Evidence of a new gene for high resistance to <i>Meloidogyne</i> spp. in Myrobalan plum, <i>Prunus cerasifera</i>

Abstract

Abstract The Myrobalan plum Prunus cerasifera clones ‘P,2175’ and ‘P,1079’ carry single major genes ( Ma1 and Ma2 . respectively) for resistance to the predominant root–knot nematode (RKN) species Meloidogyne arenaria (MA), Meloidogyne incognita (MI) and Meloidogyne jaranica (MJ). The Myrobalan plum clone ‘P.2980’ is another complete–spec–trum source bearing favourable agronomic features. The genetics of its resistance to MA, MI, MJ and to the population Meloidogyne sp. Florida has been investigated from G1 crosses with the host Myrobalan plum clone ‘P.16.5’ (recessive for both Ma genes), the resistant clone ‘P.2175’ (heterozygous for Mal ) and the ‘Nemared’ peach (homozygous for resistance to MA, MI and MJ but a host for M . sp. Florida). The segregation of the Gl hybrids from the intraspecific crosses into two significantly separated resistant and host classes, independent of the RKN species, indicates that resistance to all four species in ‘P.2980’ is also controlled by a single major dominant (heterozygous) gene. This gene is designated Ma3 because it shares the same spectrum and efficiency as Ma1 and Ma2 , and its relationship with these last two genes is discussed. The first hybrids between ‘P.2980’ and ‘Nemared’ tested only segregated for resistance to M . sp. Florida. These results illustrate the possibility of cumulating (pyramiding) Ma3 and the ‘Nemared’ peach resistance gene(s) into new interspecific rootstocks.