Mutual symbiotic fungus Piriformospora indica promotes plant growth by inducing auxin de novo biosynthesis and triggering auxin signal response pathway

摘要

Piriformospora indica shows a high potency in enhancing plant host growth, disease resistance and stress tolerance after root colonization with the host. In the mutual symbiosis of P. indica with Chinese cabbage (Brassica campestris subsp. Chinensis), a transient increase of auxin level and signal transduction pathway was observed, besides the strong development of root hairs and lateral roots. The phenotype observed and auxin de novo biosynthesis are different from the observations in other plants. The observation prompt us to further investigate the molecular basis of the transcriptional mechanism activated by P. indica-colonization. Based on the analysis of the double subtracted expression sequence tag library (EST library), the dominantly active genes in EST data bank are helpful to validate the mechanism of growth promotion. Many genes such as auxin biosynthesis and signaling, cell membrane transporters, cell wall expansion, and ROS redox homeostasis were activated after P. indica-colonized process. The results give a hint that the response and mechanism triggered by P. indica in the colonized plant host might be different and plant species-dependent.