Selection strategy of a Coffea canephora rootstock with simultaneous nematode resistance to Meloidogyne exigua, M. incognita and M. paranaensis

Abstract

The cultivars of most Brazilian Arabica coffee plantations are susceptible to root knot nematodes (RKN), Meloidogyne spp. By planting resistant rootstocks of the species Coffea canephora, a successful strategy in some producing regions, coffee can be cultivated in RKN-infested areas. However, the only currently available rootstock cultivar in Brazil has a segregation rate close to 20% for susceptibility. To breed new rootstock cultivars resistant to the main RKN species, with a lower segregation rate, 10 C. canephora clones were selected in areas infested by these nematodes, with confirmed resistance to Meloidogyne exigua, M. incognita and M. paranaensis, under controlled conditions. The genetic compatibility analysis of the clones detected only one incompatible combination (CcK1xCcR5 and its reciprocal). Almost all F1 hybrids resulting from the cross between the selected clones were resistant to M. exigua and M. incognita. According to the reproduction factor, 77% of the evaluated F1 hybrids proved resistant to M. paranaensis, and those classified as susceptible had variable segregation rates within the progeny, generally lower than 25%. Based on these data, different hybrid combinations can be suggested for the development of new rootstock cultivars of C. canephora with simultaneous resistance to coffee RKN. This approach has immediate practical applications in grafting Arabica coffee scion cultivars in areas where nematodes restrict cultivation.