Indole-3-acetic acid (IAA) stimulates rapid and long-term responses in plants and has been identified in plant-associated bacteria, fungi, and yeasts. The role of microbial IAA in species interaction networks has recently received increasing attention. In this study, we used Ustilago esculenta JYC070, a yeast strain with high IAA-producing ability, and closely related species to investigate the IAA-producing ability, and other yeast species to investigate the roles of IAA in fungal growth. The effects of exogenous IAA on yeast growth were determined to uncover the biological role of IAA. IAA was observed to exert stimulatory and inhibitory effects on yeast growth, and such effects were strain dependent. Furthermore, we observed that the cocultivation of Nicotiana benthamiana plants with U. esculenta JYC070 enhanced plant growth, indicating a potential yeastplant interaction mediated by IAA. The region of root apical meristem was enlarged in N. benthamiana plants cocultivated with the yeast. Overall, these results suggest that yeast-produced IAA is not only involved in the competition among yeasts but also promotes plant growth and development. This leads to the hypothesis that natural selection might have favored the evolution of IAA as a signaling molecule in the interactions among these organisms.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Plant Science