ABSTRACT
⢠The arbuscular mycorrhizal symbiosis is arguably the most ecologically important eukaryotic symbiosis, yet it is poorly understood at the molecular level. To provide novel insights into the molecular basis of symbiosis-associated traits, we report the first genome-wide analysis of the transcriptome from Glomus intraradices DAOM 197198. ⢠We generated a set of 25,906 nonredundant virtual transcripts (NRVTs) transcribed in germinated spores, extraradical mycelium and symbiotic roots using Sanger and 454 sequencing. NRVTs were used to construct an oligoarray for investigating gene expression. ⢠We identified transcripts coding for the meiotic recombination machinery, as well as meiosis-specific proteins, suggesting that the lack of a known sexual cycle in G. intraradices is not a result of major deletions of genes essential for sexual reproduction and meiosis. Induced expression of genes encoding membrane transporters and small secreted proteins in intraradical mycelium, together with the lack of expression of hydrolytic enzymes acting on plant cell wall polysaccharides, are all features of G. intraradices that are shared with ectomycorrhizal symbionts and obligate biotrophic pathogens. ⢠Our results illuminate the genetic basis of symbiosis-related traits of the most ancient lineage of plant biotrophs, advancing future research on these agriculturally and ecologically important symbionts.
Subject(s)
Glomeromycota/genetics , Mycorrhizae/genetics , Symbiosis/genetics , Transcriptome/genetics , Base Sequence , Colony Count, Microbial , Fungal Proteins/chemistry , Fungal Proteins/genetics , Fungal Proteins/metabolism , Gene Expression Regulation, Fungal , Gene Library , Genes, Fungal/genetics , Glomeromycota/growth & development , Meiosis/genetics , Mycelium/genetics , Mycorrhizae/growth & development , Plants/microbiology , Polymorphism, Single Nucleotide/genetics , Protein Structure, Tertiary , RNA, Messenger/genetics , RNA, Messenger/metabolism , Up-Regulation/geneticsABSTRACT
Beet western yellows virus relies on the aphid M. persicae for its transmission in a persistent and circulative mode. To be transmitted, the virus must cross the midgut and the accessory salivary gland epithelial barriers by a transcytosis mechanism where vector receptors interact with virions. The aphid and the peptidic viral determinants implicated in this interaction mechanism have been studied. In this paper, we report that the coat and the readthrough proteins that constitute the capsid of this virus are glycosylated. Modification of the glucidic core of these structural viral proteins by oxidation with sodium metaperiodate or deglycosylation with N-glycosidase F or alpha-D-galactosidase abrogates the aphid transmission of the virus. Aphid transmission could also be inhibited by lectins directed against alpha-D-galactose when aphids were allowed to acquire virus on artificial membranes. These results suggest that the glucidic cores of the capsid proteins of beet western yellows virus contain alpha-D-galactose residues that are implicated in virus-aphid interaction and promote aphid transmission of the virus.
