Functional Analysis Of Blue Light Receptor PeLreA And PeLreB In Penicillium Expansum

Penicillium expansum is an important postharvest pathogen,which mainly causes blue mold in temperate fruits such as apples,pears and grapes.In addition,the fungi also produce patulin in the fruit,resulting in potential safety risks.The growth and development of P.expansum was affected by light.In order to analyze the effects of light on the growth and development,growth phenotype and patulin accumulation of P.expansum,the functions of blue light receptor genes PeLreA and PeLreB were studied by knockout mutants and other genetic methods in this study.The results showed as below:1.The functional domains of blue photoreceptor protein PeLreA and PeLreB in P.expansum were highly homologous to those of other fungal blue photoreceptors,and both PeLreA and PeLreB had PAS domain and zinc finger domain.The results of subcellular localization showed that PeLreA and PeLreB were mainly located in the nucleus,and a small part of PeLreB was localized in the cytoplasm.2.The PeLreA and PeLreB of P.expansum were knocked out by homologous recombination and Agrobacterium tumefaciens transformation method.The knockout transformants with hygromycin resistance were identified at DNA level and RNA level.Three PeLreA gene deletion mutants and three PeLreB gene deletion mutants were obtained.3.Compared with white light and dark treatments,blue light treatment significantly inhibited the colony diameter,sporulation,spore germination rate,germ tube length,biomass and patulin production of wild type and mutant ?PeLreA and ?PeLreB,and reduced spore pathogenicity.Compared with wild type,?PeLreA and ?PeLreB significantly decreased sporulation,patulin synthesis,spore pathogenicity,biomass,spore germination rate and germ tube length under blue light treatment.4.Under the conditions of blue light,white light and dark,the expression of Pe Lae A gene in ?PeLreB was higher than that in wild type strain,but the expression level in ?PeLreA was lower than that in wild type strain.Under the condition of blue light,the expression of Pe Pat L,Pe Pat G and Pe Pat N genes in wild type was higher than that in ?PeLreA and?PeLreB,while the expression of Pe Pat E gene was the lowest in wild type.Pe Pat K gene was highly expressed in ?PeLreA and almost not expressed in ?PeLreB.5.The results of transcriptome analysis showed that the differentially expressed genes of?PeLreB and ?PeLreA were succinate dehydrogenase iron-sulfur subunit,serine/threonine-protein kinase CAK1,xylulokinase and pyruvate dehydrogenase kinase2/3/4.Under blue light condition,compared with wild type,the down-regulated genes in?PeLreA were mainly 2-dehydro-3-deoxy-D-gluconate 5-dehydrogenase,histone-lysine N-methyltransferase,C6 transcription factor and photosensitizer.The down-regulated genes in ?PeLreB were succinate dehydrogenase iron-sulfur subunit,serine/threonine-protein kinase,2-dehydro-3-deoxy-D-gluconate5-dehydrogenase and histone-lysine N-methyltransferase.It is suggested that PeLreA and PeLreB directly affect on colony diameter,spore yield,spore germination rate,germ tube length,biomass and patulin production of P.expansum.The carbohydrate metabolism,amino acid metabolism and lipid metabolism play an important role in growth and development of the fungi.