Characterization of the RMja resistance gene to root-knot nematodes from the 'Alnem' almond rootstock
In Prunus spp., resistance (R) genes to RKNs with different spectra have been identified and mapped in plum (Ma), peach (RMia) and almond (RMja). The two genes Ma and RMia have been identified and located on the Linkage groups 7 and 2. In order to identify the RMja gene of the Alnem rootstock released by Kochba and Spiegel-Roy (1976), we have created a population Lauranne × Alnem (LA) and we have done a fine mapping study on this LA population. Hybrids were tested in greenhouse for their resistance to Meloidogyne javanica and we could map the RMja resistance gene on the LG7 (linkage group) region between the two SSR markers CPPCT039 and CPPCT022. In a second step, the genome of the two parents Lauranne and Alnem were assembled by NGS sequencing and mapping on the V2 reference peach genome. We observed that the peach gene Prupe.7G065400 in this located RMja region was well aligned in Alnem with a similar TNL gene which could be the RMja gene. We constructed an Alnem BAC library in order to obtain the whole sequence of the RMja DNA region using PacBio technology and to validate if the candidate gene of RMja is really the orthologue of Prupe.7G065400. Finally, for using MAS (marker assisted selection) to screen this candidate RMja gene, we designed two Kasp® markers from a specific SNP between the resistant parent Alnem and other susceptible almond cultivars.
Duval, H., Van Ghelder, C., Callot, C. and Esmenjaud, D. (2018). Characterization of the RMja resistance gene to root-knot nematodes from the 'Alnem' almond rootstock. Acta Hortic. 1219, 325-330
Prunus rootstock, almond, RKN nematodes, resistance gene, Kasp® marker