The Regulatory Mechanism Of SelT And TG Genes On Active Immunization Against Metarhizium Anisopliae In The Termite Reticulitermes Chinensis

Social insects such as termites can use active immunization strategies similar to“the inoculation of humans”to defend against pathogenic fungal infections,but the molecular regulatory mechanism of active immunization of termites is still not fully understood.During the active immunization of termite Reticulitermes chinensis Snyder,1 d after the nestmates of fungus-contaminated termites contacted to fungus-contaminated termites,the expression of selenoprotein T?Sel T?gene was significantly decreased?P<0.05?,suggesting that Sel T gene may be related to active immunization of termites.Transglutaminase?TG?as an insect immune protein can promote blood coagulation formation and may play an important role in the immune process of termites against pathogenic fungi.In view of this,this paper used the termite R.chinensis and the pathogenic fungus Metarhizium anisopliae?Metchnikoff?Sorokin as experimental materials,and established a"host-pathogen"system?fungus-contaminated termite and nestmates were cultured together?to carry out a study of the regulation mechanism of Sel T and TG genes on active immunization against M.anisopliae in the termite R.chinensis.The main results are as follows:?1?Inhibiting Sel T gene expression broke the active immunization of R.chinensis.First,the fragment of the Sel T gene?572bp?of R.chinensis was cloned,and ds Sel T was synthesized successfully.The expression of Sel T gene was significantly reduced,3d after ds Sel T was injected into the termites?P<0.01?.After Sel T was significantly knocked down,there were no significant changes in the grooming frequency and cumulative duration of grooming of the nestmates of fungus-contaminated termites,but there were significantly decreased antifungal activity?P<0.05?and survival?P<0.05?in the nestmates of fungus-contaminated termites,indicating that knockdown of Sel T gene broke the active immunization of R.chinensis against M.anisopliae.After interfering with the Sel T gene,the expressions of immune genes TG and transferrin?Tsf?were significantly increased in the nestmates of fungus-contaminated termites?P<0.05?,suggesting that the two immune genes may be involved in the process of Sel T-regulating active immunization of R.chinensis.After silencing Sel T gene,the expressions of two insulin synthesis-related genes protein kinase A?PKA?and calcium/calmodulin-dependent protein kinase II?CAMK2?,three insulin signaling pathway-related genes RAC serine/threonine-protein kinase?AKT?,insulin-like peptide2?ILP2?and insulin receptor?INR?,and two calcium signaling pathway-related genes P-type Ca²⁺transporter type 2A?SERCA?and ryanodine receptor 1?RYR?were increased significantly?P<0.05?,indicating that the insulin signal and calcium signal pathway may be related to the Sel T-regulating active immunization of R.chinensis.?2?Inhibiting TG gene expression broke the active immunization of R.chinensis.First,the TG gene fragment?516 bp?of R.chinensis was cloned,and ds TG was synthesized successfully.After 3 d of ds TG injection,the TG gene expression was significantly reduced?P<0.01?.After TG was significantly knocked down,the nestmates of fungus-contaminated termites significantly decreased grooming frequency?P<0.05?and cumulative duration of grooming?P<0.05?.Also,the antifungul activity?P<0.05?and survival?P<0.05?were also significantly reduced in the TG-silenced nestmates of fungus-contaminated termites,which indicates that knockdown of TG gene broke the active immunization of R.chinensis against M.anisopliae.At the same time,after silencing the TG gene,the expression of Sel T gene was significantly up-regulated in the nestmates of fungus-contaminated termites?P<0.05?,which further showed that TG and Sel T genes were inter-related and together participated in the regulation of active immunization in the termite R.chinensis.In summary,the downregulated expressions of both Sel T and TG genes can break the active immunization of R.chinensis against M.anisopliae.Although both Sel T and TG genes participate in the regulation of active immunization of termites,they can separately play a regulatory role in the active immunization of termites,each of which can serve as a potential target gene for breaking active immunization of termites and provide the possibility for developing more efficient biocontrol agents against termites.