Characterisation of three Capsicum species and their phylogenetic relationship

Abstract

Taxonomical confusion is known to exist in the genus Capsicum due to the considerable genetic variability among the members. The characterisation and understanding of the genetic relationship among the Capsicum species are therefore important in their breeding programme. This study employed morphological, anatomical, cytological and electrophoretic studies to characterise and elucidate the phylogenetic relationship that exists among the species studied namely: Capsicum annuum var annuum, C. frutescens and C. chinense. The cluster analysis of the coded morphological traits employed grouped C. frutescens and C. chinense on a clade and C. annuum on a separate clade. However, the analysis of seed protein profiles of the studied species revealed that C. annuum and C. frutescens were genetically closed while C. chinense was distantly related to the two species. All the species studied were annuals and facultatively self-fertilized. The species studied possessed many similar characters showing the affinity that exists among them and in addition, they shared some generic bands. The tetracytic and anosocytic stomata were predominant in all Capsicum species studied. The presence of starch granules in the leaf parenchyma cells and the paracytic stomata on the abaxial leaf surface of C. chinense as well as the jugshaped midrib of C. chinense distinguished this species from the other two species. More so, the absence of trichomes and islets in C. annuum made it stand out among the three species. However, the chromosome numbers seem not to be useful taxonomically in this study, as all the species studied possessed the same number of chromosomes though the analysis of the seed protein profile revealed that the species studied were distinct. Therefore, the morphological, anatomical and electrophoretic studies have been proven to be useful in the present study and the study concluded that all the species studied were distinct species from a common origin.