Recently, Team of Dr. Qingping Wu, academician of the Chinese Academy of Engineering and honorary director of the Institute of Microbiology, Guangdong Academy of Sciences, discovered a potential key factor restricting the artificial cultivation of russula. Related research was published in Genes with the title of "Whole genome sequencing of an edible and medicinal mushroom, Russula griseocarnosa, and its association with mycorrhizal characteristics".
Russula spp are kinds of wild edible mushroom with distinctive regional characteristics. Among them, Russula griseocarnosa is a famous ectomycorrhizal edible mushroom, which is mainly distributed in southern China. Because it is rich in vitamins, amino acids and minerals that are beneficial to the human body, it is praised as a longevity food by the locals. As the mycelium of Russula is difficult to grow on artificial culture medium, there is no accurate method for artificially cultivating the fruit body. The edible red mushrooms in the south are commonly known as " Dahongjun (big red mushroom)". They contain three phylogenetic branches that are mutually monophyletic. The Russula griseocarnosa is only one of the branches, and the species are very similar. Therefore, the Russula griseocarnosa and other Russula spp are often confused.
The researchers investigated and identified the resources of Russula in South China, obtained the accurate fruit bodies of Russula griseocarnosa, and sequenced the whole genome using second- and third-generation sequencing technologies based on the extracted high-quality genomic DNA. High-throughput sequencing data was de novo assembled and GeneMark-ES, BLAST, CAZy and other databases were used for functional gene annotation. A phylogenetic tree was constructed based on the single-copy genes of different nutritional habits fungi. Comparative genomics analysis was conducted between Russula griseocarnosa and other four representative species.
The results of this study showed that the distribution of carbohydrate hydrolase of Russula griseocarnosa is similar to that of other mycorrhizal fungi such as Tricholoma matsutake and Suillus luteus, but the number and species are less than that of saprophytes, especially carbohydrate binding modules (CBMs) and Carbohydrate esterase (CEs), this may be the potential reason why it is difficult to use artificial carbon source medium to complete growth. No small secretory proteins (MiSSPs) related to mycorrhizal induction were found in Russula griseocarnosa, which indicates that there may be some special effect proteins that interact with host plants in Russula griseocarnosa.
"The conventional research method for the determination of high-quality genomes of macrofungal is to use its monocytic hyphae. Species of Russula are the symbiotic fungus. So far, no hyphae have been isolated.
it is very difficult to finish the high-quality genome directly by the fresh fruit bodies", Hu Huiping, a senior engineer at the Institute of Microbiology, Guangdong Academy of Sciences, told the China Science Daily.
The results of this study provide genetic data support for the evolution of the nutritional ecology of macrofungal, especially mycorrhizal fungi, and lay the foundation for the next step of screening the available nutrient sources of Russula griseocarnosa.