Pan-plastome approach empowers the assessment of genetic variation in cultivated Capsicum species

Abstract

Abstract Pepper species (Capsicum spp.) are widely used as food, spice, decoration, and medicine. Despite the recent old-world culinary impact, more than 50 commercially recognized pod types have been recorded worldwide from three taxonomic complexes (A, B, and P). The current study aimed to apply a pan-plastome approach to resolve the plastomic boundaries among those complexes and identify effective loci for the taxonomical resolution and molecular identification of the studied species/varieties. High-resolution pan-plastomes of five species and two varieties were assembled and compared from 321 accessions. Phyloplastomic and network analyses clarified the taxonomic position of the studied species/varieties and revealed a pronounced number of accessions to be the rare and endemic species, C. galapagoense, that were mistakenly labeled as C. annuum var. glabriusculum among others. Similarly, some NCBI-deposited plastomes were clustered differently from their labels. The rpl23-trnI intergenic spacer contained a 44 bp tandem repeat that, in addition to other InDels, was capable of discriminating the investigated Capsicum species/varieties. The rps16-trnQ/rbcL-accD/ycf3-trnS gene set was determined to be sufficiently polymorphic to retrieve the complete phyloplastomic signal among the studied Capsicum spp. The pan-plastome approach was shown to be useful in resolving the taxonomical complexes, settling the incomplete lineage sorting conflict and developing a molecular marker set for Capsicum spp. identification.