梨叶叶龄与梨黑星病菌侵染发病的关系

田间试验结果表明，鸭梨叶片在生长发育期抗病性差，易感染黑星病；发育成熟后，抗病性逐渐增强。自然条件下，受叶片抗病性和孢子着落量的综合影响，鸭梨成熟叶片很少感染黑星病。鸭梨叶片从展叶到发育成熟，在梨树生长发育前期（盛花期后60d内）约需40d，后期（盛花期60d后）约需30d。正处在生长发育期的鸭梨叶片受侵染，潜育期为18－25d，发病后，病斑大，产孢期短；成熟叶片受侵染，潜育期多在40d以上，发病后，病斑小，产孢期长。梨树生长前期梨黑星病的流行主要由于大部分叶片正处在生长发育期抗病性较差；后期果实发病则主要源于成熟叶片内长期潜育和长期产孢的黑星病菌。     

空气湿度对灰霉菌侵染番茄叶片组织结构分析及抗氧化系统的影响

 空气湿度对番茄灰霉病的发生有显著性影响。为了探明空气湿度对灰霉菌侵染番茄叶片的过程与机理,本研究以‘金棚14-6’番茄为材料,观察分析了高空气相对湿度(80%~95%)和低空气相对湿度(65%~80%)对灰霉菌侵染番茄叶片表型变化、细胞学差异、形态结构变化、活性氧含量和抗氧化酶的影响。结果表明:高湿接种60 h大量芽管伸长出现在叶片下表皮细胞并分化菌丝,叶肉细胞间隙分布了大量的菌丝并伴随病斑出现,灰霉菌在60 h完成侵染;低湿接种108 h芽管伸长出现在叶片下表皮并分化菌丝,叶肉细胞间隙有少量菌丝分布,没有明显病斑出现。随着灰霉菌的侵染,低湿与高湿相比栅栏组织和海绵组织结构从整齐紧密变为排列疏松的时间滞后;高湿和低湿处理的叶片厚度、栅栏组织和海绵组织厚度均呈先上升后下降的变化趋势,侵染后期低湿处理的叶片组织结构厚度显著高于高湿。随着接菌时间延长,高湿和低湿的活性氧含量和抗氧化酶活性处于相对活跃的调整、适应的变化过程,大致呈先上升后下降趋势,而对照和接菌相比无显著差异,变化趋势维持在基本的振幅上。研究显示灰霉菌发生的环境条件:湿度80%~95%和侵染完成时间60 h,即控制高空气湿度的持续时间在60 h内。这为设施内番茄灰霉病的湿度调控防治提供了理论基础。     

茶树叶片理化性质对茶蚜取食选择性的影响

为明确茶蚜Toxoptera aurantii Boyer de Fonscolombe寄主选择行为机理, 通过自由选择法研究有翅成蚜对7个茶树品种的取食选择性, 利用蚜量比值法对供试茶树品种进行抗性鉴定, 并进一步分析茶蚜取食选择性与茶树叶片物理性状及主要生化成分的相关性。结果表明, 有翅成蚜对7个茶树品种的取食选择性存在差异, 其中对‘黄金芽’的选择性最强, 而对‘黔茶1号’和‘黔茶10号’的选择性最弱。抗蚜性鉴定结果表明, 供试茶树品种中, ‘黔茶1号’‘黔茶10号’为抗虫品种; ‘福鼎大白茶’‘龙井43’‘黔茶8号’为中抗品种; ‘黔湄601’为感虫品种; ‘黄金芽’为高感品种。Pearson相关性分析显示, 茶蚜取食选择性与茶树叶片总厚度(r=-0.84)、下表皮厚度(r=-0.78)、栅栏组织厚度(r=-0.94)、咖啡碱含量(r=-0.91)、茶多酚含量(r=-0.94)呈显著负相关, 与气孔密度(r=0.93)、游离氨基酸含量(r=0.94)呈显著正相关, 而与海绵组织厚度(r=-0.27)、可溶性糖含量(r=0.75)无显著相关性。本研究可为我国抗蚜种质资源鉴选及利用、茶蚜的绿色防控提供理论依据。     

