Cloning and Expression Features of Cryptochrome Genes , ShCRY 1 and ShCRY 2 , from Chia ( Salvia hispanica )

Chia (Salvia hispanica L.) has outstanding nutritional and health-promoting values. After its rediscovery, this crop is being expanded worldwide, but the short-day flowering habit is a crucial limiting factor. Cryptochomes (CRYs) are blue-light receptors regulating flowering time through photoperiod-pathway. Full-length cDNAs of two chia CRY genes, ShCRY1 and ShCRY2, were cloned and investigated, both of which had alternative transcription initiation and poly-A tailing sites. They have DNAphotolyase and FAD-binding 7 domains, and ShCRY1 also has a Cryptochrome_C domain. Evolutionary study showed that plant-type CRY originated in green algae, accompanying the emergence of green plants. Since Selaginella moellendorffii, CRY in all vascular plants has undergone diverse duplications; especially the event generating higher plant CRY1 and CRY2 accompanied the origin of seed plants. ShCRY1 had significant expression in large leaves, buds and flowers, with the highest in small buds. ShCRY2 had a higher expression in middle buds, big buds and flowers, but extremely lower in small buds. In sunny days, both ShCRY1 and ShCRY2 showed higher expression during night than in the daytime, with a sharp peak at midnight. In cloudy and rainy days, their expression was low, with a small peak at noon, but no peak at midnight. Expression of ShCRY1 and ShCRY2 was upregulated by exogenous KT, BR, GA3 and IAA in long-days, while downregulated in short-days, with GA3 being the strongest phytohormone and ShCRY2, being more sensitive than ShCRY1. After treatments with diverse abiotic stresses, the expression of ShCRY1 and ShCRY2 fluctuated, while the trends of inhibition by high temperature and ABA and mild promotion by MeJA were still distinct. This is the first report of CRYs from the order Lamiales, which will promote the dissection of flowering mechanism of chia and other short-day plants, and enrich the evolution and expression knowledge of plant CRYs. © 2018 Friends Science Publishers