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Arabidopsis RESISTANCE TO POWDERY MILDEW 8.2 (RPW8.2) is specifically induced by the powdery mildew (PM) fungus (Golovinomyces cichoracearum) in the infected epidermal cells to activate immunity. However, the mechanism of RPW8.2-induction is not well understood. Here, we identify a G. cichoracearum effector that interacts with RPW8.2, named Gc-RPW8.2 interacting protein 1 (GcR8IP1), by a yeast two-hybrid screen of an Arabidopsis cDNA library. GcR8IP1 physically associated with RPW8.2 with its RING finger domain that is essential and sufficient for the association. GcR8IP1 was secreted and translocated into the nucleus of host cell infected with PM. Association of GcR8IP1 with RPW8.2 led to an increase of RPW8.2 in the nucleus. In turn, the nucleus-localised RPW8.2 promoted the activity of the RPW8.2 promoter, resulting in transcriptional self-amplification of RPW8.2 to boost immunity at infection sites. Additionally, ectopic expression or host-induced gene silencing of GcR8IP1 supported its role as a virulence factor in PM. Altogether, our results reveal a mechanism of RPW8.2-dependent defense strengthening via altered partitioning of RPW8.2 and transcriptional self-amplification triggered by a PM fungal effector, which exemplifies an atypical form of effector-triggered immunity. 

As the continuation of Fungal Diversity Notes series, the current paper is the 16th contribution to this series. A total of 103 taxa from seven classes in Ascomycota and Basidiomycota are included here. Of these 101 taxa, four new genera, 89 new species, one new combination, one new name and six new records are described in detail along with information of hosts and geographic distributions. The four genera newly introduced are Ascoglobospora, Atheliella, Rufoboletus and Tenuimyces. Newly described species are Akanthomyces xixiuensis, Agaricus agharkarii, A. albostipitatus, Amphisphaeria guttulata, Ascoglobospora marina, Astrothelium peudostraminicolor, Athelia naviculispora, Atheliella conifericola, Athelopsis subglaucina, Aureoboletus minimus, A. nanlingensis, Autophagomyces incertus, Beltrania liliiferae, Beltraniella jiangxiensis, Botryobasidium coniferarum, Calocybella sribuabanensis, Calonarius caesiofulvus, C. nobilis, C. pacificus, C. pulcher, C. subcorrosus, Cortinarius flaureifolius, C. floridaensis, C. subiodes, Crustomyces juniperi, C. scytinostromoides, Cystostereum subsirmaurense, Dimorphomyces seemanii, Fulvoderma microporum, Ginnsia laricicola, Gomphus zamorinorum, Halobyssothecium sichuanense, Hemileccinum duriusculum, Henningsomyces hengduanensis, Hygronarius californicus, Kneiffiella pseudoabdita, K. pseudoalutacea, Laboulbenia bifida, L. tschirnhausii, L. tuberculata, Lambertella dipterocarpacearum, Laxitextum subrubrum, Lyomyces austro-occidentalis, L. crystallina, L. guttulatus, L. niveus, L. tasmanicus, Marasmius centrocinnamomeus, M. ferrugineodiscus, Megasporoporia tamilnaduensis, Meruliopsis crystallina, Metuloidea imbricata, Moniliophthora atlantica, Mystinarius ochrobrunneus, Neomycoleptodiscus alishanense, Nigrograna kunmingensis, Paracremonium aquaticum, Parahelicomyces dictyosporus, Peniophorella sidera, P. subreticulata, Phlegmacium fennicum, P. pallidocaeruleum, Pholiota betulicola, P. subcaespitosa, Pleurotheciella hyalospora, Pleurothecium aseptatum, Resupinatus porrigens, Russula chlorina, R. chrysea, R. cruenta, R. haematina, R. luteocarpa, R. sanguinolenta, Synnemellisia punensis, Tenuimyces bambusicola, Thaxterogaster americanoporphyropus, T. obscurovibratilis, Thermoascus endophyticus, Trechispora alba, T. perminispora, T. subfarinacea, T. tuberculata, Tremella sairandhriana, Tropicoporus natarajaniae, T. subramaniae, Usnea kriegeriana, Wolfiporiella macrospora and Xylodon muchuanensis. Rufoboletus hainanensis is newly transferred from Butyriboletus, while a new name Russula albocarpa is proposed for Russula leucocarpa G.J. Li & Chun Y. Deng an illegitimate later homonym of Russula leucocarpa (T. Lebel) T. Lebel. The new geographic distribution regions are recorded for Agaricus bambusetorum, Bipolaris heliconiae, Crinipellis trichialis, Leucocoprinus cretaceus, Halobyssothecium cangshanense and Parasola setulosa. Corresponding to morphological characters, phylogenetic evidence is also utilized to place the above-mentioned taxa in appropriate taxonomic positions. The current morphological and phylogenetic data is helpful for further clarification of species diversity and exploration of evolutionary relationships in the related fungal groups.