Inter simple sequence repeat analysis of genetic diversity of five cultivated pepper species

Abstract

This paper studied the genetic diversity of five cultivated pepper species using inter simple sequence repeat (ISSR) analysis. The amplicons of 13 out of 15 designed primers were stable polymorphic and therefore were used as genetic biomarkers. 135 total clear bands were obtained, of which 102 were polymorphic bands with an average polymorphism rate of 75%. The cultivated species Capsicum annuum L. had less specific genotype bands compared with two wildtype species; its Nei's gene diversity index, Shannon's diversity index and genetic differentiation index were 0.21, 0.33 and 0.8306, respectively. The genetic variations of these five species were mainly interspecifically rather than intraspecifically. Cluster analysis showed that they belonged to different branches: C. annuum L., Capsicum chinense Jacquin. and Capsicum frutescens L. were in one cluster, whereas Capsicum baccatum L. and Capsicum pubescens Ruiz and Pavon were in another cluster. C. annuum L. had the least genetic polymorphism. Our results suggested that ISSR markers are valid tags in the studies on pepper genetic diversity and that cultivated species identification and gene exchange between cultivated and wild species should be strengthened in pepper breeding to improve heterosis.

Key words: Pepper, inter simple sequence repeat (ISSR), cultivated species, genetic diversity.