Pore size and organic carbon of biochar limit the carbon sequestration potential of Bacillus cereus SR.

Carbon-fixing functional strain-loaded biochar may have significant potential in carbon sequestration given the global warming situation. The carbon-fixing functional strain Bacillus cereus SR was loaded onto rice straw biochar pyrolyzed at different temperatures with the anticipation of clarifying the carbon sequestration performance of this strain on biochar and the interaction effects with biochar. During the culture period, the content of dissolved organic carbon (DOC), easily oxidizable organic carbon, and microbial biomass carbon in biochar changed. This finding indicated that B. cereus SR utilized organic carbon for survival and enhanced carbon sequestration on biochar to increase organic carbon, manifested by changes in CO2 emissions and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) enzyme activity. Linear regression analysis showed that the strain was likely to consume DOC on 300 °C biochar, although the Rubisco enzyme activity was higher. In contrast, the strain had a higher carbon sequestration potential on 500 °C biochar. Correlation analysis showed that Rubisco enzyme activity was controlled by the physical structure of the biochar. Our results highlight the differences in the survival mode and carbon sequestration potential of B. cereus SR on biochar pyrolyzed at different temperatures.

Sequencing and phylogenetic characterization of a novel RNA virus in Arma chinensis.

The complete genome of a novel virus from Arma chinensis was determined by RNA sequencing and rapid amplification of cDNA ends. This virus has a single-stranded RNA genome of 10,540 nucleotides (nt) excluding the poly(A) tail. Two non-overlapping open reading frames (ORFs) in the sense direction were predicted: one long ORF at the 5' end of the genome (6,219 nt) that encodes a polypeptide of 2,072 amino acids (aa), and one short ORF at the 3' end of the genome (3,033 nt) that encodes a polypeptide of 1,010 aa. Phylogenetic analysis indicated that the virus clusters within a large cluster of currently unidentified picorna-like viruses with a high bootstrap value. We named the virus isolate Arma chinensis picorna-like virus 1 (AcPV-1). The prevalence of AcPV-1 infection in samples of Arma chinensis from the wild was at a low level (5.48%, 8 positives in 146 samples). Keywords: Arma chinensis; genomic characterization; phylogenetic analysis; Arma chinensis picorna-like virus 1; prevalence.

Sequencing and phylogenetic characterization of a novel RNA virus genome from Harmonia axyridis.

As a natural predator of many insect pests on its native Asian range, Harmonia axyridis remains amongst the insects whose pathogenic or beneficial microorganisms are yet to be studied. The genome nucleotide (nt) and amino acid sequences of open reading frames (ORFs) of the novel RNA virus were identified. Neighbor-joining (NJ) were constructed using MEGA7 software packages with nt sequences and conserved amino acid sequences of predicted RNA-dependent RNA polymerase (RdRp).The complete genome of a novel virus named Harmonia axyridis virus 1 was determined by RNA-seq and rapid amplification of cDNA ends from H. axyridis, which had a single-stranded RNA genome of 8868 nts in length and contains two putative ORFs. ORF1 encodes a polypeptide of 2182 amino acids, which contained conserved domains for 2 picornavirus-like capsid proteins and one RNA helicase. ORF2 encodes a polypeptide of 655 amino acids, which contained 1 RdRp domain. Phylogenetic analysis of whole genome nt sequences and RdRp deduced amino acid sequences suggested that the virus clustered with several unclassified Hubei picorna-like virus. To our knowledge, this is the first full annotated genome of a novel member of the unclassified group of RNA viruses, infecting H. axyridis in natural field conditions.

Baseline Sensitivity and Control Efficacy of Pyraclostrobin Against Botryosphaeria dothidea Isolates in China.

Botryosphaeria dothidea is an important fungal pathogen that causes apple ring rot, which can significantly reduce apple yield. Fungicide applications are the main control measure of apple ring rot worldwide. Pyraclostrobin is a quinone outside inhibitor (QoI) fungicide that has yet to be registered for control of B. dothidea in China. Baseline sensitivity of B. dothidea to pyraclostrobin (EC50 of mycelial growth inhibition) was assessed for 97 isolates collected in Shandong Province. The EC50 values ranged from 0.7010 to 7.1378 µg/ml with the mean value of 3.0870 µg/ml and displayed a unimodal frequency distribution. After cultured on fungicide-free PDA medium or on apples for multiple generations, the B. dothidea-resistant isolates (RST) remained resistant to pyraclostrobin, but exhibited similar virulence as the susceptible isolates (ST). Cross-resistance investigation revealed that pyraclostrobin was not cross-resistant to tebuconazole, flusilazole, carbendazim, and iprodione. Field evolution showed that pyraclostrobin at 200 and 250 g a.i./ha provided greater than 80% control efficacy against apple ring rot disease when applied as a therapeutic or preventive fungicide. The efficacy was similar to fungicides that have been registered for apple.