Structural homologs of CONSTANS and LEAFY in potato and its wild relatives

The putative homologs of CONSTANS and FLORICAULA/LEAFY are primary candidate genes for the control of flowering and tuberization in potato. CONSTANS homologs were cloned from potato (Solanum tuberosum subsp. tuberosum) 'Bastoneza' and 'Early Rose' (GenBank accession numbers DQ472734 and DQ499754) and S. demissum (DQ499755). Their amino acid sequences greatly resembled CONSTANS from S. tuberosum subsp. andigenum (S. Prat, pers. commun.) and CONSTANS 1 and CONSTANS 3 from S. lycopersicum (AAS67377 and AAS67379). Long-day tuberosum plants notably differed from short-day andigenum and demissum in the variable middle region of the CONSTANS protein, especially by the length of polyasparagine and polyglutamine motifs. Partial homologs of the FLORICAULA/LEAFY protein from potato (ABB69053, ABB72204, ABB76758-ABB76760) and demissum accessions (ABB69052, ABB72202, and ABB72203) shared 94% identity with tomato FALSIFLORA (AAF66101). FLORICAULA/LEAFY intron 2 (FLint2) revealed extensive inter- and intraspecific polymorphism. The search for putative cis-regulatory elements in FLint2 alleles returned SQUAMOSA/APETALA1 footprints whose distribution seems to differ in andigenum, demissum and tuberosum accessions.