Pleurotus ostreatus bHLH transcription factors regulate plant growth and development when expressed in arabidopsis

Abstract

Fungi interact with plants in different ways in nature; however, it remains largely unclear if fungus gene may affect plant growth and development. Basic helix-loop-helix (bHLH) transcription factors are found in almost all organisms including plants and fungi. By using bioinformatics analysis, we found that there are 12 genes in Pleurotus ostreatus which encode bHLH transcription factors, namely P. ostreatus basic helix-loop-helix1 through 12 (PobHLH1-PobHLH12). By taking PobHLH1, 2, 5 and 8 as examples, we examined whether PobHLHs may regulate gene expression and plant growth and development when expressed in Arabidopsis. We found that all the four PobHLHs examined were localized in the nucleus; however, PobHLH2, 5 and 8 activated whereas PobHLH1 repressed reporter gene expression in transfected protoplasts. On the other hand, ectopic expression of PobHLH5 or 8 inhibited plant growth and development, whereas transgenic plants expressing PobHLH1 and PobHLH2 were largely morphologically similar to the wild-type plants.