Abstract
Several root-knot nematode ( Meloidogyne spp.) resistance genes have been discovered in different stone fruit crops. However, none of them has yet been cloned and they were only located on the chromosomes. In this study, a candidate root-knot nematode resistance gene (designated as psoRPM1) was isolated from the individual plant of Xinjiang wild myrobalan plum ( Prunus sogdiana ) by degenerate PCR amplification combined with the RACE technique. The gene had a typical NBS-LRR structure and high homology with Mi-1.2 (root-knot nematode resistance genes in tomato). The expression of psoRPM1 gene increased in the roots of resistant wild myrobalan plum material 12, 24 and 48 h after inoculation with root-knot nematodes and the expression of psoRPM1 gene was maximum 12 h after inoculation. But in susceptible plant, the psoRPM1 gene expression remained low both before and after inoculation. This result suggested that the psoRPM1 gene was constitutively expressed gene in the wild myrobalan plum. In-situ hybridization results showed that the psoRPM1 gene mainly expressed in both phloem and cortex parenchyma of root 12 h after inoculation in resistant plant. Furthermore, the psoRPM1 gene only expressed in phloem 48 h after inoculation in resistant plant. The result suggested that the psoRPM1 gene played a role in keeping nematodes off the cortex when nematodes began to infect the plant’s roots. After root-knot nematodes entering into cortex parenchyma, the psoRPM1 gene mainly played defense function in phloem of pericycle. Using the gene gun bombarding into onion epidermal cells, the result was that psoRPM1 protein was located in cytomembrane and might be interacted with other proteins in cytomembrane to locate Key words: Xingjiang wild myrobalan plum (Prunus sogdiana), root-knot nematodes (Meloidogyne incognita), gene, in-situ, gene location.
Highlights
The root-knot nematode (Meloidogyne spp.) is a sedentary parasite of plant roots in many economically important cropping systems where they cause severe yield loss (Williamson and Hussey, 1996)
The most rootstock material is susceptible to root-knot nematodes (RKN) and resistance sources have been sought with the objective of controlling these pests (Kochba and Spiegel-Roy, 1972; Kester and Grassely, 1987; Nyczepir, 1991)
Among them the myrobalan plum accession P.2175 is highly resistant to all tested RKN species (M. incognita, Meloidogyne arenaria, Meloidogyne javanica, Meloidogyne floridensis, and Meloidogyne mayaguensis) (Rubio-Cabetas et al, 1999), a trait conferred by the major dominant gene Ma
Summary
The root-knot nematode (Meloidogyne spp.) is a sedentary parasite of plant roots in many economically important cropping systems where they cause severe yield loss (Williamson and Hussey, 1996). The primary methods to control root-knot nematodes are crop rotation (Dong et al, 2007), soil fumigation (Bridge, 1996) and chemicals (Onifade et al, 2008). These technologies for nematode control have left much to be desired, such as fumigation. Cultivars resistant to root-knot nematodes can potentially reduce environmental pollution and toxic systemic nematicides are unnecessary as they won’t be an efficient and durable control method (Djian-Caporalino et al, 1999).
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