Arbuscular mycorrhizal fungi(AMF) can colonize and form associations with the roots of Amorpha fruticosa L.(desert false indigo). Various genes are induced during the symbiotic process. In this study, de novo transcriptome sequencing using RNA-seq was conducted for the first time for a comprehensive analysis of AMF-A. fruticosa symbionts at the transcript level. We obtained 12 G of raw data from illumina sequencing and recovered 115,786 unigenes with an average length of547 bp, among them 41,848 of significance. A total of2460 diffexpression genes were identified, including 1579 down-regulated and 881 up-regulated genes. A threshold for false discovery rate of \ 0.001 and fold change of [ 1 determined significant differences in gene expression.Using these criteria, we screened 285 significant differentially expressed genes, of which 82 were up-regulated and203 down-regulated. The 82 up-regulated genes were classified according to their functions and assigned into seven categories: stress and defense, metabolism, signaling transduction, protein folding and degradation, energy,protein synthesis, and transcription. The 203 down-regulated genes were screened according to fold change [ 2,and 50 highly significant down-regulated genes were obtained related to stress and defense. The results of this study will provide a useful foundation for further investigation on the metabolic characteristics and molecular mechanisms of AMF associations with leguminous woody shrubs.
Arbuscular mycorrhiza （AM） formed between plant roots and fungi is one of the most widespread symbiotic associations in nature. To understand the molecular mechanisms of AM formation, we profiled 30 symbiosis-related genes expressed in Amorpha fruticosa roots colonized by Glomus mosseae and in non-mycorrhizal roots at different stages using differential-display RT-PCR （DDRT-PCR）. The expressed genes were confirmed by reverse Northern blotting. Eleven fragments were sequenced and putatively identified by homologous alignment. Of the eleven AM-related genes, five were obtained at the early-stage of plant-fungus interaction and six at the later stage. Three expressed se-quence tag （ESTs） sequences were found to originate from the fungi and eight from the host plant by use of PCR evaluation of gDNA of both plant and fungi. The target genes included an ATP-binding cassette sub-family transporter gene, a transposon-insertion display band, and a photosynthesis-related gene. The results provided information on the molecular mechanisms underlying the development of mycorrhizal sym-biosis between woody plants and AM fungi.
