虫压胁迫对抗虫转基因水稻生长发育及产量性状的影响

在大田条件下,以转基因抗虫水稻Bt63、R1和R2及非转基因水稻汕优63(对照)为材料,设置高、低两种虫压环境条件,研究虫压胁迫对转Bt抗虫基因水稻生长发育及产量相关性状的影响.结果表明： 抗虫水稻在虫压胁迫条件下可充分体现出外源基因的抗性特点.在高虫压条件下,3种转Bt基因水稻受螟虫危害程度远低于对照植株,株高、分蘖数、地上部鲜质量、穗长、穗质量、单株穗数、单株实粒数、实粒质量、结实率、千粒重等生长发育和产量指标均高于对照,但仅株高、分蘖数和穗长3个指标与对照有显著差异.因此,抗虫外源Bt基因的引入对水稻结实性不会产生负面效应,高虫压胁迫条件对抗虫转基因水稻产量的影响较小.     

不同栽培条件辣椒疫霉菌ITS序列同源性分析

由疫霉菌引起的辣椒疫病是辣椒生产上的主要病害。明确设施栽培辣椒土传病害和露地栽培条件下辣椒疫病疫霉病菌基因序列和同源性,为制定病害防治措施提供依据。通过病菌形态观察、ITS基因序列测定与同源性分析开展研究。由疫霉菌侵染的辣椒病害在设施和露地不同栽培形式下发生部位略有不同,但在病菌形态上表现一致,ITS基因序列同源性极高,达到了99%以上。设施土传病害和露地栽培条件下辣椒疫病菌属于同一种,均为辣椒疫霉菌(Phytophthora capsici Leonian)。     

对增强辣椒疫霉菌抗性的研究

病原物诱导型启动子能精确控制抗病基因在侵染位点的表达,是抗病基因工程的有效工具。prp1-1是来自马铃薯谷胱甘肽巯基转移酶基因启动子的一个273bp的片段,能够快速准确地启动被侵染位点抗病基因的表达;Rs-AFP2是具有对致病性丝状真菌的广谱抗性。该研究构建prp1-1调控Rs-AFP2基因表达的载体,经农杆菌介导转化法导入辣椒。逆转录PCR检测发现,转基因辣椒只在受到疫霉菌孢子侵染时,才由prp1-1启动Rs-AFP2基因的转录。用疫霉菌孢子灌根接种转基因辣椒T1代植株,35株T1代辣椒中有29株表现出明显的疫霉菌抗性。另将23株T1代辣椒种于人工气候箱,发现其形态和发育特征与相同条件下的非转基因植株无明显区别。研究表明,prp1-1调控Rs-AFP2的诱导表达达到了增强辣椒疫霉菌抗性的目的,而且避免了负面效应的发生。     

转基因抗虫棉的产量、品质及抗虫性比较研究

对36个转基因抗虫棉品种(品系)进行试验,比较了它们的产量、抗棉铃虫和红铃虫特性以及纤维品质之间的差异,并进行综合评价。在不打药的情况下,筛选出252等13份皮棉产量比鄂抗9号显著提高、抗棉铃虫和红铃虫的种质材料,其纤维品质综合性状表现一般。     

耐非生物胁迫转基因水稻的培育——现在和未来

环境胁迫严重降低了作物产量,日益减少的耕地和膨胀的人口对世界粮食安全造成了威胁。长期以来,改善作物的抗逆性一直是农业生产的主要目标。水稻是重要的粮食作物之一,培育具有抗逆性的水稻品种对全球的粮食生产将产生重要影响。在改善水稻的抗逆性方面,转基因比传统方法更有发展潜力。近年来,已有许多抗逆相关基因转入水稻并获得了一些提高抗逆性的转基因植株,文章重点讨论了耐非生物胁迫转基因水稻的研究进展。     

