Mphy gene reveals the involvement of light source in the regulation of pigment metabolism in Monascus ruber

The growth, development and pigment metabolism of Monascus are regulated by light. However, the function of the photoreceptor gene in the Monascus genome has not yet been clearly verified. In this paper, the gene sequence Mphy, which is homologous to plant phytochrome, was firstly found from Monascus ruber C100 by comparing it with the genome. Then, taking M. ruber C100 as the main research object, by knocking out and overexpressing the Mphy gene, the involvement of Mphy in the regulation of light on the growth and develop-ment of Monascus and the metabolism of Monascus pigments (MPs) were preliminarily explored. Compared with the original strain C100, the Mphy knockout strain (Delta Mphy) and the overexpression strain (OE-Mphy) grew slowly and produced low spores. At the same time, under different light conditions, red light can promote the growth and sporulation of Monascus, while blue light can inhibit it. MPs are positively regulated by the Mphy gene, that is, the deletion of the Mphy gene reduces the production of MPs, while the overexpression of the gene increases the accumulation of the pigment, especially under red light conditions. These results indicate that the homologous genes of phytochromes are involved in the process of light-regulated growth, development and pigment metabolism in Monascus. Based on the above results, we found that under red light conditions, Mphy controls the process of pigment metabolism by affecting key enzymes in TCA metabolism and key signaling pathways such as the MAPK signaling pathway.