Project description:Using rice cultivars Nipponbare, which exhibits resistance to Striga hermonthica (a root parasitic plant that causes devastating loss of yield), and IAC165, which is susceptible, we aim to identify suites of genes underlying susceptibility and resistance to S. hermonthica by profiling changes in gene expression using rice whole genome microarrays. In addition to a functional categorisation of changes in gene expression, genes that were significantly differentially regulated within regions predicted to contain Nipponbare quantitative trait loci for resistance were identified. Experiment Overall Design: Root tissue was harvested from two cultivars of rice that had been infected with Striga hermonthica (or from uninfected control tissue). Three timepoints were used (2, 4 and 11 days after infection or mock-inoculation) using two replicate chips per treatment/timepoint.
Project description:Using rice cultivars Nipponbare, which exhibits resistance to Striga hermonthica (a root parasitic plant that causes devastating loss of yield), and IAC165, which is susceptible, we aim to identify suites of genes underlying susceptibility and resistance to S. hermonthica by profiling changes in gene expression using rice whole genome microarrays. In addition to a functional categorisation of changes in gene expression, genes that were significantly differentially regulated within regions predicted to contain Nipponbare quantitative trait loci for resistance were identified. Keywords: Infected material vs. comparable control tissue, time course
Project description:The purpose of this study was to annotate microRNAs in the parasitic plant Striga hermonthica and investigate any haustorial specific expression of novel microRNAs.
Project description:Variation in strigolactone composition in sorghum root exudates underlies its resistance to parasitic weed, Striga hermonthica. Root exudates of the Striga susceptible variety Shanqui Red (SQR) contain primarily 5-deoxystrigol, which has a high efficiency of inducing Striga germination. SRN39 roots primarily exude orobanchol, leading to reduced Striga germination and making this variety resistant to Striga. This structural diversity in exuded strigolactones is determined by the polymorphism in the LGS1 (LOW GERMINATION STIMULANT 1) locus. Yet, the effects of the lgs1 mutation as well as the consequences of the vast genetic diversity between SQR and SRN39 have not been addressed in terms of growth and development. In response to this knowledge gap, we demonstrate additional consequences of LGS1 loss-of-function by phenotypic and molecular characterization. A suite of genes related to metabolism was differentially expressed between SQR and SRN39. Increased levels of gibberellin precursors in SRN39 were accompanied with its slower growth rate and developmental delay and we observed an overall increased SRN39 biomass. The slow-down in growth and differences in transcriptome profiles of SRN39 were strongly associated with plant age. Additionally, analyses of multiple LGS1 loss-of-function genotypes indicated that strigolactone stereochemistry influences root system architecture. To summarize, we demonstrated that the consequences of lgs1 mutation reach further than the changes in strigolactone profiles in root exudates and translates to alteration in growth and development.
Project description:Sorghum bicolor is one of the most important cereal crops in the world, predominantly grown in sub‑Saharan Africa by smallholder farmers. Despite its outstanding resilience to abiotic stresses, approximately 20% of sorghum yield is annually lost on the African continent due to infestation with the parasitic weed Striga hermonthica. Existing Striga management strategies to decrease Striga infestation often show low efficiency and are not easily integrated into current agricultural practices. Microbial-based solutions may prove an effective, low-cost mode for reducing Striga parasitism in sub-Saharan Africa. Here, we demonstrate that the microbiome component of a field soil suppresses Striga infection of sorghum. Potential mechanisms underlying the soil microbiome’s influence on the host plant include root endodermal suberization and aerenchyma formation. Moreover, we observed a depletion of haustorium inducing factors, compounds essential for Striga to establish the host-parasite association, in root exudates collected from sorghum grown in the presence of the soil microbiome as compared to sterile conditions. We further identified individual microbial taxa associated with reduced Striga infection via changes in root cellular anatomy and differentiation as well as in exudate composition. Our study identifies a suite of traits that can be harnessed by individual microbial isolates or their consortia to induce Striga resistance. Combining microbes that elicit Striga resistance directly (affecting the parasite) via repression of haustorium formation with those that act indirectly (affecting the host), by reducing of Striga penetration through root tissue, can broaden the effectiveness of microbe-induced protection from Striga.
