Detection of Mi-1.2 gene for resistance to root—knot nematode in tomato—breeding lines developed for resistance to begomovirus in Morocco

A PCR based method was developed to detect the Mi-1.2, a resistant gene to root—knot nematode, in begomovirus—resistant breeding lines developed in Morocco. Two—step PCR protocol were tested on 14 experimental resistant tomato breeding lines developed in Morocco and known resistant and susceptible cultivars. The first PCR—step involved the PCR primers (PM3Fb/PM3Rb) specific for the region 3′ of the Mi-1.2 and REX primers. Every plant DNA tested gave a 720-bp fragment for the REX primers, but only those plants with Mi-1.2 gene gave a 500-bp fragment with PM3Fb/PM3Rb primers. To distinguish the heterozygous genotypes for the Mi-1.2, a second PCP—step was used with primers (PMiF3/PMiR3). All the 14 tested tomato breeding lines developed in Morocco have the Mi-1.2 gene, and thus should be resistant to root—knot nematode. Nine of them are homozygous (Lp.-Mi-1/Lp.-Mi-1) and the others are heterozygous plants with Lp-Mi-1/Ih902-Mi-1 genotype.