McKenry Michael V, Anwar Safdar A
Nematologist, University of California, Department of Nematology, River side, CA 92521 HEC-Foreign Professor, University of Agriculture, Faisalabad, Pakistan.
J Nematol. 2007 Mar;39(1):50-4.
Harmony grape rootstock displays resistance to several Meloidogyne spp. but that resistance is not durable in commercial vineyard settings. A 2-year experiment in a microplot setting revealed host specificities of two virulent populations of Meloidogyne arenaria and an avirulent population of Meloidogyne incognita. In a subsequent split-root experiment, the avirulent nematode population was demonstrated to induce resistance to the virulent nematode population. To quantify the level of resistance, reproduction of the virulent nematode population was determined 63 days after being challenged by an avirulent nematode population using a range of inoculum densities and timeframes. Induction of resistance became apparent when the virulent nematode population was inoculated 7 days after the avirulent nematode population and increased thereafter. The level of induced resistance increased with increased inoculum levels of the avirulent nematode population. Root systems of perennial crops are commonly fed upon simultaneously by multiple nematode species. These two studies indicate that field populations can become preferentially virulent upon one or multiple rootstocks and that co-inhabiting populations may induce existing resistance mechanisms. In perennial crops, it is common for numerous nematode species besides Meloidogyne spp. to be present, including some that feed without causing apparent damage.
和谐葡萄砧木对几种根结线虫表现出抗性，但在商业葡萄园环境中这种抗性并不持久。在微小区环境中进行的一项为期两年的实验揭示了南方根结线虫的两个致病种群和南方根结线虫的一个无致病力种群的寄主特异性。在随后的分根实验中，无致病力的线虫种群被证明能诱导对致病力线虫种群的抗性。为了量化抗性水平，在使用一系列接种密度和时间框架受到无致病力线虫种群攻击63天后，测定致病力线虫种群的繁殖情况。当致病力线虫种群在无致病力线虫种群接种7天后接种时，抗性诱导变得明显，并在此后增强。诱导抗性水平随着无致病力线虫种群接种水平的增加而提高。多年生作物的根系通常会同时受到多种线虫物种的侵害。这两项研究表明，田间种群可能会对一种或多种砧木优先表现出致病力，并且共同存在的种群可能会诱导现有的抗性机制。在多年生作物中，除了根结线虫属外，通常还存在许多线虫物种，包括一些取食但不会造成明显损害的线虫。
