Solanum tuberosum (CYCLING DOF FACTOR) CDF1.2 allele: A candidate gene for developing earliness in potato

Circadian clock regulated CDF (CYCLING DOF FACTORs) are a cluster of transcriptional repressors, that accentuates a major quantitative trait locus (QTL) for earliness in potato. Earliness in the plant is a desirable agronomic trait for higher productivity and also enable it to withstand various biotic and abiotic stresses. Since potato is a temperate crop, its tropicalization in the Indian subcontinent is a major agricultural challenge. StCDF1 induce a photoperiod-dependent tuberization pathway by interacting with other molecular regulators such as CONSTANS (StCO1/2) and StSP6A. The present study was conducted to elucidate the allelic variation, expression, role in flowering and tuberization of StCDF1 in contrasting tuberization behaviour of diverse Indian potato cultivars, Kufri Surya (KS) and Kufri Chandramukhi (KCM). Our results confirmed two allelic forms of StCDF1 viz. CDF1.2 and CDF1.3. Their expression profile suggests a higher upregulation of both CDF1.2 and CDF1.3 expression at dawn (6:00 am) than noon (12:00 pm). Virus-Induced Gene Silencing was used to validate the role of these alleles with respect to earliness and tuberization in KS. Real-time confirmed the upregulation of StCO and StSP5G and downregulation of StSP6A in VIGS plants. Phenotypic observations suggested delayed tuberization and a low tuber number in VIGS plants. This present study confirms the allelic variation, the importance and functionality of StCDF1.2 in conferring earliness in tetraploid potato cultivars.