Project description:To understand pathogenicity and in planta transcriptional reprogramming, expression profiles of U. virens during infection of the resistant and susceptible cultivars were analyzed using RNA-seq data. Predicted host-pathogen interaction database (PHI-base) genes that are probably involved in host-pathogen interactions were found to be significantly enriched in fungal differential expressed genes from both rice genotypes, indicating their potential roles in pathogenicity of U.virens. Our results also indicate that genes for secreted proteins and secondary metabolism are highly enriched in the transcriptome during early infection of susceptible cultivars. GO enrichment analysis suggest that bilogical processes required for successful infection of U. virens are greatly suppressed in the resistant cultivars.
Project description:TITLE: Transcriptional profiling of Rgene-mediated responses in rice PROJECT DESCRIPTION: The dominant gene Xa7 and the recessive gene xa5 of rice confer resistance to several races of the bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo). To reveal the modes of action and the defense responses these genes initiate, we decided to obtain the global transcriptional profiles of the rice cultivars IRBB7, IRBB5 (which harbor Xa7 and xa5, respectively) and IR24 undergoing early infection by the Xoo Race 2 strain PXO86. Both IRBB7 and IRBB5 are resistant to PXO86 (which carry the corresponding avirulence genes avrXa7 and avrxa5), whereas IR24 is susceptible. We inoculated by vacuum infiltration the three rice cultivars ten days after seed germination (or 2 weeks after sowing) and collected inoculated tissue at 5 different timepoints within the first day after inoculation. The transcriptional profiles obtained will provide valuable insight into the similarities and differences between incompatible interactions mediated by a dominant and a recessive Rgene, in comparison to a compatible interaction. ****[PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, David O Nino-Liu. The equivalent experiment is OS4 at PLEXdb.]
Project description:Background. Cowpea, Vigna unguiculata L. Walp., is one of the most important food and forage legumes in the semi-arid tropics. While most cowpea accessions are susceptible to the root parasitic weed Striga gesnerioides, several cultivars have been identified that show race-specific resistance. Cowpea cultivar B301 contains the RSG3-301 gene for resistance to S. gesnerioides race SG3, but is susceptible to race SG4z. When challenged by SG3, roots of cultivar B301 develop a strong resistance response characterized by a hypersensitive reaction and cell death at the site of parasite attachment. In contrast, no visible response occurs in B301 roots parasitized by SG4z. Results. Gene expression in the roots of the cowpea cultivar B301 during compatible (susceptible) and incompatible (resistant) interactions with S. gesnerioides races SG4z and SG3, respectively, were investigated at 6 and 13 days post-inoculation (dpi), in the early and late stages of the resistance response using a Nimblegen custom design cowpea microarray. A total of 111 genes were differentially expressed in B301 roots at 6 dpi; this number increased to 2102 genes at 13 dpi. At 13 dpi, a total of 1944 genes were differentially expressed during compatible (susceptible) interactions of B301 with SG4z . Genes and pathways involved in signal transduction, programmed cell death and apoptosis, and defense response to biotic and abiotic stress were differentially expressed in the early resistance response; at the later time point, enrichment was primarily for defense-related gene expression, and genes encoding components of lignifications and secondary wall formation. In compatible interactions (B301 M-bM-^@M-^S SG4z), multiple defense pathways were repressed, including those involved in lignin biosynthesis and secondary cell wall modifications, while cellular transport processes for nitrogen and sulfur were increased. Conclusion. Distinct changes in global gene expression profiles occur in host roots following successful and unsuccessful attempted parasitism by Striga. Induction of specific defense related genes and pathways defines components of a unique resistance mechanism. Some genes and pathways up-regulated in the host resistance response to SG3 are repressed in the susceptible interactions, suggesting that the parasite is targeting specific components of the hostM-bM-^@M-^Ys defense. These results add to our understanding of plant-parasite interactions and the evolution of resistance to parasitic weeds. A Nimblegen custom design cowpea microarray investigating gene expression in the roots of the cowpea cultivar B301 during compatible (susceptible) and incompatible (resistant) interactions with S. gesnerioides races SG4z and SG3, respectively, at 6 and 13 days post-inoculation (dpi), in the early and late stages of the resistance response.