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Background:Blattella germanica is a widespread urban invader insect that can spread numerous types of human pathogens, including bacteria, fungi, and protozoa. Despite the medical significance of B. germanica, the genetic diversity of this species has not been investigated across its wide geographical distribution in China.Objective:In this study, the genetic variation of B. germanica was evaluated in central China.Methods:Fragments of the mitochondrial cytochrome c oxidase subunit I (COI) gene and the 16S rRNA gene were amplified in 36 B. germanica isolates from 7 regions. The sequence data for COI and 16S rRNA genes were analyzed using bioinformatics methods.Results:In total, 13 haplotypes were found among the concatenated sequences. Each sampled population, and the total population, had high haplotype diversity (Hd) that was accompanied by low nucleotide diversity (Pi). Molecular genetic variation analysis indicated that 84.33% of the genetic variation derived from intra-region sequences. Phylogenetic analysis indicated that the B. germanica isolates from central China should be classified as a single population. Demographic analysis rejected the hypothesis of sudden population expansion of the B. germanica population.Conclusion:The 36 isolates of B. germanica sampled in this study had high genetic variation and belonged to the same species. They should be classified as a single population. The mismatch distribution analysis and BSP analysis did not support a demographic population expansion of the B. germanica population, which provided useful knowledge for monitoring changes in parasite populations for future control strategies.

Hydrogen gas (H2) has been recently regarded as a novel gaseous signaling molecule that performs multiple functional roles in plant. Here, we demonstrate that hydrogen rich water (HRW)-an experimentally tractable reagent to assess the effects of the H2 significantly delays wheat aleurone layer programmed cell death (PCD) induced by gibberellic acid (GA). Endogenous H2 production exhibited lower level in aleurone layers under GA treatment, whereas the H2 production was apparently increased under abscisic acid (ABA) treatment. HRW not only increased H2 production but also delayed GA-induced PCD. We further observed that application of HRW substantially prevented the increases of hydrogen peroxide (H2O2) and superoxide anion radical (O2.-) triggered by GA. HRW also directly react with hydroxyl radical (·OH) to delay GA-induced PCD. Quantitative real-time PCR (qRT-PCR) and biochemical assays showed that HRW induced the transcripts and enzymatic activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) that metabolize reactive oxygen species (ROS); these increases coincided with the observed changes in O2.-, H2O2 and ·OH accumulation upon GA treatment. Our study therefore suggests that HRW-triggered alleviation of wheat aleurone layer PCD induced by GA results from a combination of H2-mediated decreases of ROS levels, including O2.-, H2O2, and ·OH.

Effect of chitosan (CS) enriched with salicylic acid (SA) treatment on physicochemical quality enhancement of Chinese kiwi fruit (Actinidia chinensis Planch) was evaluated during storage at room temperature for 14 days. Preservative treatment samples were dipped by CS, SA, and their combination (CS + SA), compared with the control treated by distilled water. Changes in texture, weight loss, surface colour, pH, vitamin C, soluble solids content (SSC), and microbiology were synchronously examined. Results demonstrated that chitosan with salicylic acid presented more effective preservative effect than sole chitosan or salicylic acid treatment. This optimal treatment significantly maintained texture and colour, inhibited moisture loss and acidity change, and delayed the decomposition of vitamin C and soluble solids. The optimal treatment efficiently maintained texture and surface colour, inhibited weight loss percentage (2.60 %) and acidity change, and delayed the decomposition of vitamin C (maximal content 97.93 mg/kg) and soluble solids. Therefore, CS enriched with SA coating provides an efficient alternative for physicochemical quality enhancement of Chinese kiwi fruits.