Development Regulation By VeA In Marine-derived Aspergillus Glaucus

Aspergillus glaucus HB1-19 is a marine-derived filamentous fungus isolated from the mangroves in South China Sea.Compared to Aspergillus nidulans,a terricolous model mold,it can tolerate high salt and has some unique characteristics.In our previous study,it showed that salt stress inhibited sexual development but promoted asexual development of A.glaucus HB1-19.Based on the molecular mechanism by which A.nidulans responds to the environmental stress(e.g.illumination),it is speculated that morphological development of A.glaucus is also regulated by VeA complex,which consists of VeA,FphA,LreA and LreB.Genome walking was first performed to clone the flanking gene sequences of AgveA,AgfphA,AglreA and AglreB.The introns and extrons of these genes were then confirmed by reverse transcription.Our results showed that different levels of salt stress resulted in different phenotypes of A.glaucus.In NaCl solution(isotonic to artificial sea water),the asexual development was effectively improved and the fungus produced a large number of conidiospores.In artificial sea water,the fungus produced a lot of conidiospores and a small number of cleistothecia.In deionized water,the sexual development was effectively improved and the fungus produced a large number of cleistothecia.The results of qRT-PCR showed that the transcription of AgveA was obviously influenced by salt stress,while AgfphA,AglreA and AglreB were not.The salt stress affected the transcription of AgveA and might also have a role in interaction among proteins of VeA complex.Due to the central role of VeA in complex and the fact that transcription of AgveA was obviously influenced by salt stress,a ?AgveA strain was constructed to further study the functions of VeA in marine fungus A.glaucus HB1-19.The mycelial morphology,colony morphology,mycelial growth rate and their development were evaluated.The mycelial morphology changed little.There were defects in the edge of colonies.Mycelial growth rate rose in the late stages of development.And their developmental pattern also changed.The deletion of AgveA resulted in the blockage in production of cleistothecia under high salt stress,while it produced a lot of conidiosprores and simultaneously few cleistothecia under low salt stress.