Study On Taxonomy And Life Cycle Of Unclear Rust Fungi In Jilin Province

The rust fungi are unique and interesting group of fungi classified in Pucciniales,Pucciniomycetes,Basidiomycota.Its name comes from the fact that rust sori are often orange or reddish-orange.Rust fungi are plant parasites which can live only on living plants and their relationships with plants are very important for their survival.They sometimes cause serious plant diseases in agricultures and forestry.Therefore,it is important to clarify their characteristics for their control and maintenance of ecological systems.However,their life cycles are very complicated because they produce five types of spore stages which are morphologically and functionally different each other and they also need two kind of unrelated plants to complete their life cycle.Furthermore,their taxonomy,especially in species level,is very confused because of complicated life cycles on host plants and morphological similarities among species.Clarification of their taxonomy and life cycles are very important to identify their species and to develop useful methods for their control based on sustainable ecological systems.Some lists or records of rust fungi in Jilin Province have been reported previously,but these are only accounts of collections in some areas and their species identifications are uncertain due to a lack of enough specimens and no accurate information of host plants and life cycles.Comprehensive study about taxonomy and life cycle of rust fungi in Jilin Province have not been reported until now.Therefore,occurrences of rust fungi have been surveyed at several areas in Jilin Province,which are geographically and climatically different each other and have different vegetations.Some groups of rust fungi have been frequently observed in Jilin Provinces.However,their taxonomy and life cycles have not been cleared.To clarify these problems morphological observations,identifications of host plants,inoculation experiments and phylogenetic analyses have been carried out based on specimens collected.Especially,molecular approaches have been very useful in this experiment to solve the problems of morphological similarities,host plant relations and connections of spore stages.The followings are results of experiments:(1)Two new species of Pucciniastrum producing dimorphic sori and sporesThe rust specimens on Galium(Rubiaceae),Aster,and Kalimeris(Compositae)were found in Jilin and Heilongjiang Provinces.Comparative morphology and phylogenetic analyses showed that these specimens belonged to Pucciniastrum.Therefore,the rust fungus on Galium and another on Aster and Kalimeris were described as P.coronisporum and P.verruculosum,respectively.Both new species were mainly characterized by having two types of uredinia producing morphologically different urediniospores,which were intermingled in most of the uredinia.(2)Life cycle of Pucciniastrum tiliaeLife cycle connection between spermogonial and aecial stages of a rust fungus found on Abies holophylla and uredinial and telial stages on Tilia mongolica and T.mandshurica collected in northeast of China were confirmed by phylogenetic analyses.The rust was identified as Pucciniastrum tiliae along with morphological observations.The life cycle of this rust fungus was reported for the first time in China and A.holophylla and T.mongolica are new host plants for the species.(3)Life cycle of Nothoravenelia japonica and its phylogenetic position in Pucciniales,with special reference to the genus PhakopsoraThe autoecious macrocyclic life cycle of Nothoravenelia japonica on Flueggea suffruticosa was clarified by inoculations.The morphology of each stage was described based on specimens obtained from inoculations.The description of the genus was also emended.Phylogenetic analyses showed that this rust fungus was closely related to one group of Phakopsora,but far from a second group.Therefore,it was suggested that the genus Phakopsora should be divided into two genera.The second group was treated as new genus Neophysopella based on morphological and phylogenetical similarities and host relations.Nine new combinations of Neophysopella;N.ampelopsidis,N.hornotina,N.meliosmae,N.meliosmae-myrianthae,N.montana,N.muscadinae,N.orientalis,N.uva,and N.vitis were proposed.(4)Life cycle and taxonomy of Chrysomyxa succineaRust diseases of spruce and rhododendrons caused by Chrysomyxa succinea are commonly observed in forests of northern and eastern Asia.The heteroecious life cycle of this species alternating between spermogonial and aecial stages on Picea jezoensis and uredinial and telial stages on Rhododendron aureum was confirmed for the first time in China by inoculations and phylogenetic analyses.Morphological characters of all stages were described based on specimens obtained from the field and from inoculations.Based on morphological similarities and phylogenetic analyses,Ch.zhouniensis reported on Picea asperata was treated as a synonym of Ch.succinea.(5)Taxonomy and life cycle of Puccinia species on Poaceae and CyperaceaeMany clades considered as species were detected among specimens and life cycle connections were clarified in many species.Puccinia species on Poaceae and Cyperaceae were showed to be developed separately,and spermogonial and aecial host plants are different between these groups.Among Puccinia species on Poaceae,life cycle of 14 species were clarified,among them life cycle of P.caulophylli was confirmed for the first time,life cycles of P.rangiferina,P.coronata var.coronate,P.festucae,P.striiformis,P.magnusiana,P.miscanthi,P.phragmitis were confirmed for the first time in China;two new record species: P.coronati-agrostidis,P.coronati-hordei were found in China;and proposed 7 new species.Among Puccinia species on Cyperaceae,life cycle of 11 species were clarified,among them life cycle of P.circaeae-caricis,P.caricis and P.caricis-molliculae were confirmed for the first time in China;and proposed 10 new species.Based on the phylogenetic relationships,it was suspected that some species were differentiated from spermogonial and aecial stages on same group of host plants in their evolution.Host specificity in uredinial and telial stages was also confirmed although host jumping was showed in some species.In this study,species delimitations,life cycle,host plants,phylogenetic relationships,evolutionary trends of rust fungi distributed in Jilin Province were clearly demonstrated.Many cryptic species and their life cycles were also newly found.It is showed that species diversity of rust fungi in Jilin Province are very rich and they have life cycles and host relations adapted in environmental conditions of Jilin Province.These results are very important and contribute for research developments on taxonomy,phylogeny,life cycle and evolution of rust fungi.