Abstract: Abstract：Single PCR reaction with two SCAR markers respectively tightly linkedwith M／an d Sw一5 genes in tomato，which resistant to root—knot nema tode an d toma to spotted wi lt virus，has been used to screen the multiplex
ban ds．The PCR products with multiplex primers were completely correspond to the amplified bands produced by single SCAR primer．Among them，codominant SCAR 1 Balker tightly linked with Mi gene produce 750 bp flag—
ment in both resistant an d susceptible toma to lines．Th e am plified ban ds from susceptible an d resistant lines were distinguishable after cleavage wi th the restriction enzyme I． Genotype wi th homozygous an d heterozygous M ／
gene could produce respectively 570 bp， 160 bp an d 750， 570 bp， 160 bp bands ． Susceptible genotypes still present 750 bp fragment．The dominant SCAR2 marker tightly linked with Sw一5 gene would produce only 400 bp PCR product in resistant genotype． Th e replicated stable results pmved that tw o resistant genes could be identified simultaneously by using corresponding SCAR primer under adaptable condition．This system compared with single
primerPCR would be time saving， less labor an d low cost． It could be very useful for marker—as sisted selection during early stage in tommo and fficiently speed up breed ing procedure．

Key words: Tomato, PCR, M／gene, Sw一5 gene