| Bemisia tabaci,a worldwide invasive pest,which seriously destroyed the agricultural system due to its wide distribution and feeding diversity.In China,the MED and Asia?1 cryptic species are significantly different in the range of distribution.It is speculated that the difference of temperature adaptability between the two cryptic species is one of the most important reasons for the difference of distribution range.Epigenetic mechanisms play a significant role in the process of invasive organisms rapidly adapting to new environments,reproducing rapidly and expanding their range.Histone modification is an important epigenetic mechanism that plays an important role in the response of organisms to temperature stress.Therefore,based on the ecological phenomenon that the geographical distribution of two cryptomycete species is significantly different and from an epigenetic perspective,we studied the difference temperature tolerance of two cryptic species under different stress temperature treatments.Based on this,the cDNA of MOF and GCN5 of two B.tabaci cryptic species were cloned using PCR;the relative expression of MOF and GCN5 were tested by qPCR to anaylse the difference between two species;and the temperature tolerance of MOF and GCN5 in two B.tabaci cryptic species were verified using RNAi.The main results and conclusions are as follows,1.The full cDNA sequences of MOF and GCN5 in B.tabaci MED and Asia?1 cryptic species were cloned.(1)the ORF of MOF in two B.tabaci cryptic species are both 1332 bp,encoding 443 a mino acids,and named as MEDBtMOF and Asia?1BtMOF respectively;(2)and the ORF of GCN5 in two B.tabaci cryptic species are both 2472 bp,encoding 823 a mino acids,and named as MEDBt GCN5 and Asia?1BtGCN5 respectively.2.The sequence analysis and phylogenetic analysis of MOF and GCN5 gene were completed.The results showed that the nucleotide sequence of MOF and GCN5 has 3 and 15 different basepairs respectively,however,the the a mino acid sequence is exactly the same.The phylogenetic tree showed that the insect MOF and GCN5 are both relatively conservative in evolution.And homologue insects can be clustered on the same evolutionary branch.3.The expression pattern of MOF and GCN5 gene have been detected under gradient temperature stress.(1)comparing with the control,there is no significant differences in general expression trend in Asia?1 cryptic species under short-term temperature stress,but in MED cryptic species,the trend is on the rise;(2)comparing with the control,there is no significant differences in general expression trend in both cryptic species under short-term temperature stress.4.The internal functional identification of MOF and GCN5 are completed.The expression of the target gene can be effectively suppressed after feeding dsRNA.The results after RNAi showed that(1)the heat resistance and cold tolerance in the two B.tabaci cryptic species can be significantly decreased after the reduction of the expression of MOF,but it is different in two species;(2)the significant difference of cold tolerance was showed in the two B.tabaci cryptic species after the reduction of the expression of GCN5,but no significant difference in heat resistance.Based on the above results,it is concluded that MOF and GCN5 play an important role in the response to the temperature stress in B.tabaci.Besides,the mechanisms of these two gene in the the process of temperature adaptation in two cryptic species is different.It is speculated that MOF plays an important role in the process of population establishment and settlement selection of two cryptic species of Bemisia tabaci.The results lay a foundation for the identification of epigenetic mechanisms of temperature tolerance differences in two B.tabaci cryptic species,and provide a new perspective for future research on the temperature adaptability of invasive insects.It is expected to provide a new theoretical basis for the formulation of sustainable control strategies for B.tabaci. |
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