Resistance to the root knot nematode Meloidogyne incognita in different tomato genotypes based on screening and cloning studies

Resistance in different genotypes of tomato to Meloidogyne incognita were studied using screening and molecular studies. Lycopersicon peruvianum , a wild species of tomato showed resistance reaction to Meloidogyne incognita under artificial screening infection studies. L. peruvianum , showed least penetration rate of one nematode. In susceptible wild species L. pimpinellifolium , varieties and hybrid, feeding sites were characterized by giant cells containing granular cytoplasm and many hypertrophied nuclei. In L. peruvianum , the vascular tissues were not disturbed and epidermal layer showed lignin bodies which have accumulated and inhibited the nematodes into the roots. RT-PCR analysis to detect presence of resistance (R) gene showed a 877 bp amplicon present only in L. peruvianum . Sequence analysis of the partial cDNA from L. peruvianum showed considerable homology with already available disease resistance gene against Meloidogyne incognita . These results have important consequences in terms of transformation strategies to develop root knot nematode resistant transgenic plants