Inheritance of resistance to root-knot nematode (Meloidogyne incognita race 1) in tomato (Solanum lycopersicum L.) ‘Pusa 120’

Abstract

SummaryThe inheritance of resistance to root knot nematode (RKN; Meloidogyne incognita race 1) in progeny of the tomato (Solanum lycopersicum L.) cultivar ‘Pusa 120’ was studied.Twenty-eight diverse genotypes of tomato were screened for resistance against M. incognita (race 1). Two susceptible tomato genotypes (‘La-Bonita’ and ‘Selection N-5’) used as pollen donors, were crossed with the more resistant ‘Pusa 120’ as the seed parent to obtain F1 and F2 generations, and two backcross generations.After 60 d of exposure, the numbers of root knots and egg masses per plant root system were counted. A chi-square ( χ2) test of the frequency distribution based on the root-knot index (RKI) of the F2 progenies of the two crosses (resistant × susceptible) showed the best-fit to a 3(R):1(S), Mendelian ratio. The monogenic dominant model was further confirmed by the 1(R):1(S) ratio found to be the best-fit for the backcross generation (B2) with the susceptible pollen donor parent. These results confirmed that resistance to RKN (M. incognita race 1) is controlled by a single dominant resistance gene (R-gene) inherited from the resistant parent, ‘Pusa 120’. ‘Pusa 120’ can therefore be used to develop high yielding varieties, or hybrids, of tomato with improved RKN resistance.