Molecular and morphological characterization of EMS-induced chili pepper mutants resistant to Chili veinal mottle virus

Manzila I, Priyatno TP, Nugroho K, Terryana RT, Lestari P, Hidayat SH. 2020. Molecular and morphological characterization of EMS-induced chili pepper mutants resistant to Chili veinal mottle virus. Biodiversitas 21: 1448-1457. Chili veinal mottle virus (ChiVMV) is a major prevalent virus that potentially reduces the yield of chili pepper by more than 50% in Indonesia. Therefore, the development of a ChiVMV-resistant cultivar is necessary to ensure satisfactory chili pepper production. Mutation breeding is a promising tool available to produce virus-resistant plants via the induction of new alleles due to point mutations within the existing chili germplasm. This research was conducted to assess the genetic variation of ten promising (M6) EMS-induced mutant lines of chili pepper (Capsicum annuum L.) potentially resistant to ChiVMV by their morphological characteristics and SSR profile, as well as identify potential mutants based on agronomic traits. The ten chili pepper mutant lines used in the present study were derived from the shoot tips of a Gelora cultivar treated with 0.5% ethyl methanesulfonate (EMS) as a chemical mutagen. The performance of the respective promising chili pepper mutant lines both at a molecular and morphological level was observed. Phenotypic analysis showed that all the promising chili pepper mutant lines underwent significant morphological changes. Of these, the phenotype coefficient variation (PCV) values were higher than the genotype coefficient variation (GCV) values for all the traits observed. High heritability (h2) was found for the canopy area, length of the fruit stalk, fruit weight, fruit weight per plant, thick fruit flesh, leaf width, leaf length, and fruit storage duration. A total of 52 alleles were detected from the five polymorphic SSR loci with 5.2 average alleles/loci. A dendrogram was generated and revealed two groups with five mutants clustered separately from their parents which could be valuable for further improvement.

Serological, Molecular, and Pathotype Diversity of Pepper veinal mottle virus and Chili veinal mottle virus

Variability within the pepper-infecting potyviruses Pepper veinal mottle virus (PVMV) and Chili veinal mottle virus (ChiVMV) in Africa and Asia was investigated. Coat protein (CP) gene sequence diversity revealed three clades that corresponded to three geographic locations and there was no evidence of presence of the ChiVMV/Asian group in western or central Africa. These clades included closely related isolates that potentially belong to two viral species, which is consistent with current nomenclature. These clades could not be unambiguously identified with polyclonal antisera; however, reverse transcription-polymerase chain reactions allowed differentiation of the isolates into two species based on a large indel in the CP gene. PVMV and ChiVMV isolates were classified into three and two pathotypes, respectively, in relation to pepper genotypes carrying different resistance factors. Specificity of resistance only partially corresponded to molecular diversity of the isolates. Only one isolate of PVMV could infect pepper genotypes carrying the two recessive genes pvr6 and pvr2 2; however, these genotypes were not infected by PVMV in field trials in Senegal, despite a high prevalence of PVMV in the surrounding pepper plants.