黄瓜霜霉病病原与抗病性研究进展

文章主要对黄瓜霜霉病菌有性阶段和初侵染源、霜霉病菌的保存方法和生理小种分化以及黄瓜霜霉病抗性遗传的研究现状进行了综述,提出了目前存在的问题并对今后进行了展望。     

新型杀菌剂吲唑磺菌胺对黄瓜霜霉病的防治效果研究

2012和2013两年田间药效试验结果表明,吲唑磺菌胺200g/L悬浮剂对黄瓜霜霉病具有较好防效,使用80g(ai)/hm2的末次防效达82%以上,是防治黄瓜霜霉病较为理想的药剂,在推荐用量下使用对黄瓜安全。     

黄瓜霜霉病诱导抗性的研究进展

霜霉病是世界上危害瓜类作物的主要叶部病害之一,每年造成较大经济损失。本文归纳了不同因子对黄瓜霜霉病诱导抗性方面的研究成果及最新进展,国内外的研究中,以化学诱导因子研究的较多,也较深入,生物及物理因子研究的较少。文章同时还对黄瓜霜霉病诱导抗性研究动态进行展望。     

BTH和K2HPO4诱导黄瓜抗霜霉病研究

研究了苯基(1,2,3)噻二唑-7-硫代羧酸硫甲酯(BTH)和磷酸氢二钾(K2HPO4)诱导黄瓜对霜霉病(Pseudoperonospora cubensis)的抗病性。结果表明,0.1~0.7 mmol/L BTH均能诱导黄瓜抗霜霉病,其中0.3~0.7 mmol/L BTH处理效果较好,分别达66.41%、68.60%和65.84%,处理后3 d诱导抗病性明显,并可持续9 d以上;K2HPO4以50 mmol/L诱导效果较好,达57.38%,处理后3 d抗病性明显。诱导产生的黄瓜对霜霉病的抗性为系统抗病性。     

棱角丝瓜不同品种对霜霉病抗性的相关研究

用不同抗性的丝瓜品种为材料,通过对气孔、糖含量、过氧化物酶、多酚氧经酶等多项指标的测定,结果表明：线瓜叶片中多酚氧化酶活性、还原性糖／可溶性糖比值、叶处表皮气孔密度与丝瓜对霜霉病的抗性呈负相关,其相关系数分别为－０．９８６１、－０．７１６５、－０．９６９２;而可溶性总糖含量与抗病性呈正相关（ｒ＝０．９１１５）;与还原性糖含量及过氧化物酶活性无关,气孔大小与抗病性无关。     

黄瓜霜霉菌ITS区序列分析反应体系的构建及优化

文章以黄瓜霜霉菌为材料,采用改良的CTAB方法提取基因组DNA,研究了黄瓜霜霉菌ITS区序列分析中PCR反应体系的各主要成分对检测结果的影响,确立了适宜的退火温度和反应体系。优化后的反应体系(25μL)为:采用引物ITS1/ITS4各40 ng,60 ng DNA模板,2.5 mmol·L-1 Mg2+2.0μL,2.5 mmol·L-1 dNTP 1.5μL,Taq酶1 U。优化的PCR扩增程序为:94℃预变性3 min,94℃50 s,52.2℃40 s,72℃1.5 min。在这一条件下运行35个循环;72℃延伸7 min。采用此反应体系和扩增程序,对采自黑龙江省不同地区的31份黄瓜霜霉菌基因组DNA进行PCR扩增,均可得到一条约为900 bp的条带。     

地果地上部分抑菌活性研究

采用孢子萌发法和菌丝生长法测定地果地上组织甲醇提取物对黄瓜霜霉病菌和马铃薯晚疫病菌的抑菌活性,提取物对2种供试病菌的孢子囊萌发,对马铃薯晚疫病菌菌丝生长均具有强烈的抑制作用,浓度为1 000 μg/mL时,抑制率均达到90%。盆栽试验和田间药效试验结果表明,10%的地果提取液稀释100倍对黄瓜霜霉病菌和马铃薯晚疫病菌的盆栽防效分别为85.89%和93.82%,对黄瓜霜霉病的防效为76.76%。     

室内黄瓜霜霉病防治方法的研究

黄瓜霜霉病菌属专性寄生菌,无法在培养基上生长,只能在活体上进行抑菌测试试验。从黄瓜栽培、病菌接种、病级划分标准和防效计算几个方面介绍了室内防治黄瓜霜霉病的研究方法。     

Cadmium accumulation and distribution in cucumber plant

An experiment developed in soilless culture was used to study the cadmium (Cd) accumulation, and distribution of Cd in cucumber (Cucumis sativus var. peonero‐mixfl) plant. Four treatments were established (0, 5, 10, and 20 mg Cd⁺² L^‐1). Uptake, and transport of Cd were increased with time, and Cd concentration in the nutrient solution. Fruit accumulation of Cd varied from 16 to 92 mg kg^‐1 depending on the treatments. The fresh weight, and dry matter accumulation of cucumber plant organs (roots, stem, leaves, and fruits) was affected by cadmium treatment. A decrease of the total, a, and b chlorophyll increasing Cd concentration in nutrient solution, and time of experiment were observed. The incidence of this metal on the content of chlorophyll b seem to be faster than chlorophyll a. Cucumber plant could be a feasible plant for pollution experiments due to their high sensibility, and transport efficiency.     

Hypovirulence detected in Brazilian isolates of Cryphonectria cubensis

A single 3 kb segment of double-stranded (dsRNA) was present in three of 30 Brazilian isolates of Cryphonectria cubensis . These dsRNA-containing isolates showed morphological characteristics suggestive of hypovirulence and were significantly less virulent than dsRNA-free isolates. One isolate, however, with morphological characteristics suggestive of hypovirulence, showed reduced virulence, but was free from dsRNA. Conversion of virulent isolates with normal morphology to a morphology associated with hypovirulence was achieved by pairing hypovirulent and virulent isolates of the same vegetative compatibility group (VCG). This suggests that dsRNA can be transmitted to isolates of the same vegetative compatibility group by hyphal anastomosis. Converted isolates exhibited the same hypovirulence-associated traits as those of the original dsRNA-containing hypovirulent isolates. These studies suggest that a single 3 kb segment of dsRNA alters both morphology and virulence by conferring hypovirulence on the pathogen; the first such report for Brazilian isolates of C. cubensis .