Comparative transcriptome analysis reveals candidate genes related to cadmium accumulation and tolerance in two almond mushroom (Agaricus brasiliensis) strains with contrasting cadmium tolerance.

Cadmium (Cd) is a toxic metal occurring in the environment naturally. Almond mushroom (Agaricus brasiliensis) is a well-known cultivated edible and medicinal mushroom. In the past few decades, Cd accumulation in A.brasiliensis has received increasing attention. However, the molecular mechanisms of Cd-accumulation in A. brasiliensis are still unclear. In this paper, a comparative transcriptome of two A.brasiliensis strains with contrasting Cd accumulation and tolerance was performed to identify Cd-responsive genes possibly responsible for low Cd-accumulation and high Cd-tolerance. Using low Cd-accumulating and Cd-tolerant (J77) and high Cd-accumulating and Cd-sensitive (J1) A.brasiliensis strains, we investigated 0, 2 and 5 mg L-1 Cd-effects on mycelium growth, Cd-accumulation and transcriptome revealed by RNA-Seq. A total of 57,884 unigenes were obtained. Far less Cd-responsive genes were identified in J77 mycelia than those in J1 mycelia (e.g., ABC transporters, ZIP Zn transporter, Glutathione S-transferase and Cation efflux (CE) family). The higher Cd-accumulation in J1 mycelia might be due to Cd-induced upregulation of ZIP Zn transporter. Cd impaired cell wall, cell cycle, DNA replication and repair, thus decreasing J1 mycelium growth. Cd-stimulated production of sulfur-containing compounds, polysaccharides, organic acids, trehalose, ATP and NADPH, and sequestration of Cd might be adaptive responses of J1 mycelia to the increased Cd-accumulation. DNA replication and repair had better stability under 2 mg L-1 Cd, but greater positive modifications under 5 mg L-1 Cd. Better stability of DNA replication and repair, better cell wall and cell cycle stability might account for the higher Cd-tolerance of J77 mycelia. Our findings provide a comprehensive set of DEGs influenced by Cd stress; and shed light on molecular mechanism of A.brasiliensis Cd accumulation and Cd tolerance.

[Effects of biochar and sheep manure on rhizospheric soil microbial community in continuous ratooning tea orchards]. / æ–½ç”¨ç”Ÿç‰©è´¨ç‚­å’Œç¾Šç²ªå¯¹å®¿æ ¹è¿žä½œèŒ¶å›­æ ¹é™ åœŸå£¤å¾®ç”Ÿç‰©çš„å½±å“.

Long-term continuous ratooning of tea could lead to serious soil acidification, nutritional imbalance, and the deterioration of the rhizosphere micro-ecological environment. Understanding the effects of biochar and sheep manure on the growth of tea plants and the rhizosphere microbial community structure and function would provide theoretical basis to improve the soil micro-ecological environment of continuous ratooning tea orchards. Biolog technology combined with phospholipid fatty acid (PLFA) approaches were employed to quantify the effects of biochar (40 t·hm-2) and sheep manure on the growth of 20 years continuous ratooning tea plants, soil chemical properties, and the soil microbial community structure and function. The results showed that after one year treatment, biochar and sheep manure both improved soil pH and nutrition, and significantly enhanced tea production. Compared with the routine fertilizer application (CK), the biochar and sheep manure treatments significantly increased the carbon metabolic activity (AWCD) and microorganism diversity in the rhizosphere soils, and increased the relative utilization of the carbon sources such as amines, carbohydrates, and polymers. The total PLFA concentrations in the biochar and sheep manure treatments were significantly increased by 20.9% and 47.5% than that in the routine fertilizers application. In addition, sheep manure treatment significantly decreased the saturated/monosaturated fatty acids In conclusion, biochar and sheep manure could alleviate soil acidification, enhance soil nutrition and the growth of tea plants. Both management strategies could increase the soil microbial activity and biomass, enhance the diversity, and improve the microbial community structure, which could be taken as effective measures to regulate the rhizosphere micro-environment of tea plants.

[Effects of vegetation restoration on soil carbon and nitrogen cycles: a review].

Vegetation rehabilitation is one of the main means in managing soil and water loss, being able to effectively promote the development of eroded soil, improve the soil fertility level, enhance the soil microbial activities, and in further, affect the soil carbon and nitrogen cycles. Therefore, vegetation rehabilitation plays definite roles in the accumulation of soil organic carbon and nitrogen pools and the mitigation of greenhouse gases emission from soil. This paper summarized the effects of vegetation rehabilitation on the soil carbon and nitrogen cycles and the synergetic effects between soil quality and vegetation rehabilitation, and put forward the further research directions, which could provide the reference for the evaluation of the roles of vegetation rehabilitation in response to global climate change, and the practical guidance for the improvement of soil fertility and the recovery and sustainable development of degraded ecosystems.