New CMS types in Plantago lanceolata and their relatedness

Abstract

 Mitochondrial variation in Plantago lanceolata was used to detect new CMS types. Directional reciprocal crosses were made between plants which differed in mtDNA restriction patterns. Differential segregation of male steriles in reciprocal crosses indicated that the parents differed in CMS type. MtDNA variation revealed nine RFLP patterns, which could be categorised according to the sex phenotype of the plants as MS1 (brown-anther type), MS2 (petaloid flower type) and MS3 (more yellow anthers than MS1). A single mtDNA pattern was found within MS1, six mtDNA patterns were found within the MS2 group, and two mtDNA patterns were found within hermaphrodites which segregated MS3 in the crosses. MS1 and MS2 are known to represent different CMS types, CMSI and CMSII. In reciprocal crosses between plants with different mtDNA patterns within the MS2 group, different ratios of male steriles segregated in the crosses, indicating that the parents differed in CMS type. Within the MS2 group two CMS types were found, designated CMSIIa and b. Finally, the sex phenotype H/MS3 turned out to be a different type. From previous studies it was known that the MS3 phenotype can also occur in CMSI and CMSII types, hence it is unclear whether MS3 is diagnostic for CMSIII. Since the data in this study cannot distinguish between the new type being a fully restored new CMS type or a ‘Normal’ cytoplasm, it was denoted as CMSIII. In total, four CMS types were found in the material studied. CtDNA variation was screened and three chloroplast haplotypes were identified. Two haplotypes were associated with CMSI plants, and one haplotype with the other CMS types. The ctDNA variation indicated that the CMSI type is widespread within the species, due to migration rather than to recurrent mutation. This may lead to the conclusion that only a limited number of CMS types are successful.