Articles
ROOT KNOT NEMATODE RESISTANCE IN MYROBALAN PLUM. INHERITANCE AND ROOTSTOCK BREEDING PERSPECTIVES USING MARKER-ASSISTED SELECTION
Among the new objectives, resistance to root-knot nematodes (RKN), Meloidogyne spp, is a major aspect which concerns several fruit species, i.e. peach, diploid plum species, almond and apricot.
We revealed resistance sources within the myrobalan plum, P. cerasifera.
The genetic study of resistance to Meloidogyne was developed from a diallel system of crosses composed of seven cerasifera parents.
Two parents were highly resistant to all the Meloidogyne species, even at high temperatures and under high levels of inoculum pressure.
The other five were sensitive.
The genetic analysis developed from F1 progeny (G1) and from back-crosses (G2) showed that the resistance to M. arenaria is monogenic and dominant.
Moreover this dominant gene (Ma) is responsible for the resistance towards the other Meloidogyne species, incognita and javanica and also towards the virulent population « Floride », as shown by a further study.
More recently, a molecular approach (RAPD and AFLP) and the use of BSA (Bulk Segregant Analysis) allowed us to define a few markers for the resistance gene in the species cerasifera.
Our new rootstock breeding programme initiated through a European Union project aims at associating the myrobalan resistance gene (Ma) with the gene(s) of the peach Nemared or Nemaguard, in order to prevent any possible break down of the resistance by new virulent stocks.
In the near future, molecular markers of both genes will be a useful tool to assist selection.