Allelic relationships between genes for resistance to tomato spotted wilt tospovirus in Capsicum chinense

• Published in: Theoretical and applied genetics Vol. 90; no. 1; p. 146
• Main Author: Boiteux, L.S. (Centro Nacional de Pesquisa de Hortalicas, Brasilia (Brazil). EMBRAPA)
• Format: Journal Article
• Language: English
• Published: Germany 1995
• Subjects: CAPSICUM CHINENSE; Gartenbau; GENE; GENES; GENETICA; Genetics; GENETIQUE; HEREDITE; HERENCIA GENETICA; Pepper; Pflanzenzuechtung; RESISTANCE AUX MALADIES; Resistance gene; RESISTENCIA A LA ENFERMEDAD; Tomato spotted wilt virus; Tospoviruses; VIRUS DE LAS PLANTAS; VIRUS DES VEGETAUX
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/BF00221009

Pepper (Capsicum chinense Jacq.) has been reported to be an important reservoir of resistance genes to tomato spotted wiltvirus (TSWV). The genes for TSWV resistance present in three C. chinense lines ('PI 152225', 'PI 159236' and 'Panca') were investigated for allelism. All resistant lines were crossed with each other. Parents, F1 backcrosses and F2 populations (including reciprocals) developed from those crosses were mechanically inoculated with a highly virulent TSWV isolate. Susceptible C. annuum cv 'Magda' was used to check inoculum virulence. Fifty plants of the F1 hybrids; 'Magda' x 'PI 152225', 'Magda' x 'PI159236', and 'Magda' x 'Panca, were also inoculated with the TSWV isolate. The resistance response in all C. chinense sources was associated with a localized, hyper sensitive-like reaction that was phenotypically expressed as a prompt formation of large local lesions accompanied by premature leaf abscission. All F1 generations presented a final score of resistant; indicating that the expression of resistance to TSWV is conditioned by a dominant gene regardless of the source. The absence of segregation for resistance to TSWV that was observed in all generations of the crosses between C. chinense lines indicated that either a tightly linked group of genes exists or that the resistance is governed by the same single major gene (probably the already described Tswgene). Previous reports have indicated that the Tsw gene is not effective against tospovirus members of serogroup 2, i.e. tomatochlorotic spot virus (TCSV) and groundnut ring spot virus (GRSV). In the assay described here, all of the C. chinense lines showed, after mechanical inoculation, an identical susceptibility response to the TCSV and GRSV isolates.