Genetic analysis of pod and seed resistance to pea weevil in a Pisum sativum x P. fulvum interspecific cross

Interspecific populations derived from crossing cultivated field pea, Pisum sativum, with the wild pea relative, Pisum fulvum, were scored for pod and seed injury caused by the pea weevil, Bruchus pisorum. Pod resistance was quantitatively inherited in the F(2) population, with evidence of transgressive segregation. Heritability of pod resistance between F(2) and F(3) generations was very low, suggesting that this trait would be difficult to transfer in a breeding program. Seed resistance was determined for the F(2) population by testing F(3) seed tissues of individual F(2) plants and pooling data from seed reaction for each F(2) plant (inferred F(2) genotype). Segregation for seed resistance in the F(2) population of the cross Pennant/ATC113 showed a trigenic mode of inheritance, with additive effects and dominant epistasis towards susceptibility. Seed resistance was conserved over consecutive generations (F(2) to F(5)) and successfully transferred to a new population by backcross introgression. Seed resistance in the backcross introgressed population segregated in a 63 : 1 ratio, supporting the three-gene inheritance model. It is proposed that complete resistance to pea weevil is controlled by three major recessive alleles assigned pwr(1), pwr(2), and pwr(3), and complete susceptibility by three major dominant alleles assigned PWR(1), PWR(2), and PWR(3). It is recommended that large populations (> 300 F(2) plants) would be required to effectively transfer these recessive alleles to current field pea cultivars through hybridisation and repeated backcrossing.