INSIGHTS INTO LEAF ANTHOCYANIN REGULATION FOR POTATO TOLERANCE TO ENVIRONMENTAL STRESSES

Anthocyanins are important pigments for plant physiological and reproductive processes. The presence of high anthocyanin content in vegetative tissues aids the plant in responding to environmental stresses. Potato plants have anthocyanins in reproductive organs, tubers and also in leaves. The molecular knowledge on anthocyanin regulation in potato has been limited to the identification of a MYB transcription factor gene (StAN1). In this study we aimed to investigate the mechanisms underlying anthocyanin production in potato, focusing on the role of vegetative tissues for plant protection. Our research elucidated the MYB/bHLH complex involved in anthocyanin regulation through the study of two StAN1 co-factor genes, StJAF13 and StbHLH1. We found that the two bHLHs physically interact with StAN1 and that the complex enhances pigments production in transgenic tobacco. Interestingly, StJAF13 was the gene whose expression in leaves correlated more consistently with that of the anthocyanin structural genes. Therefore, StJAF13 can be considered as the mainly StAN1 co-factor related to the specific production in this tissue. Further orthology analysis with the cold tolerant potato species Solanum commersonii revealed a particular evolutionary history of StAN1 and suggested new aspects related to the role of anthocyanin genes in cold stress response.