Association of putative viral RNA sequences to flower colour variegation in Japanese primrose (Primula sieboldii E. Morren)

Flower colour variegation is characteristic symptom of viral infections in ornamentals such in the case of camellia, tulip, petunia, and daffodil. This is also seen in different cultivars of Japanese primrose like ‘Shichikenjin’, ‘Sotorihime’ and ‘Isaribi’, signifying a possible viral origin. Putative viral RNA sequences were first identified in the Primula sieboldii databases. Total RNA was then isolated and reverse transcriptase polymerase chain reaction was done using virus-specific primers to identify the association between the presence of putative viral RNA sequences and flower colour variegation. Five putative viral RNA homologous sequence groups were identified, with a possible virus identity of Cycas necrotic stunt virus, Lettuce big-vein associated virus and Rosa multiflora cryptic virus. Results showed that instances of amplifications were seen in both variegated and non-variegated within and across cultivars denoting the presence of putative viral RNA and a possible viral morbidity in the amplified cultivars. Instances wherein amplification of non-variegated flowers, while no amplification of variegated flowers within the same cultivar were also observed. Variegated plants of cultivars which had variegated and non-variegated flowers had a weak correlation. Thus, no definite association could be deduced from the presence of putative viral RNA and flower colour variegation. It is also recommended that flower tissue should be used for gene expression analysis to avoid error in differential gene expression.