Jiang-Chun Wei

Ambuic Acid and Torreyanic Acid Derivatives from the Endolichenic Fungus Pestalotiopsis sp.

Six new ambuic acid (1) derivatives (2-7) and a new torreyanic acid analogue (8) have been isolated from the crude extract of endophytic fungus Pestalotiopsis sp. inhabiting the lichen Multiclavula [corrected] sp. The structures of these compounds were elucidated primarily by NMR and MS methods, and their absolute configurations were assigned by application of the CD excitation chirality method. Compounds 1 and 2 displayed antimicrobial activity against the Gram-positive bacterium Staphylococcus aureus.

Survival analyses of symbionts isolated from Endocarpon pusillum Hedwig to desiccation and starvation stress

This work deals with the survival analyses of the symbionts isolated from the lichen E. pusillum under desiccation and starvation stress. The mycobiont of the symbionts was under the desiccation in combination with starvation stress, and under starvation stress alone as well. The phycobiont of the symbionts was under desiccation stress alone. The experiments were detected by means of the biomass size, weight and cell density, deformity of the hyphae and cells, and metabolic activity through SEM (scanning electron microscopy), TEM (transmission electron microscopy), FM (fluorescence microscopy), spectrophotometry, and FCM (flow cytometry). The results show that the mycobiont can survive for seven months under desiccation stress in combination with starvation stress, and for eight months under starvation stress alone. The phycobiont can survive for two months under desiccation stress. It can provide a scientific basis for further research of the reproduction biology of lichens and arid desert biocarpet engineering to fix sand and carbon.

Effects of irradiance on growth, photosynthetic characteristics, and artemisinin content of Artemisia annua L.

With an increase in growth irradiance (from 15 to 100 % of full sunlight, I15 to I100), the maximum net photosynthetic rate (Pmax), compensation (CI) and saturation irradiances of A. annua increased. At full sunlight, A. annua had a high capacity of photosynthesis, while at low irradiance it maintained a relatively high Pmax with a low CI. The height and diameter growth, total and leaf biomass, and artemisinin content of A. annua decreased with the decrease in irradiance, which might be connected with lower photosynthesis at lower than at higher irradiance. Irradiances changed biomass allocations of A. annua. The leaf/total mass ratio of A. annua increased with decreasing irradiance, but the root/total mass ratio and root/above-ground mass generally increased with increasing irradiance. Thus A. annua can grow in both weak and full sunlight. However, high yield of biomass and artemisinin require cultivation in an open habitat with adequate sunshine.

Ascomycota has a faster evolutionary rate and higher species diversity than Basidiomycota

Differences in rates of nucleotide or amino acid substitutions among major groups of organisms are repeatedly found and well documented. A growing body of evidence suggests a link between the rate of neutral molecular change within populations and the evolution of species diversity. More than 98% of terrestrial fungi belong to the phyla Ascomycota or Basidiomycota. The former is considerably richer in number of species than the latter. We obtained DNA sequences of 21 protein-coding genes from the lichenized fungus Rhizoplaca chrysoleuca and used them together with sequences from GenBank for subsequent analyses. Three datasets were used to test rate discrepancies between Ascomycota and Basidiomycota and that within Ascomycota: (i) 13 taxa including 105 protein-coding genes, (ii) nine taxa including 21 protein-coding genes, and (iii) nuclear LSU rDNA of 299 fungal species. Based on analyses of the 105 protein-coding genes and nuclear LSU rDNA datasets, we found that the evolutionary rate was higher in Ascomycota than in Basidiomycota. The differences in substitution rates between Ascomycota and Basidiomycota were significant. Within Ascomycota, the species-rich Sordariomycetes has the fastest evolutionary rate, while Leotiomycetes has the slowest. Our results indicate that the main contribution to the higher substitution rates in Ascomycota does not come from mutualism, ecological conditions, sterility, metabolic rate or shorter generation time, but is possibly caused by the founder effect. This is another example of the correlation between species number and evolutionary rates, which is consistent with the hypothesis that the founder effect is responsible for accelerated substitution rates in diverse clades.

Comparative transcriptome analysis of the lichen-forming fungus Endocarpon pusillum elucidates its drought adaptation mechanisms

The lichen-forming fungus was isolated from the desert lichen Endocarpon pusillum that is extremely drought resistant. To understand the molecular mechanisms of drought resistance in the fungus, we employed RNA-seq and quantitative real-time PCR to compare and characterize the differentially expressed genes in pure culture at two different water levels and with that in desiccated lichen. The comparative transcriptome analysis indicated that a total of 1781 genes were differentially expressed between samples cultured under normal and PEG-induced drought stress conditions. Similar to those in drought resistance plants and non-lichenized fungi, the common drought-resistant mechanisms were differentially expressed in E. pusillum. However, the expression change of genes involved in osmotic regulation in E. pusillum is different, which might be the evidence for the feature of drought adaptation. Interestingly, different from other organisms, some genes involved in drought adaption mechanisms showed significantly different expression patterns between the presence and absence of drought stress in E. pusillum. The expression of 23 candidate stress responsive genes was further confirmed by quantitative real-time PCR using dehydrated E. pusillum lichen thalli. This study provides a valuable resource for future research on lichen-forming fungi and shall facilitate future functional studies of the specific genes related to drought resistance.

Lichen-Associated Fungal Community in Hypogymnia hypotrypa (Parmeliaceae, Ascomycota) Affected by Geographic Distribution and Altitude.

