Factors influencing successful establishment of exotic Pinus radiata seedlings with co-introduced Lactarius deliciosus or local ectomycorrhizal fungal communities

An introduction of exotic or non-native trees may fail due to a lack of suitable fungal partners. We planted exotic Pinus radiata in Xifeng, Guizhou Southwest China. Strategies to introduce P. radiata seedlings either colonized with an ectomycorrhizal fungus (EcMF), Lactarius deliciosus, or expect them to form familiar/new associations with local EcMF in a new habitat were studied to know how P. radiata could be successfully established over a period of 2.5 years. Plant height and needle nutrient acquisition, the persistence of the co-introduced L. deliciosus, and fungal community composition in rhizosphere soil and root tips were analyzed. In addition, a greenhouse bioassay experiment of local soil to assess the differences in the EcMF community between exotic and native pine seedlings was also conducted. The current results demonstrated that P. radiata could establish in the Xifeng plantation with or without co-introduced L. deliciosus. The co-introduced L. deliciosus might be naturalized with P. radiata in the new area since it has been fruited for 2 years with high relative abundance in mycorrhizosphere soil. L. deliciosus pre-colonization significantly altered the mycorrhizosphere fungal composition and it had a positive correlation with nitrogen acquisition of P. radiata. Host identity had no effect on fungal composition since exotic P. radiata and native P. massoniana recruited similar local fungal communities in early establishment or in plantation. The cosmopolitan species Suillus placidus, with high relative abundance, formed a familiar association with P. radiata. The greenhouse bioassay experiment further showed that Suillus sp. contributed relatively higher total extracellular enzymes by forming ectomycorrhizas with P. radiata and the same type of ectomycorrhiza of P. radiata and P. massoniana showed different enzymatic functions. Our study indicated that exotic P. radiata could be a suitable tree capable to get established successfully in the Xifeng plantation either by interaction with the co-introduced L. deliciosus or with a local EcMF, but we should be cautious about large-scale planting of P. radiata. L. deliciosus persisted in plantation and more attention should be paid to local EcMF community changes induced by the introduced L. deliciosus.This work was supported by the Fund of Yunnan Key Laboratory for Fungal Diversity and Green Development (No. E03A311261-6), the National Sciences Foundation of China (No. 31901204), and the Yunnan Key Project of Science and Technology (No. 202102AE090034)

Traceability of Marketable Japanese Shoro in New Zealand: Using Multiplex PCR To Exploit Phylogeographic Variation among Taxa in the Rhizopogon Subgenus Roseoli ▿ †

Rhizopogon roseolus Corda (synonym Rhizopogon rubescens Tul.), an economically important edible mushroom associated with the Pinaceae (mostly Pinus sp.), has a global distribution resulting from the introduction of exotic trees into the Southern Hemisphere for plantation forestry. However, the marketability of R. roseolus varies with the place of origin. R. roseolus strains cultivated in New Zealand from local carpophores for the Japanese market are morphologically and biologically distinct from those produced in Japan and are consequently considered less valuable. In this study, the ITS1-5.8S-ITS2 rRNA (internal transcribed spacer [ITS]) region was used to examine the phylogenetic relationships of R. roseolus and other closely related fungi belonging to Rhizopogon subgenus Roseoli to determine the genetic basis for phenotypic differences among R. roseolus isolates from different geographic regions. Phylogenetic comparison revealed phylogeographic variation within Rhizopogon subgenus Roseoli. Collections from the United States and Europe grouped into four distinct clades. Rhizopogon roseolus isolates found in New Zealand were closely related to those from the United States, likely due to introduction of Pinus radiata from its native California in the United States. In contrast, Japanese R. roseolus isolates clustered closely with European collections. Phylogenetic differences between Japanese and New Zealand R. roseolus isolates may explain the morphological and biological properties attributed to these geographical variants. The ITS region was subsequently used to design a multiplex PCR for the simultaneous identification of Japanese and New Zealand R. roseolus isolates to track the establishment of ectomycorrhiza on P. radiata seedlings inoculated with commercially valuable R. roseolus. This diagnostic demonstrated the first fruiting of Japanese shoro cultivated on P. radiata in the Southern Hemisphere

Mycorrhizal syntheses between Lactarius spp. section Deliciosi and Pinus spp. and effects of grazing insects in Yunnan, China

Ectomycorrhizal fungi (EMF) in Lactarius sect. Deliciosi produce valuable edible mushrooms. Market supplies are harvested from natural populations. Sustainable cultivation could increase commercial crop production. The first step in EMF cultivation is the production of host seedlings well-colonised by the target species. The aim of this study was to compare the efficiency of vegetative versus spore inoculum for controlled mycorrhizal synthesis between Lactarius and Pinus species native to China. Inoculated seedlings were incubated in a glasshouse for up to 14 months. Mycorrhizae were synthesised, using vegetative inoculum, for 13 distinct combinations of five Pinus and four Lactarius species, 12 of these unprecedented. Spore inoculation was not successful. The successful mycorrhization presented here provides a foundation for establishing mushroom orchards, with L. deliciosus x P. yunnanensis or P. radiata, L. hatsudake x P. yunnanensis or P. tabuliformis, and L. vividus x P. massoniana or P. radiata appearing promising symbionts for cultivation. From 5 months following inoculation, mycorrhizal seedlings underwent extensive insect grazing. Adult forms of Bradysia impatiens were the most frequent insects caught on sticky traps, while their larvae were observed foraging through roots. The control of insects in the nursery will be critical to large-scale production of mycorrhizal seedlings.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Genetic relationship of Tricholoma matsutake and T. nauseosum from the Northern Hemisphere based on analyses of ribosomal DNA spacer regions

