Molecular mapping of dominant gene responsible for leaf curl virus resistance in chilli pepper (Capsicum annuum L.)

Abstract

A resistant source (S-343) having monogenic dominant resistance to chilli leaf curl virus disease (ChiLCVD) has been identified at Punjab Agricultural University (PAU), Ludhiana. The F₂ mapping population of 204 plants was derived from the cross MS-341 (susceptible) × S-343 (resistant) to identify the linked marker with the disease-resistant gene. Out of the 685 single-sequence repeats (SSRs) used, only 160 primers showed parental polymorphism. These 160 polymorphic primers were used for bulk segregant analysis and only eight SSR primers were able to differentiate the resistant and susceptible bulks. The linkage analysis revealed that the two markers CA 516044 and PAU-LC-343-1 were found linked with the disease-resistant gene covering a total distance of 15.7 centimorgan (cM). The two primers CA 516044 and PAU-LC-343-1 were found located on chromosome 6 of the pepper genome at a genetic distance of 6.8 cM and 8.9 cM, respectively, from the resistant gene. The validation of linked markers was performed using 26 resistant and susceptible genotypes developed at PAU, Ludhiana by former researchers. The validation of the primers revealed that there was a correlation between phenotypic and genotypic data of the used genotypes, and these markers can be used for the marker-assisted breeding procedures for transferring ChiLCVD resistance until the gene-based markers will be developed. The markers described in this study are the first-ever molecular markers identified as linked to the ChiLCVD-resistant gene.

Keywords: Capsicum annuum; Dominant gene; Leaf curl virus; Molecular mapping; Resistance; SSRs.

Fig. 1

Plants of the two parents MS-341 (left) and S-343 (right) during their field growth stage. Symptoms of ChiLCVD can be easily seen on MS-341 (susceptible), while the symptoms are not seen on S-343 (resistant)

Fig. 2

Variation in the symptoms of chilli leaf curl virus disease in the plants of F₂ population during artificial screening at nursery stage. (1) Mild puckering of 1–2 leaves. (2) Upward curling and cupping of leaves. (3) Yellowing of interveinal areas and upward curling of leaves. (4) Clearing of veins and yellowing of interveinal areas. (5) Downward and upward curling, inward rolling of the leaves, clearing of veins, and yellowing of interveinal areas

Fig. 3

Percent proportion of plants with different disease grades in an F₂ population of 204 plants

Fig. 4

Schematic representation of development of F₂ mapping population for genotyping and F_2:3 for the confirmation of genetics of resistance

Fig. 5

Genotyping of F₂ individuals by primer CA 516044. Here, P₁: MS 341 (Susceptible parent), P₂: S-343 (resistant parent), A: MS-341 type, B: S-343 type, and H: Heterozygous between A/B

Fig. 6

Genotyping of F₂ individuals by primer PAU-LC-343-1. Here, P₁: MS 341 (Susceptible parent), P₂: S-343 (resistant parent), A: MS-341 type, B: S-343 type, and H: Heterozygous between A/B

Fig. 7

Linkage map of the disease-resistant gene and SSR markers CA 516044 and PAU-LC-343-1 using MapMaker 3.0 software

Fig. 8

Validation of primer CA 516044 using resistant and susceptible chilli genotypes developed at Punjab Agricultural University, Ludhiana

Fig. 9

Validation of primer PAU-LC-343-1 using resistant and susceptible chilli genotypes developed at Punjab Agricultural University, Ludhiana