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Ectomycorrhizal 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.

Aims Arbuscular mycorrhizal fungi (AMF) can perform significant functions within sustainable agricultural ecosystems, including vineyards. Increased AMF diversity can be beneficial in promoting plant growth and increasing resilience to environmental changes. To effectively utilize AMF communities and their benefits in vineyard ecosystems, a better understanding of how management systems influence AMF community composition is needed. Moreover, it is unknown whether AMF communities in organically managed vineyards are distinct from those in conventionally managed vineyards. Methods and Results In this study, vineyards were surveyed across the Marlborough region, New Zealand to identify the AMF communities colonizing the roots of different rootstocks grafted with Sauvignon Blanc and Pinot Noir in both conventional and organic systems. The AMF communities were identified based on spores isolated from trap cultures established with the collected grapevine roots, and by next-generation sequencing technologies (Illumina MiSeq). The identified AMF species/genera belonged to Glomeraceae, Entrophosporaceae, and Diversisporaceae. The results revealed a significant difference in AMF community composition between rootstocks and in their interaction with management systems. Conclusions These outcomes indicated that vineyard management systems influence AMF recruitment by rootstocks and some rootstocks may therefore be more suited to organic systems due to the AMF communities they support. This could provide an increased benefit to organic systems by supporting higher biodiversity. [ABSTRACT FROM AUTHOR]

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 five 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 as promising symbionts for cultivation. Beginning 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. Key words: Lactarius section Deliciosi, Pinus, mycorrhizal synthesis, insect damage, Bradysia impatiens. Lactarius sect. Deliciosi regroupe des champignons ectomycorhiziens (CEM) qui produisent des champignons comestibles de valeur. Le marche est approvisionne par des champignons recoltes parmi les populations naturelles. L'exploitation durable pourrait accroitre la production commerciale. La premiere etape dans la culture des CEM est la production de semis de l'hote adequatement colonises par l'espece de champignon desiree. L'objectif de cette etude consistait a comparer l'efficacite de l'inoculum vegetatif versus les spores pour obtenir la synthese mycorhizienne controlee entre des especes de Lactarius et de Pinus indigenes en Chine. Les semis inocules ont ete incubes jusqu'a 14 mois en serre. Les mycorhizes ont ete synthetisees a l'aide d'inoculum vegetatif dans le cas de 13 combinaisons differentes impliquant cinq especes de Pinus et cinq especes de Lactarius, dont 12 etaient sans precedent. L'inoculation avec des spores n'a pas fonctionne. Les syntheses mycorhiziennes presentees ici fournissent les bases pour etablir des vergers de champignons avec L. deliciosus x P. yunnanensis ou P. radiata, L. hatsudake x P. yunnanensis ou P. tabuliformis et L. vividus x P. massoniana ou P. radiata qui semblent etre des symbiotes prometteurs pour la culture. A partir de cinq mois suivant l'inoculation, les semis mycorhizes ont subi un important broutage par les insectes. Les stades adultes de Bradysia impatiens sont les insectes les plus frequemment captures dans des pieges englues, tandis que leurs larves ont ete observees en train de s'alimenter au niveau des racines. La maitrise des insectes en pepiniere sera essentielle pour produire des semis mycorhizes a grande echelle. [Traduit par la Redaction] Mots-cles : Lactarius sect. Deliciosi, Pinus, synthese mycorhizienne, dommage cause par les insectes, Bradysia impatiens., Introduction Forest mushrooms that belong to Lactarius section Deliciosi (Fr.: Fr.) Redeuilh, Verbeken & Walleyn are harvested worldwide for food and income. These fungi live in mycorrhizal symbiosis with a [...]

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. [ABSTRACT FROM AUTHOR]

Truffle cultivation is successfully applied throughout the world for several truffles of European origin. However, just two Chinese black truffles (Tuber indicum and T. himalayense) have been cultivated with a favorable outcome so far. Tuber pseudohimalayense is a black truffle of significant economic relevance in China, but little is known about its mycorrhizal ecology and it is not cultivated in orchards yet. Here, we selected seven broad-leaved tree species (Quercus fabrei, Q. aliena, Castanea mollissima, Carya illinoinensis, Q. glauca, Castanopsis orthacantha, Betula costata), and one coniferous tree (Pinus armandii), and inoculated them with T. pseudohimalayense spore suspension using axenically germinated seedlings under greenhouse conditions. The obtained mycorrhizae, well-developed, were analyzed from the morpho-anatomical and molecular points of view, and their main characteristics described. Synthesized T. pseudohimalayense mycorrhizae showed similar characters on all tree species, with a typical interlocking pseudoparenchymatous mantle and Hartig net, swollen appearance, yellow-brownish color, and long hyaline emanating hyphae with right-angle ramifications. These features are similar to those reported for mycorrhizae formed by related black truffle species. The successful mycorrhizal synthesis of T. pseudohimalayense on multiple trees species indicates that it has potential for cultivation in China. [ABSTRACT FROM AUTHOR]

