Liu Chang, Timper Patricia, Ji Pingsheng, Mekete Tesfamariam, Joseph Soumi
Department of Plant Pathology, University of Georgia, Tifton, GA 31793.
USDA ARS, Tifton, GA 31793.
J Nematol. 2017 Sep;49(3):304-310.
The bacterium is a parasite of root-knot nematodes ( spp.). Endospores of attach to the cuticle of second-stage juveniles (J2) and subsequently sterilize infected females. When encumbered by large numbers of spores, juveniles are less mobile and their ability to infect roots is reduced. This study looked at different factors that influence spore attachment of to the root-knot nematode . Pretreatment of J2 with root exudates of eggplant ( cv. Black beauty) reduced spore attachment compared with pretreatment with phosphate-buffered saline (PBS), suggesting that the nematode surface coat was altered or the spore recognition domains on the nematode surface were blocked. Spore attachment was equally reduced following exposure to root exudates from both host and nonhost plants for , indicating a common signal that affects spore attachment. Although phytohormones have been shown to influence the lipophilicity of the nematode surface coat, auxins and kinetins did not affect spore attachment compared with PBS. Root exudates reduced spore attachment more in sterilized soil than in natural soil. Sterilization may have eliminated microbes that consume root exudates, or altered the chemical components of the soil solution or root exudates. Root exudates caused a greater decrease in spore attachment in loamy sand than in a sandy loam soil. The sandy loam had higher clay content than the loamy sand, which may have resulted in more adsorption of compounds in the root exudates that affect spore attachment. The components of the root exudates could have also been modified by soil type. The results of this study demonstrate that root exudates can decrease the attachment of endospores to root-knot nematodes, indicating that when these nematodes enter the root zone their susceptibility to spore attachment may decrease.
该细菌是根结线虫（ spp.）的寄生虫。 的内生孢子附着在二龄幼虫（J2）的角质层上，随后使受感染的雌虫绝育。当被大量孢子阻碍时，幼虫的活动能力降低，其感染根部的能力也会下降。本研究考察了影响 孢子附着于根结线虫 的不同因素。用茄子（品种：黑美人）的根系分泌物预处理J2，与用磷酸盐缓冲盐水（PBS）预处理相比，孢子附着减少，这表明线虫表面涂层发生了改变，或者线虫表面的孢子识别域被阻断。暴露于宿主植物和非宿主植物的根系分泌物 后，孢子附着同样减少，这表明存在影响孢子附着的共同信号。尽管植物激素已被证明会影响线虫表面涂层的亲脂性，但与PBS相比，生长素和激动素并不影响孢子附着。根系分泌物在灭菌土壤中比在天然土壤中更能减少孢子附着。灭菌可能消除了消耗根系分泌物的微生物，或改变了土壤溶液或根系分泌物的化学成分。根系分泌物在砂壤土中比在砂质壤土中导致孢子附着的减少更大。砂质壤土的粘土含量高于砂壤土，这可能导致更多影响孢子附着的根系分泌物中的化合物被吸附。根系分泌物的成分也可能因土壤类型而改变。本研究结果表明，根系分泌物可减少 内生孢子对线结线虫的附着，这表明当这些线虫进入根区时，它们对孢子附着的敏感性可能会降低。