应用B.t.和SBTi基因提高水稻抗虫性的研究

用基因枪法将单个B.t.基因或与SBTi基因一起导入到两个华南地区优良籼稻品种中,获得21个转B.t.单基因的植株系,4个转B.t.和SBTi双基因的植株系。对R1代植株的分子杂交和遗传分析表明,3个转双基因系中多个拷贝的B.t.和SBTi基因均是整合在植株基因组同一染色体上相同或相近位点。Northern blot证明在R2代转基因植株中B.t.基因稳定表达。对稻纵卷叶螟的抗性实验表明,转B.t.单基因或B.t.和SBTi双基因的转基因植株均较原种对照有更强的抗性,而转双基因植株较转单基因植株又有更强的抗性。     

淹涝胁迫对水稻生育后期的生理特性和产量性状的影响

比较研究了水稻（湘中灿３号）在生育后期（孕穗期和乳熟期）进行没顶淹水胁拓处理后几个相关的生理指标和生长发育、产量的形态指标。研究结果显示水稻受淹后完全伸展叶片净光合速率降低,叶绿素含量在孕穗期明显降低,但在乳熟期只有少量下降。电导率明显增加,细胞膜透性增大,脯氨酸含量增加。奶系伤流量和,根系活力降低经与中群伤流液中的主要基酸如Ａｌａ,ＯＰｒｏ,Ｐｈｅ的含量增加,根系伤流量减少,根系活力降低,伤流液     

气候变化与水稻生长发育及产量形成关系的模拟研究

应用水稻生长日历模拟模型(RICAM1.3)模拟亚洲地区不同地点和不同气候条件下水稻的生育期和产量形成.其中3s-Beta模型被用于预测水稻开花期和描述水稻光温反应的3个连续阶段:基本营养生长期、光敏感期和光敏感后期.从时间与地理梯度的变化对水稻产量进行模拟,以中国、日本和菲律宾作为从北到南的地理梯度,以20世纪80年代气候变化作为时间梯度,应用RICAM1.3进行模拟.结果表明,模型具有广泛的适应性,能较好地模拟不同气候条件和不同水稻品种生育期的变化与产量的形成.     

转铜/锌超氧化物歧化酶和抗坏血酸过氧化物酶基因马铃薯的耐氧化和耐盐性研究

高盐等逆境可以加剧植物体内活性氧的产生,进而引起植物细胞死亡。为开发抗逆境作物,以置于氧化诱导型启动子下定位于叶绿体的转铜/锌超氧化物歧化酶（Cu/ZnSOD）和抗坏血酸过氧化物酶基因(APX)马铃薯为材料,研究了其对MV和 NaCl所引起的氧化胁迫的耐受性。结果表明, MV胁迫下,转基因马铃薯叶片膜的相对电导率明显低于对照; NaCl胁迫下,其叶绿素含量高于对照。 在含NaCl 的培养基上,转基因幼苗生根率明显大于对照。另外,NaCl胁迫下转基因马铃薯叶片的SOD和APX酶活性显著高于对照,与其耐盐性的提高相一致。这些研究表明,转入Cu/ZnSOD和APX基因的马铃薯清除活性氧的能力增强,抗逆性得到提高。本实验采用氧化诱导型启动子调控下的SOD和APX两个基因协同作用,使外源基因只有在逆境胁迫时才特异性表达,增强转基因植株的抗逆效果,为培育抗逆经济作物开阔了思路。     

优质抗疫病甜椒种质资源的选育

本文利用国外引进的2个抗疫病的商业品种,通过系谱法选择,获得了6个园艺性状普遍优于茄门、对疫病达到抗病和高抗水平的株系,其中有4个株系兼中抗CMV和TMV,另有1个株系兼抗CMV.其中20079-0-3-1-27和20080-0-1-3-29综合表现尤其突出.开展优质抗疫病甜椒种质资源的选育,将为国内抗疫病的甜椒育种起到积极的作用.     

