Origin of the Capsicum CMS cytoplasm revealed by cytoplasmic DNA derived marker analysis

Cytoplasmic male sterility (CMS) is the maternally inherited inability to produce functional pollens. Although the CMS cytoplasm from the pepper Capsicum annuum (PI164835) has been widely used to produce F1 hybrid seeds, the origin of this cytoplasm has not been studied at the DNA sequence level. Because the plastid genome is co-transmitted with and is highly stable compared to mitochondrial genome, we used plastid barcode sequences to deduce the CMS cytoplasm origin. Two intergenic plastid sequences, trnH–psbA and rpl16–rpl18, were used to analyze pepper germplasm cytoplasm types from six different Capsicum species. Cytoplasm types could be divided into six and four different types for the trnH–psbA and rpl16–rpl18 intergenic sequences, respectively. Sequences of these two regions in CMS pepper lines were identical to those of pepper lines belonging to a particular C. annuum clade. This identity was confirmed by investigation using a larger germplasm number and markers derived from mitochondrial sequences. Our results suggest that the CMS cytoplasm of C. annuum PI164835 may have originated from a female plant belonging to the C. annuum clade.

► Two plastid sequences were analyzed for pepper CMS lines and various lines in Capsicum species.
► Haplotypes of plastid sequences in CMS pepper were identical to haplotypes for a particular C. annuum clade.
► CMS cytoplasm of C.annuum may have originated from a female plant belonging to a C. annuum clade.