Phlebopus roseus is described as new based on collections from southwest China. Phylogenetic analyses of nuclear rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and portions of nuclear 28S rDNA (28S), translation elongation factor 1-alpha (tef1), and the largest and second largest subunits of RNA polymerase II (rpb1, rpb2) support P. roseus as a novel species in the genus Phlebopus (Boletinellaceae, Boletales). The new species resembles P. portentosus but differs from it in that mature basidiomata have a bright rose-red-colored stipe and a radiate tubular hymenophore with nested pores. Despite extensive searching, P. roseus has only been found at four sites within a 24-hectare orchard dominated by Eriobotrya japonica, which is agriculturally important given its fruit production (loquats). Therefore, this species appears to be endemic and geographically restricted. The ecology of this bolete is also unique. In line with the trophic behavior of other species in the Boletinellaceae, our observations indicate that P. roseus forms a symbiotic association with the scale insect Coccus hesperidum, identified through sequence analysis of its mitochondrial cytochrome c oxidase subunit I (COI) region, to form fungus-insect galls that develop on roots of E. japonica trees. Phlebopus roseus is an edible mushroom species and is collected from the type location by farmers and sold commercially in limited quantities at local markets alongside P. portentosus and other fungi. [ABSTRACT FROM AUTHOR]

The ITS1-5.8S-ITS2 rRNA (internal transcribed spacer (ITS)) region is used for examining the phylogenetic relationships of Rhizopogon roseolus and other closely related fungi belonging to Rhizopogon subgenus Roseoli in order to determine the genetic basis for phenotypic differences among R. roseolus isolates from different geographic regions. The ITS region is used for designing a multiplex PCR for the simultaneous identification of Japanese and New Zealand R. roseolus isolates in order to track the establishment of ectomycorrhiza on Pinaceae radiate seedlings inoculated with commercially valuable R. roseolus.

The cultivation of Lactarius deliciosus (saffron milk cap) in New Zealand began in 2002 when fruiting bodies were produced in an Otago plantation of Pinus radiata seedlings artificially mycorrhized by L. deliciosus. In 2007, 42 P. radiata seedlings mycorrhized by L. deliciosus under controlled conditions were planted in a grass field at Plant and Food Research (Lincoln, Canterbury). The effects of pine bark mulch application and initial degree of mycorrhization of seedlings were examined to determine their influence on tree growth, development of mycorrhizae (i.e. their multiplication on the root system and their degree of branching) and fruiting body production. Mulch application increased tree growth significantly over 4 years. High initial mycorrhization slightly stimulated tree growth over 2 years. The initial degree of mycorrhization was positively, but not strongly, related to the persistence and development of L. deliciosus mycorrhizae and rhizomorphs based on root sample analyses 2 years after planting. However, mulching strongly reduced the proportion of highly branched L. deliciosus mycorrhizae compared with poorly ramified ones. A positive correlation was observed between the fruiting of L. deliciosus and the development of mycorrhizae. Mulching delayed the onset of fruiting body production. In 2010, fruiting bodies were produced only from non-mulched trees with eight of these (38 %) producing a total of 12 fruiting bodies. In 2011, 19 non-mulched trees (90 %) and 9 mulched trees (45 %) produced 143 and 47 fruiting bodies, respectively, totalling 190 fruiting bodies. By 2012, 19 non-mulched trees (90 %) and 13 mulched trees (65 %) produced 333 and 236 fruiting bodies, respectively, totalling 569 fruiting bodies (c. 30 kg). This study presents new information on factors influencing the onset of fruiting and the development of yields in a plantation of P. radiata mycorrhized by L. deliciosus. Projected yields as high as c. 300 kg/ha from the third year of production reiterate the feasibility of farming saffron milk cap in P. radiata plantations in New Zealand. Continued monitoring of this site and development of similar trials will provide important knowledge for the optimisation of yields in commercial saffron milk cap orchards. [ABSTRACT FROM AUTHOR]