Lichen-associated fungal species have already been investigated in almost all the main growth forms of lichens, however, whether or not they are homogeneous and constant within each lichen species are still inconclusive. Moreover, the related ecological factors to affect and structure the fungal composition have been poorly studied. In order to answer these questions, we took Hypogymnia hypotrypa as a model to study the relationship between the lichen-associated fungal composition and two ecological factors, i.e., site and altitude, using the method of IlluminaMiSeq sequencing. Four different sites and two levels of altitude were included in this study, and the effects of site and altitude on fungal community composition were assessed at three levels, i.e., operational taxonomic unit (OTU), class and phylum. The results showed that a total of 50 OTUs were identified and distributed in 4 phyla, 13 classes, and 20 orders. The lichen-associated fungal composition within H. hypotrypa were significantly affected by both site and altitude at OTU and class levels, while at the phylum level, it was only affected by altitude. While the lichen associated fungal communities were reported to be similar with endophytic fungi of the moss, our results indicated the opposite results in some degree. But whether there exist specific OTUs within this lichen species corresponding to different sites and altitudes is still open. More lichen species and ecological factors would be taken into the integrated analyses to address these knowledge gaps in the near future.

Limitations of Species Delimitation Based on Phylogenetic Analyses: A Case Study in the Hypogymnia hypotrypa Group (Parmeliaceae, Ascomycota).

Delimiting species boundaries among closely related lineages often requires a range of independent data sets and analytical approaches. Similar to other organismal groups, robust species circumscriptions in fungi are increasingly investigated within an empirical framework. Here we attempt to delimit species boundaries in a closely related clade of lichen-forming fungi endemic to Asia, the Hypogymnia hypotrypa group (Parmeliaceae). In the current classification, the Hypogymnia hypotrypa group includes two species: H. hypotrypa and H. flavida, which are separated based on distinctive reproductive modes, the former producing soredia but absent in the latter. We reexamined the relationship between these two species using phenotypic characters and molecular sequence data (ITS, GPD, and MCM7 sequences) to address species boundaries in this group. In addition to morphological investigations, we used Bayesian clustering to identify potential genetic groups in the H. hypotrypa/H. flavida clade. We also used a variety of empirical, sequence-based species delimitation approaches, including: the “Automatic Barcode Gap Discovery” (ABGD), the Poisson tree process model (PTP), the General Mixed Yule Coalescent (GMYC), and the multispecies coalescent approach BPP. Different species delimitation scenarios were compared using Bayes factors delimitation analysis, in addition to comparisons of pairwise genetic distances, pairwise fixation indices (FST). The majority of the species delimitation analyses implemented in this study failed to support H. hypotrypa and H. flavida as distinct lineages, as did the Bayesian clustering analysis. However, strong support for the evolutionary independence of H. hypotrypa and H. flavida was inferred using BPP and further supported by Bayes factor delimitation. In spite of rigorous morphological comparisons and a wide range of sequence-based approaches to delimit species, species boundaries in the H. hypotrypa group remain uncertain. This study reveals the potential limitations of relying on distinct reproductive strategies as diagnostic taxonomic characters for Hypogymnia and also the challenges of using popular sequence-based species delimitation methods in groups with recent diversification histories.

Estimation of Endocarpon pusillum Hedwig carbon budget in the Tengger Desert based on its photosynthetic rate

This study investigated the photosynthetic rate of the lichen Endocarpon pusillum at the Chinese Academy of Sciences Shapotou Desert Research Station and estimated its annual contribution to the carbon budget in the ecosystem. The software SigmaPlot 10.0 with “Macro-Area below curves” was used to calculate the carbon fixation capacity of the lichen. The total carbon budget (ΣC) of the lichen was obtained by subtracting the respiratory carbon loss (ΣDR) from the photosynthetic carbon gain (ΣNP). Because water from precipitation plays an important role in photosynthesis in this ecosystem, the annual carbon budget of E. pusillum at the station was estimated based on the three-year average precipitation data from 2009 to 2011. Our results indicate that the lichen fixes 14.6 g C m−2 annually. The results suggest that artificial inoculation of the crust lichen in the Tengger Desert could not only help reduce the sand and dust storms but also offer a significant carbon sink, fixing a total of 438000 t of carbon over the 30000 km2 of the Tengger Desert. The carbon sink could potentially help mitigate the atmospheric greenhouse effect. Our study suggests that the carpet-like lichen E. pusillum is an excellent candidate for “Bio-carpet Engineering” of arid and semi-arid regions.

Caloplaca tianshanensis (lichen-forming Ascomycota), a new species of subgenus Pyrenodesmia from China

Caloplaca tianshanensis is described as a species new to science. It has a crustose and areolate thallus of yellowish-brown color with conspicuous cracks, bearing dark brown to black apothecia. An analysis of ITS sequences supports the affinity of the new species to subgenus Pyrenodesmia .

Hypogymnia magnifica (Parmeliaceae), a new lichen from southwest China

Abstract Hypogymnia magnifica X.L.Wei & McCune is described as a new species of lichenized fungi from high elevations in Yunnan and Sichuan Provinces in southwestern China. Previously lumped under H. taiwanalpina, H. magnifica is readily distinguished from that species by its large size (commonly to 30 cm or more diam.), broad, rather appressed lobes that are contiguous to subcontiguous, sparse perforations in the upper and lateral surfaces, whitish color in the field (when dry), and lacking 3-hydroxyphysodic acid. Hypogymnia magnifica and H. taiwanalpina appear to be allopatric, with the former restricted to southwestern China and the latter restricted to far-east Asia (Taiwan and Japan).