The genus Lentinus (Polyporaceae, Basidiomycota) is widely documented from tropical and temperate forests and is taxonomically controversial. Here we studied the relationships between Lentinus subg. Lentinus sensu Pegler (i.e. sections Lentinus, Tigrini, Dicholamellatae, Rigidi, Lentodiellum and Pleuroti and polypores that share similar morphological characters). We generated sequences of internal transcribed spacers (ITS) and partial 28S regions of nuc rDNA and genes encoding the largest subunit of RNA polymerase II (RPB1), focusing on Lentinus subg. Lentinus sensu Pegler and the Neofavolus group, combined these data with sequences from GenBank (including RPB2 gene sequences) and performed phylogenetic analyses with maximum likelihood and Bayesian methods. We also evaluated the transition in hymenophore morphology between Lentinus, Neofavolus and related polypores with ancestral state reconstruction. Single-gene phylogenies and phylogenies combining ITS and 28S with RPB1 and RPB2 genes all support existence of a Lentinus/Polyporellus clade and a separate Neofavolus clade. Polyporellus (represented by P. arcularius, P. ciliatus, P. brumalis) forms a clade with species representing Lentinus subg. Lentinus sensu Pegler (1983), excluding L. suavissimus. Lentinus tigrinus appears as the sister group of Polyporellus in the four-gene phylogeny, but this placement was weakly supported. All three multigene analyses and the single-gene analysis using ITS strongly supported Polyporus tricholoma as the sister group of the Lentinus/Polyporellus clade; only the 28S rRNA phylogeny failed to support this placement. Under parsimony the ancestral hymenophoral configuration for the Lentinus/Polyporellus clade is estimated to be circular pores, with independent transitions to angular pores and lamellae. The ancestral state for the Neofavolus clade is estimated to be angular pores, with a single transition to lamellae in L. suavissimus. We propose that Lentinus suavissimus (section Pleuroti) should be reclassified as Neofavolus suavissimus comb. nov.
Lignosus rhinocerotis (Cooke) Ryvarden (Polyporales, Basidiomycota), also known as the tiger milk mushroom, has received much interest in recent years owing to its wide-range ethnobotanical uses and the recent success in its domestication. The sclerotium is the part with medicinal value. Using two-dimensional gel electrophoresis coupled with mass spectrometry analysis, a total of 16 non-redundant, major proteins were identified with high confidence level in L. rhinocerotis sclerotium based on its genome as custom mapping database. Some of these proteins, such as the putative lectins, immunomodulatory proteins, superoxide dismutase, and aegerolysin may have pharmaceutical potential; while others are involved in nutrient mobilization and the protective antioxidant mechanism in the sclerotium. The findings from this study provide a molecular basis for future research on potential pharmacologically active proteins of L. rhinocerotis.
A lectin gene from the Tiger Milk Mushroom Lignosus rhinocerus TM02® was successfully cloned and expressed via vector pET28a in Escherichia coli BL21(DE3). The recombinant lectin, Rhinocelectin, with a predicted molecular mass of 22.8 kDa, was overexpressed in water-soluble form without signal peptide and purified via native affinity chromatography Ni-NTA agarose. Blast protein analysis indicated the lectin to be homologous to jacalin-related plant lectin. In its native form, Rhinocelectin exists as a homo-tetramer predicted with four chains of identical proteins consisting of 11 beta-sheet structures with only one alpha-helix structure. The antiproliferative activity of the Rhinocelectin against human cancer cell lines was concentration dependent and selective. The IC50 values against triple negative breast cancer cell lines MDA-MB-231 and breast cancer MCF-7 are 36.52 ± 13.55 μg mL-1 and 53.11 ± 22.30 μg mL-1 , respectively. Rhinocelectin is only mildly cytotoxic against the corresponding human nontumorigenic breast cell line 184B5 with IC50 value at 142.19 ± 36.34 μg mL-1 . The IC50 against human lung cancer cell line A549 cells is 46.14 ± 7.42 μg mL-1 while against nontumorigenic lung cell line NL20 is 41.33 ± 7.43 μg mL-1 . The standard anticancer drug, Doxorubicin exhibited IC50 values mostly below 1 μg mL-1 for the cell lines tested. Flow cytometry analysis showed the treated breast cancer cells were arrested at G0/G1 phase and apoptosis induced. Rhinocelectin agglutinated rat and rabbit erythrocytes at a minimal concentration of 3.125 μg mL-1 and 6.250 μg mL-1 , respectively.