Acquisition, identification and analysis of an interspecific Capsicum hybrid (C. annuum x C. chinense)

Using an embryo rescue technique, we obtained an F-1 plantlet whose female parent was a purple chilli pepper (Capsicum annuum 7033) and whose male parent was a green chilli pepper (C. chinense 7020). We verified the origin of this interspecific hybrid using a peroxidase isozyme assay and random amplified polymorphic DNA (RAPD) markers. Most of the morphological features of the F-1 plant, particularly the purple colour of its foliage, flowers and immature fruit, were intermediate between those of its parents. Cytological analysis indicated that the meiotic chromosomes of the pollen mother cells of the F-1 plant exhibited abnormal behaviour, resulting in a marked reduction in the proportion of fertile pollen compared to both its parents. Sequence analysis of the internal transcribed spacer of nuclear ribosomal DNA demonstrated that, compared to the parental sequences, the F-1 hybrid had 186 polymorphic sites, 139 of which (74.7%) were inherited from the male parent, and 23 (12.4%) were inherited from the female parent, and 24 (12.9%) were transversions or base pair mutations. Therefore, our morphological and cytological observations, as well as isozyme and molecular marker analyses confirmed that the F-1 plant was a genuine interspecific hybrid that had inherited more genetic information from its male parent than from its female parent. This work will help locate purple colour-related genes and the breeding of pepper cultivars containing higher concentrations of anthocyanin and capsaicin.