Regeneration of pinwheel phenotype and evaluation of anthocyanin in African violet (Saintpaulia ionantha Wendl.) periclinal chimera

The mutation in the meristem layers creates different genetic backgrounds (chimera) in the plant tissue. The mutation in L1 layer of shoot apical meristem generates a periclinal chimera. UF3GT is an effective enzyme in floral coloration, inducing anthocyanin accumulation in petals. This study investigates direct and indirect regeneration systems and different explants to propagate two cultivars of periclinal chimera (Saintpaulia ionantha), namely Taro taraneh and Aghaz, using in vitro culture. The evaluation of UF3GT gene expression pattern by Real-Time PCR revealed the role of anthocyanin accumulation in the petal coloration of chimera plants. Results pertaining to both cultivars showed that inflorescence and leaf explant had the highest and lowest percentage of pinwheel phenotype, respectively. In addition, mutant characteristics were faded in the leaf regeneration of periclinal chimera. Furthermore, the highest percentage of periclinal chimera was generated in direct regeneration. Gene expression analysis revealed that UF3GT was expressed in the colorful part of chimera petal, while UF3GT expression was significantly reduced in the muted part. HPLC chromatogram also detected that cyanidin and delphinidin components were not present in the white part of either cultivar. The anthocyanin biosynthesis pathway appears to be blocked and anthocyanin accumulation does not occur in the petals. Inflorescence is likely to induce a pinwheel pattern in regenerated plants, probably owing to its lateral bud. It seems that different meristem layers are associated with the formation of epidermis and induce pinwheel phenotype.