Functional Analysis Of MaCreA In Conidial Patterns In Metarhizium Acridum

The normal conidiation and microcycle conidiation are two patterns of asexual conidiation in filamentous fungi.For a proper vegetative growth,asexual conidia are produced by the top or sides of the hyphae in a subsequent budding-like process in normal conidiation,while microcycle conidiation occurs when fungi are subjected to unfavorable environmental conditions.As a survival mechanism,the microcycle conidiation no longer undergoes a hyphae extension stage,conidia directly generate from germ tubes or conidial cells.Faster conidiation,higher conidial yield,even higher resistance to stress conditions and more uniform physiological level of conidia are features of microcycle conidia compared to normal conidia.Based on the advantages of this microcycle conidia,studying and using this conidial pattern will make a good sense of production practice.Metarhizium acridum,as a variant of Metarhizium anisopliae,is a specific pathogenic fungus to locust and a model organism of entomopathogenic fungus.In the previous study in our laboratory,it was found that microcycle conidiation of M.acridun can be induced by changing the nutrient conditions,indicating that there are two patterns of conidiation in M.acridum.A CreA homologous gene was found in the M.acridum genomic database,named MaCreA,whose ORF was 1131 bp with 376 amino acids.In our previous study,conidial yield of ?MaCreA declined sharply.In this research,the ?MaCreA strains colony was fluffy and white,with strong mycelium,and the conidiation was obviously delayed.Microcycle conidiation was not seen when changing nutrient conditions in the knockout strains.The sequencing of RNA in ?MaCreA and wild type strains in different medias at conidiation results showed that conidial process involved GO functions such as metabolic activities,catalytic activity,binding activity and transport activity in the molecular level,and also related to plasma membrane and cell components.Both pathways of conidiation were enriched to peroxisome,an organelle involved in conidiation.Meanwhile,we noticed that the GO Function enrichment and pathways enrichment of the differential expression genes in microcycle conidiation were contained in the normal conidiation's,implying that life activities in microcycle conidiation wree more single.Further,a up-regulated gene on SYA media was found,and seven potential binding sites of CREA was found on promoter of this up-regulated gene.Blast results showed that this gene was late sexual development protein(LSDA),after deletion of this gene,the conidiation of M.acridum was significantly delayed and the microcycle conidiation was lost,suggesting that this gene is involved in the microcycle conidiation.