An investigation of biological attributes that may contribute to the importance of Phytophthora capsici as a vegetable pathogen in Florida

During the 1999–2000 and 2000–2001 seasons, 19 commercial squash fields in the vicinity of Homestead, Florida (USA) were examined for diseases caused by Phytophthora capsici. In each of the six fields in which two or more isolates of P. capsici were recovered, both the Al and A2 mating types were present, and both mating types were recovered from the same plant five times. Insensitivity to mefenoxam was common among isolates, with EC50s ranging from 5 μg mefenoxam ml^?1 to more than 60 μg ml^?1. Of 15 weed species that were examined as possible alternative hosts of the pathogen, only common purslane, Portulaca oleracea, was infected by P. capsici. Few or no oospores of the pathogen formed in a glasshouse (c. 28°C) when artificially inoculated pepper plants were covered with plastic bags or kept under continuous mist. In studies in the laboratory (c. 22°C) with detached pepper leaves, no oospores were formed on wire screens over water reservoirs. Consistent production of oospores occurred only when leaves were in constant contact with water. Maximum production occurred at 18°C, and production also occurred at 14°C, 20°C, 24°C and 26°C, but not at 6°C, 12°C, 30°C and 32°C.     

Inhibitory Effect of Paenibacillus polymyxa GBR-462 on Phytophthora capsici Causing Phytophthora Blight in Chili Pepper

In the present work 25 strains of Paenibacillus polymyxa isolated from rotted ginseng roots were screened for their antimicrobial activity against Phytophthora capsici in vitro . Based on antimicrobial activity, 15 strains categorized as strongly antimicrobial, among them GBR-462 was found as the most active, and five strains each as weekly antimicrobial and no antimicrobial. Antimicrobial activity was influenced by the initial inoculum density, as strains of P. polymyxa with a strong antimicrobial activity (including P. polymyxa GBR-462) showed the antimicrobial activity against P. capsici and could form biofilm only when they were applied at the higher initial inoculums, 10⁸ cfu/ml. No inhibitory effect was noted on the mycelial growth and zoospore germination of the pathogen when applied at the lower inoculum density of 10⁶ cfu/ml of P. polymyxa GBR-462. However, sporangium formation and zoospore release was significantly inhibited at the lower inoculum density. Also light and electron microscopy revealed the structures of sporangia aberrant with no or few healthy nuclei, indicating sporangium and zoospore formation inhibited at the lower inoculum density. Application of P. polymyxa GBR-462 into potted soil suppressed disease progression as well as disease severity; disease severity was reduced by 30% as compared to untreated pots, suggesting P. polymyxa GBR-462 could be a potential biocontrol agent against Phytopthora capsici .     

Effect of oxathiapiprolin on asexual life stages of Phytophthora capsici and disease development on vegetables

Phytophthora blight caused by Phytophthora capsici is a serious disease in the production of peppers and other vegetables worldwide. Application of fungicides is an important component in developing effective disease management programmes. However, resistance in P. capsici populations to some commonly used fungicides has been documented. Identification of effective new fungicides with different mode of actions is highly desirable. This study was conducted to determine baseline sensitivity of P. capsici isolates to oxathiapiprolin, the first member of a new class of isoxazoline fungicides, and efficacy of this compound for reduction of Phytophthora blight on bell pepper. A collection of 126 P. capsici isolates were evaluated and all the isolates were sensitive to oxathiapiprolin. EC₅₀ values of oxathiapiprolin in inhibiting mycelial growth, sporangium formation and zoospore germination of 25 selected isolates averaged 0.001, 0.0003 and 0.54 µg mL^?1, respectively. It appeared that asexual life stages of P. capsici were more sensitive to oxathiapiprolin than other compounds used for control of oomycete pathogens. In field studies, oxathiapiprolin applied at different rates through drip irrigation tubes, or by soil drench plus foliar sprays, reduced Phytophthora blight and increased pepper yield significantly. This is the first report of the efficacy of oxathiapiprolin in suppression of P. capsici, which indicates that oxathiapiprolin is effective in inhibiting the pathogen and has the promise to be a viable option for managing Phytophthora blight in bell pepper production.     