应用TaqMan real-time PCR研究BSV在带毒香蕉组培苗中传递

由香蕉线条病毒(Banana streak virus,BSV)引起的香蕉线条病,严重影响了香蕉产量及种质资源交流。本研究根据BSV ORF Ⅲ基因保守序列设计引物和探针,建立了BSV的实时荧光定量PCR检测方法。该法检测BSV时,与黄瓜花叶病毒(Cucumber mosaic virus,CMV)和香蕉束顶病毒(Banana bunchy top virus,BBTV)无交叉反应;不论是检测质粒DNA还是香蕉病株总DNA,其灵敏度都比普通PCR高,检测质粒DNA的灵敏度比普通PCR高100倍,检测香蕉病株总DNA的灵敏度比普通PCR高10倍,且具有良好的重复性。利用建立的实时荧光定量PCR方法检测我国主栽的不同香蕉品种‘大蕉’、‘粉蕉’和‘粤优抗一号’香蕉组培苗中BSV的浓度,发现不同品种BSV传递规律不同。‘大蕉’第3代、第9代组培分化芽中BSV含量较原代显著减少;‘粉蕉’中BSV含量随继代数增加表现为先增加后减少;‘粤优抗一号’中BSV含量随继代数增加呈增加趋势。BSV在‘粉蕉’、‘大蕉’和‘粤优抗一号’第10代到第12代组培苗中以顶部第1片或(及)第2片叶中含量最高。直接结合PCR分析初步表明不同品种在原代和组培至第12代,其植株中的BSV均为游离状态。本文通过对带毒香蕉组培苗中BSV的含量监测,明确了BSV在不同品种带毒香蕉组培苗中的传递和分布规律,为研究BSV与寄主互作及BSV检测提供了理论依据。     

油菜叶片性状及次生代谢物质与其对黄宽条跳甲抗性的关系及对跳甲解毒酶活性的影响

黄宽条跳甲是内蒙古西部地区春油菜苗期最重要的害虫。本研究测定了2个抗虫油菜品种‘太空蒙Ⅳ’和‘大黄油菜’及1个感虫品种‘青油14’的叶片性状、次生代谢物质及取食不同品种油菜后黄宽条跳甲解毒酶活性。结果表明,油菜叶片含水量高的抗虫性强。叶片茸毛短、密度低与‘太空蒙Ⅳ’抗虫性高度相关,蜡质含量高可能是‘大黄油菜’抗黄宽条跳甲的原因之一。油菜叶片总黄酮、总酚和总生物碱含量与抗虫性呈正相关;取食抗虫性高的油菜品种的黄宽条跳甲体内谷胱甘肽S-转移酶(GSTs)活性极显著高于感虫品种。     

梨黑星病菌分生孢子侵染及产孢研究

 梨黑星病(Venturia nashicola Tanaka et Yamamoto)是我国梨树的重要病害。为了深入了解该病在生长季节的发病流行规律,本研究采用水合三氯乙醛饱和水溶液或乳酚油透明液透明接种鸭梨叶片,研究了梨黑星病菌分生抱子侵入及产抱过程。     

TeMV与PWV侵染对西番莲代谢生理及组织微结构的影响

以西番莲品种‘台农1号’为实验材料,通过电镜扫描技术比较观测TeMV和PWV侵染与健康西番莲的叶片、幼嫩果实外果皮组织形态结构,分析测定其叶片生理生化变化,研究西番莲病毒侵染对西番莲叶片和幼嫩果实外果皮组织结构和生理生化的影响。结果表明：TeMV与PWV侵染后,西番莲植株叶片的海绵组织细胞间隙缩小,发生成团堆积状排列,栅栏组织细胞萎缩,呈不规则长条形;幼嫩果实外表皮组织中石细胞层发生严重断裂,排列松散,海绵层细胞变得松散,且发生较严重的木质化现象;叶片与幼嫩果实外表皮表面纹理粗糙、褶皱,气孔保卫细胞萎缩,气孔周围组织皱缩、粗燥;感病果实外果皮表面上的腺毛凸起无序。病毒侵染后,感病植株第1～3叶的蔗糖含量较第4～6叶的高23.11%;健康叶片则相对平衡,降低了淀粉积累、PG酶、纤维素酶与PPO酶活性,提高了感病植株第1～3叶的α-淀粉酶、GS酶与POD酶活性。西番莲受TeMV与PWV侵染后,植株叶片第1～6叶营养物质分配不平衡,相关物质的合成分解与抗氧化防御酶系统受伤害,叶片与果实组织形态结构受到不同程度的损坏,植株正常吸收功能遭到破坏。     

