compound. Glycinebetaine was applied exogenously to barley ( Hordeum vulgare L.), oat ( Avena sativa L.), spring wheat ( Triticum aestwum L.), and summer turnip rape ( Brassica rapa ssp. oleifera DC.) canopies and its optimal concentration was monitored in the greenhouse. In field experiments the response of crop plants to betaine applications was assessed by measuring accumulation of above ground biomass, leaf area index (LAI), leaf chlorophyll, and yield. The optimum betaine concentration producing advantageous effects on growth and crop physiology in turnip rape was close to 0.1 M and for wheat 0.3 M. Such concentrations promoted accumulation of betaine similar to that of halophytes under stress conditions [ca. 200 μmol (g DM)⁻¹]. In the 1993 field experiment peak LAIs were recorded in irrigated wheat and barley treated with 17.5 kg ha⁻¹ betaine applied at 300 1 ha⁻¹. Green leaf area was slightly more persistent in wheat treated twice with 1 kg ha⁻¹ betaine applied at 200 1 ha⁻¹ in 1994, although it was not associated with increased grain yield. Our results indicated that betaine has no actual potential in Finland for the principal grain crops but further studies are needed in stress prone environments to assess the potential of betaine treatments for preventing crop failures.     

低温胁迫下外源甜菜碱对香蕉叶片和根系内源甜菜碱合成的影响

通过用不同浓度外源甜菜碱预处理香蕉幼苗后,置于人工气候箱中模拟低温胁迫,分别测定香蕉叶片和根系内源甜菜碱的含量和甜菜碱合成关键酶甜菜碱醛脱氢酶（BADH）活性,以研究外源甜菜碱对香蕉叶片和根系内源甜菜碱合成的影响。结果表明,一定浓度的外源甜菜碱可极显著提高香蕉幼苗叶片BADH活性,极显著促进叶片内源BT的积累,胁迫24 h后根系内源甜菜碱的含量虽显著高于常温对照,但BADH活性却无显著提升。结论：外源甜菜碱可促进低温胁迫下香蕉内源甜菜碱的合成和积累,叶片是其主要合成器官,根系可作为甜菜碱的贮存场所。