Genetic control of resistance to soft rot caused by Erwinia carotovora subsp. carotovora in Zantedeschia spp. (Araceae), section Aestivae

The pattern of heredity of resistance to Erwinia carotovora subsp. carotovora in Zantedeschia spp. is investigated. Four species with different resistance levels (Z. albomaculata, Z. elliotiana, Z. pentlandii, Z. rehmannii) were compared to their reciprocal offspring. The occurrence of plastome-genome incompatibility (PGI) affected plant resistance in all families. Therefore, plants that suffered from PGI were omitted from genetic analyses. Resistance was quantitative and the correlation between resistance levels of parents and offspring (h2= 0.33;r2= 0.66) indicated a genetic basis of resistance. Z. rehmannii and Z. albomaculata contributed more resistance genes than Z. elliotiana or Z. pentlandii. Transgression among some of the offspring of Z. rehmannii and Z. albomaculata indicated the presence of complementary resistance genes in these two species and good potential for resistance breeding.