Heterodera glycines Cyst Components and Surface Disinfestants Affect H. glycines Hatching

We investigated the effects of Heterodera glycines cyst components and surface disinfestants on hatching of H. glycines eggs in vitro. Eggs were incubated in either H. glycines cyst wall fragments, cyst wall and egg rinsate, egg homogenate, or control solutions of soybean root diffusate, sterile distilled water, or zinc sulfate. Hatch in cyst wall and egg rinsate, and egg homogenate, was greater (α = 0.05) than hatch in sterile distilled water; however, it was not different from hatch in zinc sulfate according to Dunnett''s test. Hatch in cyst wall fragments was similar to hatch in sterile distilled water. To determine whether surface disinfestants affected hatch, eggs were treated first with chlorhexidine diacetate, mercuric chloride, sodium hypochlorite, or streptomycin sulfate and then incubated in H. glycines egg homogenate, soybean root diffusate, sterile distilled water, or zinc sulfate. Hatch of eggs treated with chlorhexidine diacetate, mercuric chloride, and streptomycin sulfate was reduced (α = 0.05), and hatch of eggs treated with sodium hypochlorite was increased (α = 0.05) relative to hatch of nontreated eggs in all incubation solutions except zinc sulfate according to Dunnett''s Test. Hatch in zinc sulfate was similar among all surface disinfestants except mercuric chloride, where hatch was reduced relative to hatch of nontreated and other surface disinfestant-treated eggs.     

Establishment of contaminant-free perennial plants in vitro

Summary Perennial plant tissue cultures are established by disinfecting field or greenhouse-grown plant parts and transferring them to sterile medium in vitro. Typically, shoots harvested from field or greenhouse-grown plants are placed in water, either to force growth from dormant branches or to maintain them until ready for explanting. In spite of extreme care, 90 to 100% contamination rates in newly established in vitro cultures are not unusual. Experience has identified several routine procedures that reduce contamination, such as minimizing the amount of time a stem cutting is maintained in water before being explanted, adjusting pH of the medium to a more acidic condition, and using pH neutralized bleach to sterilize instruments during subculture. Other methods to reduce contamination include establishing field-grown plants in a greenhouse where inoculum levels can be better controlled, trellising vining plants to get them off the soil, avoiding wetting foliage, and selecting vigorous explants that are not in contact with soil.     

低温茬口空闲期土壤强还原消毒对西瓜枯萎病的影响

为探明低温茬口空闲期土壤强还原消毒(RSD)对西瓜枯萎病的防控效果,设置对照(CK)、淹水对照(FCK)、淹水添加2%(w/w)苜蓿粉(AL)、0.25%(w/w)乙酸(AC)以及AL+AC的RSD处理进行西瓜盆栽试验,采用定量PCR和Illumina Miseq等测定真菌、尖孢镰刀菌数量及真菌群落组成,并统计发病率和产量。结果表明: 与CK相比,FCK和各RSD处理均能显著降低尖孢镰刀菌数量及其在真菌中的比例,杀菌效果达86.1%～94.6%;AL、AC以及AL+AC处理显著增加了西瓜产量,降低了枯萎病发病率,且枯萎病防控效果分别为63.2%、73.7%和94.7%,而FCK与CK无显著差异。与CK相比,AL和AC处理显著改变了土壤真菌群落组成,FCK处理对真菌群落无显著影响;RSD处理均显著增加了柄孢壳属、假散囊菌、地丝菌、粪盘菌、韦斯特壳属以及久浩酵母菌等优势属的相对丰度,且其中大部分与尖孢镰刀菌数量及其在真菌中的比例以及发病率呈显著负相关关系。综上,低温茬口空闲期的RSD处理可以通过重塑真菌群落组成有效防控西瓜枯萎病的发生。     

Differential induction of heat shock protein genes to the combined treatments of heat with diatomaceous earth,phosphine or carbon dioxide on Plodia interpunctella

Heating is one of the many disinfestation methods commonly used in facilities that store and process agricultural products. In this study, we have investigated whether the combination of heat treatment with diatomaceous earth (DE), phosphine (PH₃) or CO₂ affects the mortality of the wandering larvae of Plodia interpunctella, which is a major pest found in most stored agricultural products. The mortality rate was 35.0% at day 1 after heat treatment at 40°C for 6 h; however, mortality rates increased after combined treatments of heat and 1 ppm DE or 10 ppm PH₃, while 10% CO₂ had no significant effect. Quantitative real‐time PCR analysis showed that combined treatments involving 1 h of heat treatment with either DE, PH₃ or CO₂ increased the mRNA levels of four heat shock protein (hsp) genes (hsp25, hsp70, grp78 and hsp90) in wandering larvae, 1 h post‐treatment, although those rates were slightly differentiated in each heat shock protein. Our results demonstrate that combinations of heat and DE or PH₃ show increased lethality, although insects produce stress responses at the molecular level.     

中国芒果输出蒸热杀虫处理研究

中国芒果输出蒸热杀虫处理研究,包括海南产金煌、爱文、象牙和台农1号4个品种芒果鲜果内橘小实蝇Bactrocera dorsalis(Hendel)的卵和不同龄期幼虫的耐热力试验;芒果小规模、大规模蒸热杀虫处理试验;以及蒸热处理对芒果品质的影响等。结果显示,当蒸热室温度逐步达到50℃,芒果果心温度上升至47℃(使用饱和热蒸汽)并保持这一温度时,在不同处理时间(0、5、10、15、20min)条件下,不同品种芒果内橘小实蝇的耐热力由强至弱的发育期依次为2龄幼虫→3龄幼虫→1龄幼虫→卵,其中以金煌芒果(海南产芒果品种中果体最大,平均重量856g)内2龄幼虫的耐热力最强。完全杀灭海南产金煌芒果内橘小实蝇的卵和幼虫的蒸热条件是果心温度保持在47℃和使用饱和热蒸汽处理20min。金煌芒果的小规模、大规模蒸热杀虫处理试验的结果进一步确认和验证,在上述的蒸热处理条件下,总计数量分别为14000头和35000头最具耐热力的供试橘小实蝇2龄幼虫全部被杀灭(死亡率100%),完全可确保其检疫安全。同时,经蒸热杀虫处理后第7d和第12d的金煌芒果鲜果与对照鲜果品质(包括色泽,以及还原糖、蔗糖、总糖、总酸、维生素C和可溶性固形物的含量)的比较测定数据表明,蒸热温度47℃和使用饱和热蒸汽处理20min,除维生素C的含量有微量损失外,基本可保持鲜果的品质不变。