Identification of sources of resistance to Meloidogyne spp. nematodes in striped Jalapeño pepper (Capsicum annuum L.)

Resumen

Objective. To identify striped Jalapeño pepper plants (Capsicum annuum L.) as a source of genotypes resistant to Meloidogyne enterolobii and Meloidogyne incognita that enable genetic diversification in the development of improved crops within genetic improvement programs.

Design/ Methodology/ Approach. The resistance of 15 accessions of striped Jalapeño peppers native to northern Hidalgo (Mexico) to Meloidogyne enterolobii (Me), and of 12 accessions to Meloidogyne incognita (Mi) were evaluated. The experimental unit was one plant per replicate, with four replicates per accession. Each plant was inoculated with 1000 J2 of Me and Mi obtained through monoxenic selection. The California Wonder (CW) variety was used as a susceptible control against both Meloidogyne species, and the CM-334 line was used as a resistant control against Mi. Resistance was evaluated using the variables number of galls, number of egg masses, number of eggs per gram of root, and reproduction index. Evaluations were performed 34 days-post inoculation (dpi) for Me and 42 dpi for Mi. A randomized complete block design was used in R Studio^©.

Results: Accessions CP922, CP933, CP937, CP938, CP939, and CP946 showed resistance to both species. Whereas accessions CP932, CP903, and CP942 showed specific resistance to Mi, and accessions CP941 and CP935 showed resistance to Me. In particular, the striped Jalapeño accessions CP922, CP933, CP937, CP938, CP939, and CP946 showed evidence of a response range from moderately resistant to highly resistant to both Meloidogyne species.

Limitations/ Implications of the study. This research is an important starting point for identifying intraspecific variation leading to selection for resistance to root-knot nematodes in Jalapeño peppers. At the same time, it constitutes an initial exploratory phase, in which the characterization of this variation does not yet allow for the identification of the physiological, biochemical, or molecular mechanisms that explain the observed resistance. Further research is therefore suggested.

Findings/ Conclusions. The identified accessions represent a promising alternative for use in genetic improvement programs for Capsicum spp., toward resistance to the root-knot nematodes Meloidogyne enterolobii and Meloidogyne incognita. However, for the development of appropriate integrated pest management strategies, it is recommended to incorporate molecular biology, transcriptomics, or methabolomics tools to validate the strategic use of the identified variation.