Meza Pablo, Soto Braulio, Rojas Luis, Esmenjaud Daniel
Instituto de Investigaciones Agropecuarias, Centro Regional La Platina, La Pintana, Santiago, Región Metropolitana, Chile.
ISA, INRA, Université de Nice-Sophia Antipolis, CNRS, 06900 Sophia Antipolis, France.
Plant Dis. 2016 Jul;100(7):1358-1363. doi: 10.1094/PDIS-11-15-1331-RE. Epub 2016 Apr 21.
Root-knot nematodes (RKN; Meloidogyne spp.) are predominant polyphagous pests of crops in the Central Valley of Chile. Twenty RKN populations from this region were collected from diverse crops and subsequently identified with both sequence-characterized amplified region and isoenzyme markers. Populations included three RKN species: Meloidogyne ethiopica (75%), M. javanica (15%), and M. arenaria (10%). This is the first report of the high prevalence and wide host range of M. ethiopica in Chile. The host status of three Prunus rootstocks for isolates obtained from the Chilean RKN populations was then evaluated. Rootstocks assessed included the peach rootstock Nemaguard and the plum rootstock Marianna 2624, both previously considered resistant, and the peach rootstock Pomona as a susceptible accession. In the first experiment, rootstocks were inoculated individually in pots with 10,000 second-stage juveniles and eggs of each isolate, and reproduction and galling were evaluated 5 months after inoculation. In the second experiment, the six most aggressive RKN isolates were used in a mixture to evaluate the host response of the same three rootstocks. No RKN were detected on Marianna 2624 in both experiments, which confirmed its immune host status to M. arenaria and M. javanica; this is the first report of immunity to M. ethiopica. Even though Pomona was classified overall as susceptible, the response of this rootstock to the RKN isolates was highly variable and ranged from susceptible to resistant, depending on the RKN isolates. Nemaguard ranged from resistant (to each of the most aggressive isolates and to their mixture) to highly resistant (to M. arenaria isolates). Our results illustrate that Prunus rootstocks express different levels of resistance to RKN species. RKN resistance may be active either at the isolate level (as in Pomona), at the species level (as in Nemaguard toward M. javanica and M. arenaria), or at the genus level (as in Marianna 2624).
根结线虫（RKN；Meloidogyne属）是智利中央山谷地区主要的多食性作物害虫。从该地区不同作物上采集了20个根结线虫种群，随后利用序列特征扩增区域和同工酶标记进行鉴定。这些种群包括三种根结线虫：埃塞俄比亚根结线虫（75%）、爪哇根结线虫（15%）和花生根结线虫（10%）。这是埃塞俄比亚根结线虫在智利高流行率和广泛寄主范围的首次报道。然后评估了三种李属砧木对从智利根结线虫种群中获得的分离物的寄主状态。评估的砧木包括桃砧木Nemaguard和李砧木Marianna 2624，这两种砧木之前都被认为具有抗性，以及作为感病品种的桃砧木Pomona。在第一个实验中，将砧木分别种植在花盆中，每株接种10000条每种分离物的二龄幼虫和卵，并在接种5个月后评估繁殖情况和虫瘿形成情况。在第二个实验中，使用六种最具侵袭性的根结线虫分离物混合接种，以评估相同三种砧木的寄主反应。在两个实验中，Marianna 2624上均未检测到根结线虫，这证实了其对花生根结线虫和爪哇根结线虫的免疫寄主状态；这是对埃塞俄比亚根结线虫免疫的首次报道。尽管Pomona总体上被归类为感病品种，但该砧木对根结线虫分离物的反应高度可变，从感病到抗病不等，这取决于根结线虫分离物。Nemaguard的抗性范围从（对每种最具侵袭性的分离物及其混合物）抗性到（对花生根结线虫分离物）高抗。我们的结果表明，李属砧木对根结线虫物种表现出不同程度的抗性。根结线虫抗性可能在分离物水平（如Pomona）、物种水平（如Nemaguard对爪哇根结线虫和花生根结线虫）或属水平（如Marianna 2624）上起作用。