8个扁桃品种的生理解剖特性及其抗寒性比较研究

为鉴定引进甘肃地区的8个扁桃品种的抗寒性,以其一年生幼苗为试验材料,测定不同品种在6个低温梯度下的各项生理指标,运用Logistic方程计算出半致死温度(LT₅₀),并利用主成分分析对各品种的抗寒性综合评价,以期为扁桃抗寒品种选育及栽培提供理论依据。结果表明：不同品种的叶片和枝条组织解剖结构均具有差异性,且叶片栅栏组织厚度、栅海比、叶片紧密度(CTR)与抗寒性呈正相关。各品种的半致死温度(LT₅₀)为-21.43～-11.23℃,其中‘浓泊尔’‘索诺拉’和‘蒙特瑞’的枝条耐低温在-18℃左右,而‘晋扁1号’和‘普瑞斯’的枝条耐低温在-11℃左右。低温胁迫下,扁桃枝条的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性总体呈先升后降趋势,丙二醛(MDA)、可溶性糖和蛋白质含量随温度的变化表现为先升后降趋势,脯氨酸(Pro)含量总体呈逐渐上升趋势。综上,通过测定不同处理温度下的生理指标及显微结构观察表明,SOD活性、蛋白质含量、栅栏组织、海绵组织、皮层厚度是影响扁桃抗寒性强弱的重要指标。利用主成分分析进行综合评价,抗寒性强弱...     

‘赞皇大枣’和‘冬枣’对干旱胁迫的生理响应

以3 a生定干80 cm的‘赞皇大枣’和‘冬枣’为试材,设干旱和正常灌水两种处理,在处理21 d时测定其生长指标、叶绿素含量、光合及荧光参数、渗透调节物质含量、抗氧化酶活性和内源激素含量,分析两个枣树品种响应干旱胁迫的生理差异。结果表明：干旱胁迫主要抑制了两个枣树品种的新梢叶片数、叶片长度和枣吊长度,‘冬枣’的新梢节间数下降了45.5%,而‘赞皇大枣’的单株枣吊总数下降了45.61%。干旱胁迫后,‘赞皇大枣’和‘冬枣’的叶片叶绿素总含量分别下降了18.94%和29.32%。‘赞皇大枣’的光合、蒸腾速率在正常灌水和干旱胁迫后均高于‘冬枣’,而在正常灌水情况下,除F_m以外,二者的荧光参数值无显著差异。干旱胁迫后,‘赞皇大枣’的C_i无显著变化,而‘冬枣’的C_i降幅为48.07%。相比于‘冬枣’,干旱胁迫后‘赞皇大枣’的ΦPSⅡ和qP分别提高97.69%和77.25%,qN降低18.29%。正常情况下,两个枣树品种叶片的相对电导率、MDA和Pro含量无显著差异,‘赞皇大枣’的可溶性糖和可溶性蛋白含量比‘冬枣’分别高148.29%...     

葡萄白粉病抗性鉴定方法优化及品种抗性评价

本研究通过对叶盘保湿方法的改进, 不同菌源接种后发病严重度的分析, 抗?感病对照品种的确定, 建立了一种更为便捷?可靠?稳定的葡萄白粉病室内抗性鉴定方法:取葡萄藤自上而下第2~4片幼嫩叶片, 打取直径15 mm的叶盘置于1.5%水琼脂平板进行保湿, 采集田间菌源直接制备孢子浓度为2×105个/mL的孢子悬浮液接种, 选定抗?感病葡萄品种做对照, 14 d即可完成抗性鉴定?采用此方法对11个葡萄品种(品系)进行了葡萄白粉病抗性评价, 结果表明:供试的11个品种(品系)对葡萄白粉病的抗性存在明显差异, 其中高感品种为‘巨峰’‘夏黑’和‘阳光玫瑰’等, 感病品种为‘玫瑰香’和‘马瑟兰’, 抗病品种为‘瑞都科美’和‘无核翠宝’, 高抗品种为‘北冰红’?试验结果为葡萄抗病品种的选育及利用提供了方法和基础参考数据?     

梨抗黑星病AFLP标记筛选

 Pear scab caused by Venturia nashicola is one of the most destructive diseases of pears. Molecular markers linked to scab resistance gene is expected to be useful for improving pear. In this study, the F₁ population derived from the cross of ‘Huangguan’ and ‘Yali’ was analyzed genetically. The resistance of pear to scab was proved to be controlled by a single gene in a dominant manner. Bulked segregant analysis (BSA) was conducted to screen 64 fluorescent AFLP primer pairs. A marker designated as D3-365 was found to be linked to the resistant locus. Selective genotype linkage analysis showed that the genetic distance between the marker and the resistant locus was 14.9 cM.     

