We took part in a study which led us to the conclusion that linkage exists between Tm-2 and resistance to Fusarium oxysporum f. sp. radicis lycopersici (= FORL) (Elkind et al. , 1988). Since then, in addition to the lines carrying Tm-2 originating from L. peruvianum PI 126926, we have found to be resistant line B 2162 (origin: C.D. Clayberg, seeds received from the Glasshouse Crops Research Institute, Littlehampton, U.K., in 1962), which carries Tm-2 linked to nv and which has been derived from a complex cross including L. peruvianum. The linkage between Tm-2 and the resistance to FORL is not absolute, as several lines with Tm-2 were found to be susceptible to FORL in our tests.
Lines of Tm-2^2^ were studied in the same series of tests, using artificial inoculation with French FORL isolates. Several of these lines were found to be resistant to FORL, including the INRA Momor line (Laterrot, 1987). This line is derived rom a breeding program carried out on 15 backcrosses starting with lien 630818 received from L.J. Alexander in 1964 and which originates from L. peruvianum PI 128650.
As could be expected, line 630818 was shown to be resistant to FORL. As the line has been widely used as a source of Tm-2^2^, it is probable that many lines which are resistant to TMV are also resistant to FORL and that, in consequence, certain F1 hybrids which carry the Tm-2^2gene^ may also be resistant to FORL. It would therefore be advisable to encourage breeders to test in relation to FORL both their Tm-2^2^and their Tm-2 material.
Including IRB301-31, the Japanese genitor of FORL resistance, resistance to FORL has been found in lines derived from four different sources of L. peruvianum. It is impossible to say yet whether all lines which are resistant to FORL carry the same gene as the IRB 301-31, gene for which the symbol Fr-1 was proposed by D.J. Vakalounakis (1988).
Literature Cited:
Elkind et al. 1988 TGC Report 38:22.
Laterrot, H. 1987 TGC Report 37:91.
Vakalounakis, D.J. 1988 Plant Pathology 37:71-73.