Mitogen-Activated Protein Kinases SvPmk1 and SvMps1 Are Critical for Abiotic Stress Resistance, Development and Pathogenesis of Sclerotiophoma versabilis.

Mitogen-activated protein kinase (MAPK) signaling pathways are evolutionarily conserved in eukaryotes and modulate responses to both internal and external stimuli. Pmk1 and Mps MAPK pathways regulate stress tolerance, vegetative growth and cell wall integrity in Saccharomyces cerevisiae and Pyricularia oryzae. Here, we deployed genetic and cell biology strategies to investigate the roles of the orthologs of Pmk1 and Mps1 in Sclerotiophoma versabilis (herein referred to as SvPmk1 and SvMps1, respectively). Our results showed that SvPmk1 and SvMps1 are involved in hyphal development, asexual reproduction and pathogenesis in S. versabilis. We found that ∆Svpmk1 and ∆Svmps1 mutants have significantly reduced vegetative growths on PDA supplemented with osmotic stress-inducing agents, compared to the wild type, with ∆Svpmps1 being hypersensitive to hydrogen peroxide. The two mutants failed to produce pycnidia and have reduced pathogenicity on Pseudostellaria heterophylla. Unlike SvPmk1, SvMps1 was found to be indispensable for the fungal cell wall integrity. Confocal microscopic analyses revealed that SvPmk1 and SvMps1 are ubiquitously expressed in the cytosol and nucleus. Taken together, we demonstrate here that SvPmk1 and SvMps1 play critical roles in the stress resistance, development and pathogenesis of S. versabilis.

Screening of biocontrol bacteria against soft rot disease of Colocasia esculenta (L.) schott and its field application.

Soft rot disease is a major pathogenic bacteria of Fuding areca taro and has caused serious losses. This study aims to screen biocontrol bacterial against soft rot disease. A total of 53 bacterial strains were isolated from the rhizosphere soil, nine of which exhibited good biocontrol effect against the pathogenic bacteria of soft rot disease as seen in antagonistic screening of biocontrol bacteria from corm in vitro. Strains were selected by physical and chemical experiments, biocontrol effect tests in vivo, molecular sequencing, morphological observation and field tests. Four strains including CAB-L005, CAB-L012, CAB-L014, and CAB-L022 exhibited strong antagonistic effects. On the basis of the sequence homology of 16S rRNA genes, the similarity between strain CAB-L005 and Bacillus tropicus was 100%, that between strain CAB-L012 and Bacillus subtilis was 99%, and that between strain CAB-L014 and Bacillus tequilensis was 100%, and similarity between strain CAB-L022 and Bacillus cereus was 100%. The isolated bacteria demonstrated good biocontrol effects in field experiments. In this study, four strains with good biocontrol application value were isolated and identified, providing a foundation for biocontrol against soft rot disease in areca taro.

Long-Read Genome Sequence Resource of Ascochyta versabilis Causing Leaf Spot Disease in Pseudostellaria heterophylla.

Ascochyta versabilis is the fungal pathogen that causes the severe leaf spot disease of Pseudostellaria heterophylla (Miq.) Pax, a vital Chinese herbal plant. Here, we deployed PacBio single-molecule real-time long-read sequencing technology to generate a near-complete genome assembly for the A. versabilis KC1 strain and obtained a total of 9.80 Gb raw reads. These reads were processed into a 41.05 Mb genome assembly containing 95 contigs with N50 of 1.70 Mb and a maximum length of 3.93 Mb. A total of 10,457 gene models, of which 1,004 encode putatively secreted proteins, were identified in the genome. This high-quality genome assembly and gene annotation resource will facilitate the institution of functional genetic studies aimed at providing a better insight into the infection mechanisms of A. versabilis to support the development of effective control strategies for leaf spot disease of P. heterophylla.

Responses of Different Cancer Cells to White Tea Aqueous Extract.

White tea from the eastern Chinese province of Fujian is a unique tea variety. Although the health effects of various teas have been investigated in recent years, most studies focused exclusively on green tea varieties. In order to study effects exerted by white tea from eastern Fujian on the viability of cancer cells, we analyzed its main bioactive ingredients. We also evaluated the antioxidant activity of white tea aqueous extract (WTAE) and employed MTT assay to evaluate effects of WTAE on viabilities of Hela and BEL-7402 cancer cell lines. Apoptosis rate detection was also applied to estimate efficacy of cellular apoptotic induction by WTAE in these two cells types. Results revealed that WTAE exhibited high antioxidant activity and inhibited effectively the proliferation of Hela and BEL-7402 cells. The half maximal inhibitory concentration (IC50) of WTAE for Hela cells (0.05 mg/mL) was lower than that for BEL-7402 cells (0.1 mg/mL). Although WTAE induced apoptosis in both cell lines, pro-apoptotic effects were markedly more apparent in Hela cells. Our study demonstrated that WTAE inhibited proliferation of cancer cells via induction of apoptosis and that Hela cells were more sensitive to WTAE than BEL-7402 cells. PRACTICAL APPLICATION: The aim of this study is to provide a new approach toward cancer prevention by consuming white tea, the properties of which may also be helpful in formulating novel anticancer therapeutics.