Genetic variability within a Capsicum annuum collection

Introduction Pepper belongs to the genus Capsicum (Solanaceae), which includes about 25 wild and five domesticated species. Besides being one of the most commonly used spices, condiments and vegetables, peppers have several versatile and innovative food and non-food uses, being natural source of capsaicinoids, alkaloids, antioxidants, vitamins, and carotenoids to use in therapeutic and wellness applications [1]. Among Capsicum spp., C. annuum pungent and non-pungent (sweet) fruits are commercially important because cultivated worldwide. They originated in the Americas and spread rapidly through the globe after the voyage of Columbus. Routine species and cultivar identification of pepper is essentially based on phenotypic traits, which can be variable indicators of the specific pepper genotype since affected by environmental conditions [1,2]. Level of genomic diversity among and within species of the genus Capsicum can be evaluated by means of DNA-based molecular markers, a versatile and effective diagnostic tool. This study investigated the genetic diversity in a population of C. annuum using Random Amplified Polymorphic DNA (RAPD) markers, which are regions of genome amplified by polymerase chain reaction (PCR) using single primer of arbitrary sequence. Method The 32 C. annuum individuals here analyzed represent a newly assembled hot pepper collection consisting of 14 accessions. Leaves for molecular analysis were harvested from one to three individuals per each accession. Genomic DNA extraction and RAPD-PCR followed previous protocols with minor modifications [1,2]. The three primers AE19: GACAGTCCCT, AG14: CTCTCGGCGA, and AN19: ACCACGCCTT were selected. Amplicons were detected after gel electrophoresis and reproducible bands were coded in a binary format by scoring for the presence or absence. A similarity matrix based on Nei and Li's coefficient was calculated for all genotypes and used to construct a tree plot (dendrogram) based on UPGMA algorithm. Results and Discussion RAPD analysis identified 31 reliable alleles, with a mean of 10.33 alleles per primer on C. annuum collection. Twenty-eight loci were polymorphic (90%) and their variation allowed to properly identify the 14 C. annuum accessions and to assess their genetic relationships. Cluster analysis, according to their genetic polymorphism, confirmed the morphological classification with sub-clustering that reflect the differences at genetic level of the individuals of the same variety. These results were in agreement with previous studies1,2 and confirmed the complex nature of relationships within the species level. In this regard, further studies are ongoing on the species C. chinense, C. baccatum, and C. frutescens. Conclusion Based on these outcomes, RAPD-based method could be used as molecular tool for distinguishing Capsicum species and varieties. Moreover, these findings strengthen the idea to use molecular markers to appropriately manage hot pepper collections so to perform innovative breeding programs. Bibliographic References 1. De Masi L, Siviero P, Castaldo D, Cautela D, Esposito C, Laratta B (2007). Mol Nutr Food Res 51, 8: 1053-1062. 2. Laratta B, De Masi L, Sarli G, Pignone D (2013). In Proceedings of the XV EUCARPIA Meeting, Eds S. Lanteri and G. L. Rotino, pp. 233-240. ISBN: 978-88-97239-16-1.