土壤中辣椒疫霉分离方法的研究与量化测定

从杭州、西安、广州及武汉等辣椒病田分别采集土样 ,室内晾干研碎后 ,用选择性培养基 ,采用土壤稀释平板法和组织诱饵法分离辣椒疫霉 (PhytophthoracapsiciLeonian) ,并对土壤中辣椒疫霉的密度进行量化处理。结果表明 ,利用选择性燕麦培养基 ,采用土壤稀释平板法可分离获得大量的辣椒疫霉菌株 ,而且辣椒连作田的辣椒疫霉菌密度高于轮作田。组织诱饵法试验结果表明 ,辣椒叶片诱集效果最好 ,其次是辣椒果实。     

疫霉侵染下辣椒幼苗消减文库的构建与初步分析

为了分离和鉴定辣椒中疫霉诱导基因,以高抗疫霉病辣椒品种L11为材料,以接种辣椒疫霉菌的幼嫩叶片为处理（tester）,以未接种自然生长的幼嫩叶片为对照(driver),利用抑制性消减杂交技术(suppression subtractive hybridization,SSH)构建了疫霉侵染下辣椒幼苗的消减文库。从消减文库中随机挑取30个阳性克隆,提取质粒进行PCR鉴定,显示插入片段大小大部分集中在200～1 000 bp之间,文库质量良好。随机挑取40个克隆进行测序,共获得35个有效EST序列。经Blastx分析表明：有30个EST与GenBank中其他序列有同源性,5个EST为未知功能序列。已知功能的EST序列分别编码NAC转录因子、丝氨酸/苏氨酸蛋白激酶、P450单加氧酶、叶绿素a/b结合蛋白、谷胱甘肽转移酶、几丁质酶等,这些蛋白涉及抗病信号传递、抗氧化作用、转录调控及光合作用等多种生理过程。本研究为抗病基因克隆和系统研究疫霉侵染下辣椒基因的表达奠定了重要的理论基础。     

Capsidiol: Its role in the resistance of Capsicum annuum to Phytophthora capsici

Inoculation of the stems of three Capsicum annuum L. cultivars showing different degrees of sensitivity to the fungal pathogen Phytophthora capsici , resulted in a hypersensitive reaction being expressed along the stems. One of the peppers (cv. Smith-5) showed resistance by total inhibition of fungal growth. Capsidiol, a phytoalexin, which accumulates in the area of necrosis appears to be involved in this resistance. Capsidiol accumulation was analyzed by gas chromatography and was correlated with the restricted growth of P. capsici , in vivo and in vitro, confirming the former's fungistatic and fungitoxic properties. The capacity to inhibit pathogenic growth was evident only when capsidiol production exceeded 1 204 μg ml^-1, a level reached in the resistant variety after 6 days of incubation. Experiments on induced resistance showed that a second inoculation of the stems of the three cultivars also resulted in necrosis and in an accumulation of capsidiol, although to a lesser extent than in the first inoculation. The greater accumulation of capsidiol in the stems of cv. Smith-5 is in accordance with the resistance shown by this cultivar to P. capsici , and confirms the implication of capsidiol in the disease resistance of this cultivar to fungal pathogens. Capsidiol has a fungistatic character at a mean concentration of 3.75 mM, and is fungitoxic at levels above 5 mM. This level must be exceeded and all the growing hyphae must be affected for capsidiol to qualify from being fungistatic to being fungitoxic.     

Defence response of pepper (Capsicum annuum) suspension cells to Phytophthora capsici

Cell suspension cultures of three cultivars of Capsicum annuum L., with different degrees of sensibility to the fungus Phytophthora capsici, responded to elicitation by both lyophilized mycelium and fungus filtrate. They showed conductivity changes, browning, production of the phytoalexin capsidiol and synthesis or accumulation of pathogenesis-related (PR) proteins with glucanase (EC 3.2.1.39) and chitinase (EC 3.2.1.14) activities. The cultivation medium was optimised for growth of both the plant and the fungus in order to avoid any stress during their combination. The resistant cv. Smith-5, showed a more rapid and intense response to the elicitor preparations than the sensitive cvs Americano and Yolo Wonder. This was particularly evident when the cell suspensions were elicited with the filtrate, when differences became clearly visible after only 6 h incubation. The greatest rate of capsidiol accumulation occurred after 18 h in the mycelium-elicited cells and after 12 h in those elicited with the filtrate. These times are the optimal for capsidiol accumulation, and the phytoalexin is produced much more rapidly than it can be excreted into the extracellular medium. The inhibition threshold of fungal growth (300 µg capsidiol [g dry weight]^?1) was reached only in the resistant cultivar. The induction of an intracellular glucanase (pI 8.9 and R_f 0.18) and an extracellular chitinase (pI 5.4 and R_f 0.70) only in the resistant cultivar 24 h after elicitation suggests that these enzymes are involved in the resistance to Phytophthora capsici, while other hydrolases common to all three cultivars form part of a more general defence. The results indicate that elicitation of pepper cell suspension cultures by signal molecules from P. capsici exhibits properties of a multicomponent dynamic system in which different protective mechanisms play complementary roles in the overall expression of the defence reaction. We confirm that the differential responses of resistant and susceptible pepper cultivars to P. capsici previously seen in plant stem sections are retained in suspension culture.     

