Molecular characterisation and expression analysis of developmentally regulated genes in Agaricus bisporus

Abstract

Analysis of cDNA transcripts, PCR based methods and genomic library screening have been used to clone and characterise developmentally regulated genes in the cultivated white button mushroom Agaricus bisporus. Up-regulated genes identified during the rapid expansion phase of the sporophore include sugar transporter gene sut1, putative riboflavin-aldehyde-formingenzyme gene (raf) and three novel morphogenes mag2-mag4. Further, a hexose transporter gene sut2 and lectin genes abl1 and abl2, among others have been cloned from A. bisporus using PCR based strategies. Northern analysis indicated their up-regulation during sporophore differentiation and development. Sugar transporter gene sut1 transcripts increased abundantly during sporophore development and although sut1 showed varying levels of homology to other sugar transporters, its substrate preference could not be identified based on homology. Interestingly, analysis of basidiomycete genome sequences revealed the presence of a putative sut1 homolog in the white rot fungus Phanerocheate chrysosporium. On the other hand, Ab sut2 showed strong homology to fungal glucose/hexose transporters and its homologs also appear to be present in A. bitorquis and Coprinus cinereus suggesting a generic role. Analysis of the genomic cosmid clones revealed that the lectin genes abl1 and abl2 are present in close proximity to each other and further characterisation is on-going.