Project description:Purpose: The recent publication of the fungal mutualist R. irregularis genome facilitated transcriptomic studies. We here adress the gene regulation of R. irregularis in response to root exudates from rice wild-type and osnope1 (no perception candidate - mutant unable to host arbuscular mycorrhizal fungi) Methods: Spores of R. irregularis were treated with root exudates and collected at 1 hour, 24 hours and 7 days after addition. To monitor fungal gene regulation, control conditions were also prepared at T0, 1h, 24h and 7d. mRNA were sequenced by HiSeq Illumina. Reads were mapped on the Rhizophagus irregularis genome assembly (Gloin1 - Tisserant et al., PNAS, 2013) using CLCworkbench suite. Results: -At 1h, a set of 92 fungal genes were found up-regulated in response to wt root exudates (92), not to osnope1 root exudates, many of them being involved in cell signaling. -At 24h and 7d, numerous genes putatively involved in primary metabolism were up-regulated in response to wt root exudates, not in response to osnope1 root exudates -Several vital genes involved in cell development are repressed in response to osnope1 RE compared to wt RE. Conclusions: these results argue for a high metabolic activity induced by wt root exudates, not by osnope1 root exudates.
Project description:Magnaporthe oryzae causes rice blast, the most devastating foliar fungal disease of cultivated rice. During disease development the fungus simultaneously maintains both biotrophic and necrotrophic growth corresponding to a hemi-biotrophic life style. The ability of M. oryzae to also colonize roots and subsequently develop blast symptoms on aerial tissue has been recognized. The fungal root infection strategy and the respective host responses are currently unknown. Global temporal expression analysis suggested a purely biotrophic infection process reflected by the rapid induction of defense response-associated genes at the early stage of root invasion and subsequent repression coinciding with the onset of intracellular fungal growth. The same group of down-regulated defense genes was increasingly induced upon leaf infection by M. oryzae where symptom development occurs shortly post tissue penetration. Our molecular analysis therefore demonstrates the existence of fundamentally different tissue-specific fungal infection strategies and provides the basis for enhancing our understanding of the pathogen life style.
Project description:The rice OneArray® 60-mer, oligonucleotide microarray consists of a total of 21,179 probes covering 20,806 genes of japonica and 13,683 genes of indica. Through a validation study, total RNA isolated from rice shoots and roots were used for comparison of gene expression profiles via microarray examination. A list of significantly differentially expressed genes was generated; 438 shoot-specific genes were identified among 3,138 up-regulated genes, and 463 root-specific genes were found among 3,845 down-regulated genes. The Phalanx microarray platform is based upon the hybridization of a single labeled sample (derived from RNA), followed by one-channel detection. The intensity of the hybridization signal is used to determine target concentration. In order to validate the technical quality of each probe in our arrays, we carried out 10 independent hybridizations on samples representing two different rice tissues – root and shoot. To examine the gene expression profiles between rice root and shoot development, total RNA extracted from rice root and shoot were processed on the rice OneArray® microarray following the standard protocol using five arrays for each tissue type. Raw expression data from 10 microarrays (e.g. 5 arrays × 2 tissues) were normalized and Pearson’s correlation coefficients were calculated for the data sets of hybridization signal intensities.