Ultrastructural study on acibenzolar-S-methyl-induced scab resistance in epidermal pectin layers of Japanese pear leaves

The infection behavior of Japanese pear scab pathogen Venturia nashicola race 1 was studied ultrastructurally in acibenzolar-S-methyl (ASM)-pretreated susceptible Japanese pear (cv. Kousui) leaves to determine the mechanism of ASM-induced scab resistance. On ASM-pretreated leaf surfaces, the infection behavior (conidial germination and appressorial formation) was similar to that on distilled water (DW)-pretreated leaves prior to cuticle penetration by the pathogen. However, after penetration, differentiated behavior was found in epidermal pectin layers and middle lamellae of the ASM-pretreated leaves. Subcuticular hyphae in epidermal pectin layers and middle lamellae of ASM-pretreated pear leaves were observed at lower frequency than in DW-treated leaves. The results indicated that fungal growth was suppressed in ASM-pretreated pear leaves. In the pectin layers of ASM- and DW-pretreated leaves, some hyphae showed morphological modifications, which were used as criteria to judge collapse of hyphal cells, including plasmolysis, necrotic cytoplasm, and cell wall destruction. More hyphae had collapsed in ASM-pretreated leaves than in DW-treated ones. In addition, the cell walls of collapsed hyphae broke into numerous fibrous and amorphous pieces, suggesting that ASM-induced scab resistance might be associated with cell-wall-degrading enzymes from pear plants. In addition, results from morphometrical analysis suggested that the activity or production of pectin-degrading enzyme from hyphae were inhibited by ASM application when compared with DW treatment.     

亚洲梨黑星病菌致病性及其寄主抗病机制的研究进展

梨黑星病是亚洲梨的主要病害之一。该病是由纳雪黑星病菌(Venturia nashicola)感染所致。V.nashicola主要寄生在亚洲梨叶片表皮细胞壁的果胶质层中。该菌的感染可能主要与分泌的细胞外分泌物质、角质分解酶、过氧化氢和果胶质分解酶有关。而亚洲梨对V.nashicola的抗性可能主要与多聚半乳糖醛酸酶抑制蛋白、多种病程相关蛋白、富亮氨酸重复类受体蛋白激酶等有关。另外,不具直接杀菌能力的系统抗性诱导剂acibenzolar-S-methyl(ASM)在大田试验中对梨黑星病菌有较好控制效果。这与ASM诱导的植物防御反应,包括多聚半乳糖醛酸酶抑制蛋白和几丁质酶等有关。     

Effects of temperature and continuous and interrupted wetness on the infection of pear leaves by conidia of Venturia nashicola

Experiments were conducted to determine: (i) the effects of temperature and duration of continuous wet periods on the infection of pear seedlings by conidia of Venturia nashicola , the causal agent of pear scab; and (ii) the effects of the length and temperature of dry interrupting periods on the mortality of infecting conidia. Average number of scab lesions per leaf increased with increasing duration of wetness. Logistic models adequately described the change in the average number of scab lesions per leaf at 5, 10, 15, 20 and 25°C over the wetness duration. At 30°C, only a few lesions developed. Simple polynomial models satisfactorily described the relationship of the three logistic model parameters (maximum number of lesions, rate of appearance and the time to 50% of the maximum number of lesions) with temperature. The optimum temperature for infection was found to be approximately 20°C. The relationship between mortality and the length of a dry period interrupting an infection process can be satisfactorily described by an exponential model. The rate of mortality at 10, 16 and 22°C did not differ significantly, but was significantly less than that at 28°C.     

Induced Resistance of Acibenzolar-S-methyl (CGA 245704) to Cucumber and Japanese Pear Diseases

Antifungal activity of the novel compound acibenzolar-S-methyl (CGA245704: benzo[1,2,3]thiadiazole-7-carbothioic acid S-methyl ester) was examined in vitro. No remarkable activity was observed on mycelial growth and conidial germination of almost all fungi tested. Only melon isolates of Didymella bryoniae were sensitive to this compound. On potted plants, acibenzolar-S-methyl showed control efficacy on anthracnose and scab of cucumber and rust of Japanese pear but not on Fusarium wilt of cucumber. In field trials, the occurrence of both rust and scab on Japanese pear was suppressed with this compound. Based on these experiments, it was suggested that acibenzolar-S-methyl induced resistance to some but not all diseases on cucumber and Japanese pear. Induction of disease resistance in cucumber was rapidly triggered after treatment with acibenzolar-S-methyl.     

