Characteristics And Functional Analysis Of Homeobox Gene MaH1 In Metarhizium Acridum

Entomopathogenic fungi infect the insects by conidia.Therefore,the quantity and the quality of conidiation are two important parameters in the application of biological pesticide.Most filamentous fungi have two conidiation patterns: normal and microcycle conidiation.In the filamentous fungi,there is relatively much more research on normal conidiation,but less research on micricycle conidiation.Metarhizium acridum can make a pattern shift from normal to microcycle conidiation under different nutrients condition.Microcycle conidiation can produce more conidia in a shorter time compared with normal conidiation.Moreover,the conidia formed by microcycle conidiation are more uniform in size compared with those formed by normal conidiation.Therefore,the research on the mechanism of microcycle conidiation can provide theoretical basis and new technology for modification to insecticidal fungi.In this study,the total cDNA length of MaH1 was 1863 bp,which encoded 620 amino acids and contained three exons.The conserved domain of MaH1 was 180 bp,and contained the structure of ‘Helix-Turn-Helix' by bioinformatic analysis.The expression level of MaH1 was highest when it began to produce conidia.We constructed ?MaH1 strain and CP strain,and studied on their function.It was found that the conidia germination and the size of colony show differentiation between the mutation strain and the wild-type strain.The conidiation of Metarhizium acridum was convert normal conidiation into microcycle conidiation on 1/4 SDAY medium.After 14 h,the mutation strain and the wild-type strain began to show differentiation with conidiation on 1/4 SDAY medium.The conidiation of the mutation strain earlier 2 hours than the wild-type strain.The number of conidiation and biomass in the mutation strain was increased by contrast with the wild-type strain.After the observation on hyphae and conidia,it was found that MaH1 affected the size of hyphae cell and changed the conidial form.Besides,MaH1 has no effect on the resistance and virulence of Metarhizium acridum.According to the digital expression profiling(DGE)analysis,85 differentially expressed genes were found in the conidiation process after MaH1 was deleted,including 55(64.7%)known genes,30(35.3%)unknown genes,19 of which were up-regulated,66 genes were down-regulated.These mainly functional of differentially expressed genes were related to conidiation,cell membrane,metabolism and transport.The 27 genes of 55 known differential expression genes were found to be associated with mycelial growth,cell growth,germination and conidiation,and the rest part of the genes were associated with metabolism and stress resistance function.These results indicate that MaH1 further regulates the transformation of conidiation patterns by change the expression of hyphae,cell growth and conidiation related genes.In addition,some important signaling pathway also directly or indirectly cause an effect on the transformation of conidiation patterns.