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: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:Complete sequence of the obligate, root hemi-parasitic plant Striga hermonthica. We sequenced an individual from an accession of S. hermonthica seeds collected from farmer’s fields in Kibos Kenya. An individual was selected at random from parasites growing on the highly susceptible rice cultivar NERICA 7 in a controlled environment experiment.