Salicylic Acid Enhances Heat Stress Resistance of Pleurotus ostreatus (Jacq.) P. Kumm through Metabolic Rearrangement.

Pleurotus ostreatus (Jacq.) P. Kumm is cultivated worldwide, and its growth is seriously threatened by heat stress. Here, we performed a comprehensive analysis to investigate the influence of the phytohormone salicylic acid (SA) in P. ostreatus under HS. The results showed that the hyphal growth recovery rate and the antioxidant capacity of P. ostreatus increased with exogenous SA application (0.01 mmol/L and 0.05 mmol/L) after HS treatment. Metabolomic and transcriptomic analyses showed that SA application (0.05 mmol/L) weakened central carbon metabolism to allow cells to survive HS efficiently. In addition, SA shifted glycolysis to one-carbon metabolism to produce ROS scavengers (GSH and NADPH) and reduced ROS production by altering mitochondrial metabolism. SA also maintained nucleotide homeostasis, led to membrane lipid remodeling, activated the MAPK pathway, and promoted the synthesis of cell-wall components. This study provides a reference for further study of SA in microorganisms.

[Comparisons of different methods for virus-elimination of edible fungi].

Four dsRNA bands were extracted from Pleurotus ostreatus TD300 by the dsRNA isolation technique with sizes of 8.2 kb, 2.5 kb, 2.1 kb, and 1.1 kb, respectively. Four virus-eliminated methods, i. e. hyphal tips cut (HTC), protoplast regeneration (PR), single spore hybridization (SSH), and frozen and lyophilized (FL), were applied to prepare virus-eliminated strains, and one virus-eliminated strain was selected for each virus-elimination method. The virus-eliminated strains were named as HTC8, PR15, FL01, and SSH11, respectively. There were low concentration of 8.2 kb dsRNA remained in HTC8, as well as low concentration of 8.2 kb and 2.5 kb dsRNA remained in FL01. However, no dsRNA remained in PR15 and SSH11. The hyphal growth rate and laccase activity of the virus-eliminated strains increased, especially HTC8 and PR15, whose hyphal growth rate was higher by 22.73% and 18.18%, and laccase activities higher by 145.83% and 134.38% than that of the original strain, respectively. The conclusion is that hyphal tips cut and protoplast regeneration are suitable to prepare virus-eliminated strains of edible fungi.

[Overexpression of GST gene accelerates the growth of transgenic Arabidopsis under salt stress].

The Suaeda salsa glutathione s-transferase gene (GST) was inserted downstream of the 35S promoter in the plant expression vector pROK II and then was introduced into Arabidopsis thaliana by Agrobacterium tumefaciens through floral dip method. Transformants were selected for their ability to grow on medium containing kanamycin. The fact that the GST gene had been transferred into the Arabidopsis thaliana genome was confirmed by the PCR-Southern blotting analysis. After cultivation, independent homozygous transgenic lines were obtained after selection of T(3) progenies on MS medium containing kanamycin. The expression of the gene transferred into the Arabidopsis thaliana was confirmed by Northern blotting. During salt stress, analysis of total glutathione (both oxidized and reduced type) and biomass of transgenic and wild Arabidopsis. The biomass of transgenic lines (GT) was slightly but significantly greater than that of wild type line (WT), and levels of oxidized glutathione (GSSG) were significantly higher in transgenic lines than in wild type. Therefore, overexpression of GST can increase Arabidopsis growth under salt stress, and this effect can be caused by oxidation of the reduced glutathione (GSH ).