International audienceThe genetic relationship among Tricholoma matsutake and T. nauseosum strains collected from various parts of the Northern Hemisphere was investigated using sequence analysis of the rDNA ITS region and PCR-RFLP analysis of the rDNA IGS-1 region. ITS sequence similarity between T. matsutake and T. nauseosum ranged between 98.1% and 100%. The strains of T. matsutake from coniferous forests and those from broad-leaved forests showed more than 99.8% similarity in their ITS sequences. Three distinct RFLP types were detected when IGS-1 regions were digested with Cfr13I. RFLP patterns showed no variability among the strains of T. nauseosum and those of T. matsutake from broad-leaved forests. This pattern corresponded to the dominant RFLP type in the Japanese population of T. matsutake. Thus, strains belonging to this RFLP type are widely distributed throughout East Asia and Europe and associated with many tree species of Pinaceae and Fagaceae. The result suggests that T. matsutake in coniferous and broad-leaved forests and T. nauseosum should be treated as the same species genetically

Edible mycorrhizal fungi of the world : what is their role in forest sustainability, food security, biocultural conservation and climate change?

Societal Impact Statement Edible mycorrhizal fungi (EMF) have been consumed since ancestral times by humans either as food, medicine or for ceremonial use. Nowadays, they are a non-timber forest product and a diverse genetic resource with great ecological, sociocultural, economic, medicinal and biotechnological relevance around the world. Therefore, they have a paramount role to play in meeting the United Nations global sustainable development goals 2030. EMF may promote forest sustainability, biodiversity conservation, mitigation of greenhouse gas emissions through the maintenance of forest masses, human nutrition and health, economic development, conservation of biocultural heritages, women empowerment and hunger mitigation. We provide a worldwide review of the knowledge, biodiversity, novel approaches, future challenges and perspectives in the post-COVID era of this important genetic resource whose relevance has usually received marginal attention despite its strategic global significance. Ectomycorrhizal fungi play a key role in the structure and functioning of forest ecosystems. They have a paramount importance in nutrient cycling, plant protection against pathogens and abiotic stress, and establishment of underground networks that connect trees and other plants in nature, therefore being the wood wide web, the 'internet' of the forests. According to our literature review, globally 970 mycorrhizal fungal species (including both mushrooms and truffles) are edible, and they have enormous relevance either as a source of subsistence in low-income human groups around the world or as an important economic component whose international commerce is worth billions of American dollars annually. Since edible mycorrhizal fungi (EMF) are a non-timber forest product, their sustainable use and management is crucial in order to maintain forest stands and to provide well-being to the human communities surrounding the forested areas where they grow. In different parts of the world, different cultures have developed a traditional knowledge of EMF over millennia. Their knowledge might play an important role in food supply and food security in the future, hence contributing towards the "zero hunger" global goal. The biotechnological development of EMF has also been crucial in the establishment of plantations, or successful reforestation and ecosystem restoration, which contribute to climate change mitigation by reducing greenhouse gas emissions. Here, a worldwide review of how EMF might contribute to forest sustainability, food supply, biocultural conservation, and hunger and climate change mitigation is addressed by analysing the similarities, contrasts and challenges in all five continents

Comparative genomics reveals a dynamic genome evolution in the ectomycorrhizal milk‐cap (<i>Lactarius</i>) mushrooms

International audienceEctomycorrhizal fungi play a key role in forests by establishing mutualistic symbioses with woody plants. Genome analyses have identified conserved symbiosis-related traits among ectomycorrhizal fungal species, but the molecular mechanisms underlying host specificity remain poorly known. We sequenced and compared the genomes of seven species of milk-cap fungi (Lactarius, Russulales) with contrasting host specificity. We also compared these genomes with those of symbiotic and saprotrophic Russulales species, aiming to identify genes involved in their ecology and host specificity. The size of Lactarius genomes is significantly larger than other Russulales species, owing to a massive accumulation of transposable elements and duplication of dispensable genes. As expected, their repertoire of genes coding for plant cell wall-degrading enzymes is restricted, but they retained a substantial set of genes involved in microbial cell wall degradation. Notably, Lactarius species showed a striking expansion of genes encoding proteases, such as secreted ectomycorrhiza-induced sedolisins. A high copy number of genes coding for small secreted LysM proteins and Lactarius-specific lectins were detected, which may be linked to host specificity. This study revealed a large diversity in the genome landscapes and gene repertoires within Russulaceae. The known host specificity of Lactarius symbionts may be related to mycorrhiza-induced species-specific genes, including secreted sedolisins