冬型中国梨木虱在梨树不同部位的产卵特点

昆虫母代产卵部位的选择特点直接影响到子代的生存适应性,但已有研究对冬型中国梨木虱产卵部位选择特点尚未明确。本研究调查了冬型中国梨木虱随时间变化在梨树花芽、叶芽、枝条基部、花柄、幼叶上产卵特点的变化。结果表明,冬型梨木虱产卵期约45 d,以枝条基部刻痕处着卵量最大,显著高于其他部位。冬型梨木虱产卵部位的选择随梨树的物候变化而变化:萌芽前,优先选择枝条顶芽,其次在腋芽和枝条基部刻痕处产卵;花期和展叶期,花芽、叶芽、枝条基部刻痕处着卵量下降,主要于花柄和幼叶部位产卵;冬型梨木虱产卵部位的选择顺序依次为花芽、叶芽、枝条基部、花柄、幼叶。本研究明确了冬型梨木虱在梨树不同部位产卵的变化特点,研究结果可用于指导梨木虱防控。     

甘薯品种对疮痂病的抗性及其机理分析

为查明我国南方甘薯主栽品种抗疮痂病的能力,用疮痂菌孢子悬液对16份品种作苗期接种与田间病情系统观察.结果表明,广薯79-15、潮薯1号等8份表现感病-中感;福薯26、广薯88-70等8份表现中抗-高抗;不同抗、感品种在田间表现长短不一的感病期.对6份品种藤蔓不同的部位和株龄的组织结构作显微测量与计数、接种试验以及糖含量测定显示,不同品种皮层组织结构差异决定对疮痂病的抗、感性;抗病品种藤蔓具有较厚的角质层,叶片气孔和幼嫩组织的腺鳞数目都较少,表现潜育期长,病斑少.且同一品种不同株龄皮层结构差异与感病程度间有密切关系,但其藤蔓糖含量与品种抗性之间不相关.     

Factors affecting the severity of bacterial canker of pear caused by Pseudomonas syringae pv. syringae

Several factors affecting the severity of bacterial canker of pear were studied. In the orchard, infection of shoots by Pseudomonas syringae pv. syringae occurred only when the inoculum dose exceeded 10⁶ colony-forming units/shoot. However, under favourable conditions in a growth chamber, cankers formed on detached shoots inoculated with 5 cfu/shoot. A second-order polynomial relationship was established between log₁₀ transformed canker length and log₁₀ transformed inoculum dose. In orchard and growth chamber experiments, shoots were susceptible from the time of bud swell until after fruit harvest. The severity of Pseudomonas canker of detached shoots increased if they were frozen at – 10°C for 24 h before inoculation. Shoots were most susceptible when inoculated immediately after wounding, and no cankers developed in the orchard when 3-day-old wounds were inoculated. Additionally, no cankers resulted from inoculation of leaf scars at leaf drop. Actively growing, current-season shoots were more susceptible than shoots that had set a terminal bud. The practical implications of these results are discussed as a basis for control of bacterial canker of pear.     

Mapping Quantitative Field Resistance Against Apple Scab in a 'Fiesta' x 'Discovery' Progeny

ABSTRACT Breeding of resistant apple cultivars (Malus x domestica) as a disease management strategy relies on the knowledge and understanding of the underlying genetics. The availability of molecular markers and genetic linkage maps enables the detection and the analysis of major resistance genes as well as of quantitative trait loci (QTL) contributing to the resistance of a genotype. Such a genetic linkage map was constructed, based on a segregating population of the cross between apple cvs. Fiesta (syn. Red Pippin) and Discovery. The progeny was observed for 3 years at three different sites in Switzerland and field resistance against apple scab (Venturia inaequalis) was assessed. Only a weak correlation was detected between leaf scab and fruit scab. A QTL analysis was performed, based on the genetic linkage map consisting of 804 molecular markers and covering all 17 chromosomes of apple. With the maximum likelihood-based interval mapping method, eight genomic regions were identified, six conferring resistance against leaf scab and two conferring fruit scab resistance. Although cv. Discovery showed a much stronger resistance against scab in the field, most QTL identified were attributed to the more susceptible parent 'Fiesta'. This indicated a high degree of homozygosity at the scab resistance loci in 'Discovery', preventing their detection in the progeny due to the lack of segregation.