BACKGROUND: Chemosensory proteins (CSPs) are thought to play essential roles in insect chemical communication, but their exact physiological functions remain unclear. RESULTS: In this study, we investigated the functions of the CSP2 gene in the whitefly Bemisia tabaci using protein expression and the binding affinity spectrum of CSP2 to different types of odor molecules. Moreover, the evolutionary characteristics of the CSP2 gene were studied. The data obtained using binding assay showed that the CSP2 protein can bind to a broad range of plant volatiles including the homoterpene (E)-3,8-dimethyl-1,4,7-nonatriene (DMNT) and its analogs. In addition, using a behavioral experimental approach we identified that DMNT can repel the selection and oviposition of B. tabaci. Furthermore, protein structure modeling, molecular docking analyses and a functional mutation experiment were carried out resulting in the final identification of key amino acid residue Y11, which displayed important roles in the binding of CSP2 to DMNT. The results also showed that Y11 is located in the pocket region where CSP2 has a pi-alkyl interaction with DMNT. Meanwhile, comparative and evolutionary analyses indicated that CSP2 shared a high sequence similarity with CSPs of other insect family members such as Sternorrhyncha and Auchenorrhyncha including aphids, whiteflies and planthoppers. CONCLUSION: These results suggested that CSP2 likely contributes to mediating responses of B. tabaci to plant volatiles, which may play a pivotal role in its feeding and oviposition preferences. Moreover, these findings could provide key information for exploring efficiency monitoring and integrated pest management strategies of B. tabaci.

Mycoplasma capricolum subsp. Capricolum (Mcc) is an important member of the Mycoplasma mycoides cluster (Mm cluster) and causes caprine contagious agalactia. Mcc can infect goats of all age groups, especially pregnant ewes and kids. It can cause the abortion in pregnant ewes and the death of goat kids, leading to enormous losses in the goat breeding industry. To date, the prevalence of epidemic Mcc strains on Hainan Island, China, remains unclear. This study aimed to isolate and identify Mcc strains endemic to Hainan Island, China. Genome sequencing and comparative genomic analysis were performed to reveal the molecular characteristics and evolutionary relationships of the isolated strain. Mcc HN-B was isolated and identified in Hainan Island, China. The Mcc HN-B genome consists of a 1,117,925 bp circular chromosome with a 23.79% G + C content. It contains 912 encoding genes, 3 gene islands, and 14 potential virulence genes. The core genome with the features of the Mm cluster and the specific genes of Mcc HN-B were identified by comparative genomic analysis. These results revealed the evolutionary relationship between Mcc HN-B and other members of the Mm cluster. Our findings provide a reference for further studies on the pathogenic mechanism and local vaccine development of Mcc.

Mycoplasma mycoides subspecies capri (Mmc) is one of the six Mycoplasma mycoides cluster (Mm cluster) members, which can cause “MAKePS” (Mastitis, Arthritis, Keratoconjunctivitis, Pneumonia, Septicemia) syndrome in ruminants. These symptoms can occur alone or together in individuals or flocks of goats. However, little is known about the epidemic Mmc strains in Hainan Island, China. We aimed to isolate the endemic Mmc strains in Hainan Island and reveal their molecular characteristics by genomic sequencing and comparative genomics to mitigate the impact of Mmc on local ruminant farming. Here, the Mmc HN-A strain was isolated and identified for the first time in Hainan Island, China. The genome of Mmc HN-A was sequenced. It contains a 1,084,691 bp-long circular chromosome and 848 coding genes. The genomic analysis of Mmc HN-A revealed 16 virulence factors, 2 gene islands, and a bacterial type IV secretion system protein VirD4. Comparative genomics showed that the core genome of the five Mycoplasma mycoides contained 611 genes that could be exploited to develop drugs and endemic vaccines. Additionally, 36 specific genes were included in the Mmc HN-A genome, which could provide the possibility for the further control and prevention of the Mmc effects on local ruminants and enrich the information on Mmc strains.