Identification and inheritance of a new source of resistance against Tomato spotted wilt virus (TSWV) in Capsicum

Abstract

Tomato spotted wilt virus (TSWV) is an important viral disease affecting pepper production worldwide. A single dominant resistance gene, Tsw, originating from Capsicum chinense has been identified and utilized during the last several decades. However, there have been reports that Tsw resistance can be overcome by new field isolates of TSWV. This has necessitated the identification of a new source of resistance. Here, a set of pepper germplasm collections comprising 487 accessions from six Capsicum species and 30 commercial F1 hybrids was evaluated for resistance to TSWVPap. A new resistance source, C. chinense ‘AC09-207’, was identified and characterized. Genetic analysis showed that the resistance in C. chinense ‘AC09-207’ was conferred by a single dominant gene. The resistance responses of ‘AC09-207’ were compared with other known resistance sources. The timing and number of necrotic response were similar to C. chinense ‘PI152225’, whereas the premature abscission of inoculated cotyledons and leaves were significantly different from other resistance sources, ‘PI152225’ and ‘PI159236’. To compare genome locations between the new resistance gene and Tsw, an allelism test was conducted. No recombinants were found in all F1, F2 and reciprocal backcross populations derived from the new resistance source and three known resistance sources (‘PI152225’, ‘PI159236’, and ‘PI159234’) demonstrating that the new resistance gene may be a unique allele at the Tsw locus or be controlled by a different gene tightly linked to Tsw.