Sweet potato cv. Xushu 18 was used in this study. Plants were grown on test field under natural conditions in May of 2009 at Sichuan University. For 2-DE analysis, we harvested the unexpanded young leaves and the fully expanded mature leaves ( Supplementary Fig. S1) at midday and frozen immediately in liquid nitrogen. For cloning of the two RCA isoform genes, the fully expanded leaves of sweet potato were collected. To investigate whether mRNA's expressed pattern of Ib-RCA in leaf tissue is regulated by light, we harvested mature leaves every 2 h throughout a 24 h period. In order to investigate the temperature responses of Ib-RCA genes, sweet potato growing in field was transplanted to climate box (25°C under a 14/10 h light/dark photoperiod and 200 lEm -2 s -1 ). After continuous light (25°C, 200 lEm -2 s -1 ) treatment for 2 days, sweet potato was then treated at different temperatures (20, 25, 30, 35°C and 200 lEm -2 s -1 ) for 24 h. We sampled and frozen immediately in liquid nitrogen, then stored at -80°C until use. Sequences **data** from this article have been deposited at GenBank (http://www.ncbi. nlm.nih.gov) under accession numbers JQ923423-JQ9234231.