Abstract
Dioscorin is one of the major soluble proteins in yam tubers. Unlike other well-known plant storage proteins, such as patatin and sporamin, dioscorin is argued for its function as storage proteins, and the molecular mechanisms underlying its expressional complexity are little understood. In this study, we isolated five dioscorin genes from Dioscorea alata L., comprising three class A (Da-dio1, -3 and -4) and two class B (Da-dio2 and -5) isoforms. Expressions of all dioscorin genes gradually decreased in mother tubers during yam sprouting and regrowth. On the other hand, all dioscorin genes accumulated transcripts progressively with tuber development in new tubers, with Da-dio5 being the most prominent isoform. In yam leaves, the expressions of Da-dio5 were up-regulated by the treatments of five phytohormones (gibberellic acid, salicylic acid, indole-3-acetic acid, abscisic acid, and ethylene), and three abiotic stresses (high-temperature, low-temperature and drought). To further elucidate the regulatory mechanisms of Da-dio5 expressions, transgenic Arabidopsis plants harboring the Da-dio5 promoter-β-glucuronidase (GUS) fusion were generated. GUS staining showed that expressions of the Da-dio5 promoter were detected mainly in the shoot apical meristem (SAM) and hypocotyls, and enhanced by the treatments of the five hormones, and the three abiotic stresses mentioned above. These results suggest diverse roles of Da-dio5 in yam sprouting, regrowth, and tuberization, as well as in response to enviromental cues.
Highlights
Yams (Dioscorea spp.) are members of the monocotyledonous family Dioscoreaceae
Multiple sequence alignments were performed upon the five D. alata dioscorin (Da-dio) proteins identified here, a dioscorin homolog from Dioscorea japonica and three carbonic anhydrases (CAs) from human (P00915), mouse (P13634) and Arabidopsis (CAB79100), respectively
Tuber growth is reported to be accompanied by protein depletion along with sugar mobilization, which is controlled by the redox status of the tubers [27]
Summary
Yams (Dioscorea spp.) are members of the monocotyledonous family Dioscoreaceae. More than 600 yam species have been cultivated worldwide [1], consumed as an important source of food in some African and Asian countries due to the high contents of carbohydrate and nutritionally relevant proteins (1–3%) in fresh tubers [2,3]. Dioscorin has been argued for its function as a storage protein despite its high abundance in yam tubers. The well-known tuber storage proteins, such as sporamin from sweet potato and patatin from potato, contribute to pest and pathogen resistance, as well as resistance to abiotic stresses [1,17,19,20]. These findings suggest that the so-called storage proteins including dioscorin may have dual roles related to storage and defense in plants
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
