Evaluation of abiotic stress tolerance and physiological characteristics of potato (Solanum tuberosum L. cv. Kennebec) that heterologously expresses the rice Osmyb4 gene

Abstract

MYB transcription factors are involved in diverse biochemical and physiological processes, including hormone signaling, defense, and stress responses. In the present study, we developed a transgenic potato (Solanum tuberosum L. cv. Kennebec) expressing the rice Osmyb4 gene, which encodes the transcription factor MYB4. The transgene was under the control of either the constitutive CaMV35S promoter or the stress-induced Arabidopsis COR15a promoter. The potential involvement of MYB4 in certain physiological processes and the abiotic stress response in the potato was evaluated. The transgenic plants did not exhibit growth retardation, and they showed no significant difference (P < 0.05) in tuber yield from that of non-transgenic wild-type plants. Although the chlorophyll a and b as well as the anthocyanin contents of the six transgenic lines were similar to those of the wild type, the transgenic line S2 presented a significantly higher carotenoid content. The total sugar contents of the lines S2 and M48 were significantly higher than that of the wild-type plants. S2 and M48 were significantly more tolerant of salinity than the wild type, according to measured growth parameters. Transgenic plants grown under a high concentration of boric acid (3 mM) exhibited greater survival rates than non-transgenic control plants. On the other hand, the transgenic plants did not show an improvement in freezing tolerance. Overall, our results indicated that MYB4 may affect diverse processes such as carotenoid biosynthesis, sugar metabolism, and salinity tolerance in potato, and that it may be an upstream regulatory element of these processes.