Background: Xanthomonas oryzae pv. oryzae (Xoo) causes rice leaf blight (BLB) and poses a major threat to global rice production. In rice production, tetramycin agents provide good control of rice leaf blight, while the standardization of the reference genes of Xoo under tetramycin stress has not been reported. The aim of this study was to identify the most stable reference genes for quantitative PCR analysis of Xoo under tetramycin stress. Methods: Six candidate reference genes, gyrB (RNA polymerase β gene), GADPH (glyceraldehyde-3-phosphate dehydrogenase gene), recA (recombinase A gene), gyrA (citrate synthase encoding gene), dnaK (molecular chaperone protein gene), and 16S rRNA (16S ribosomal RNA gene) were selected and their expression stability was assessed under tetramycin stress conditions using real-time quantitative PCR (qRT-PCR). GeNorm, NormFinder, BestKeeper and RefFinder were used to assess the expression stability, the relative expression values of the eight genes involved QS (Quorum sensing) pathway under tetramycin stress were used to validate by the rpf (regulation of pathogenic factors) gene family. Results: 16S rRNA expression was most stable under tetracycline stress, whereas GADPH was the least. The rpf gene family showed a highly stable expression level, confirming the reliability of 16S r RNA as a reference gene in the study of Xoo under tetramycin stress. Conclusions: 16S rRNA was identified as the best reference gene for Xoo gene expression analysis under tetramycin stress. It provides a reliable support for the molecular research on the control strategy of rice BLB.

Vespa soror, is an important resource insect that is widely distributed in China. However, there have been few reports on the genetic diversity of this species so far. We based our study on Cytochrome c Oxidase Subunit I (COI) gene as a molecular marker, to estimate the genetic diversity of V. soror. The length of the COI gene is 614 base pairs (bp), and a total of 26 haplotypes were obtained. Among these haplotypes, Hap_3 and Hap_13 are the dominant haplotypes. Overall, V. soror exhibits high genetic diversity, with a haplotype diversity (Hd) of 0.941 ± 0.010 and a nucleotide diversity (Pi) of 0.01068 ± 0.00079. Significant genetic differentiation has occurred among populations, with pairwise Fixation Index (Fst) values greater than 0.25 accounting for over two-thirds of all comparisons. The overall FST value was 0.47872. Despite fluctuations in the degree of genetic differentiation among different populations (−0.076 to 1.00), the overall level of genetic differentiation remained within a relatively high range. For most populations, the Tajima’s D and Fu’s Fs test results were positive, and both were non-significant (p > 0.10). AMOVA attributed 15.82%, 36.37%, and 47.81% of total variation to among-group, among-population within-group, and within-population variation, respectively. Overall, it exhibits high genetic diversity, significant genetic differentiation.