Biological Control of Oomycete Soilborne Diseases Caused by Phytophthora capsici,Phytophthora infestans,and Phytophthora nicotianae in Solanaceous Crops

Oomycete pathogens that belong to the genus Phytophthora cause devastating diseases in solanaceous crops such as pepper, potato, and tobacco, resulting in crop production losses worldwide. Although the application of fungicides efficiently controls these diseases, it has been shown to trigger negative side effects such as environmental pollution, phytotoxicity, and fungicide resistance in plant pathogens. Therefore, biological control of Phytophthora-induced diseases was proposed as an environmentally sound alternative to conventional chemical control. In this review, progress on biological control of the soilborne oomycete plant pathogens, Phytophthora capsici, Phytophthora infestans, and Phytophthora nicotianae, infecting pepper, potato, and tobacco is described. Bacterial (e.g., Acinetobacter, Bacillus, Chryseobacterium, Paenibacillus, Pseudomonas, and Streptomyces) and fungal (e.g., Trichoderma and arbuscular mycorrhizal fungi) agents, and yeasts (e.g., Aureobasidium, Curvibasidium, and Metschnikowia) have been reported as successful biocontrol agents of Phytophthora pathogens. These microorganisms antagonize Phytophthora spp. via antimicrobial compounds with inhibitory activities against mycelial growth, sporulation, and zoospore germination. They also trigger plant immunity-inducing systemic resistance via several pathways, resulting in enhanced defense responses in their hosts. Along with plant protection, some of the microorganisms promote plant growth, thereby enhancing their beneficial relations with host plants. Although the beneficial effects of the biocontrol microorganisms are acceptable, single applications of antagonistic microorganisms tend to lack consistent efficacy compared with chemical analogues. Therefore, strategies to improve the biocontrol performance of these prominent antagonists are also discussed in this review.     

Anti-Oomycete Activity and Pepper Root Colonization of Pseudomonas plecoglossicida YJR13 and Pseudomonas putida YJR92 against Phytophthora capsici

Previously, Pseudomonas plecoglossicida YJR13 and Pseudomonas putida YJR92 from a sequential screening procedure were proven to effectively control Phytophthora blight caused by Phytophthora capsici. In this study, we further investigated the anti-oomycete activities of these strains against mycelial growth, zoospore germination, and germ tube elongation of P. capsici. We also investigated root colonization ability of the bacterial strains in square dishes, including cell motility (swimming and swarming motilities) and biofilm formation. Both strains significantly inhibited mycelial growth in liquid and solid V8 juice media and M9 minimal media, zoospore germination, and germ tube elongation compared with Bacillus vallismortis EXTN-1 (positive biocontrol strain), Sphingomonas aquatilis KU408 (negative biocontrol strain), and MgSO₄ solution (untreated control). In diluted (nutrient-deficient) V₈ juice broth, the tested strain populations were maintained at >10⁸ cells/ml, simultaneously providing mycelial inhibitory activity. Additionally, these strains colonized pepper roots at a 10⁶ cells/ml concentration for 7 days. The root colonization of the strains was supported by strong swimming and swarming activities, biofilm formation, and chemotactic activity towards exudate components (amino acids, organic acids, and sugars) of pepper roots. Collectively, these results suggest that strains YJR13 and YJR92 can effectively suppress Phytophthora blight of pepper through direct anti-oomycete activities against mycelial growth, zoospore germination and germ tube elongation. Bacterial colonization of pepper roots may be mediated by cell motility and biofilm formation together with chemotaxis to root exudates.