Overcoming chemical betrayal: plant defensive signalling against pathogens

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• Dr Josiah Mutuku, BioSciences East and Central Africa, Nairobi
• Friday 20 November 2015, 14:00-15:00
• Tom ap Rees, Department of Plant Sciences.

If you have a question about this talk, please contact jpc1005.

The root hemiparasite witchweed (Striga spp.) is a devastating agricultural pest that causes losses of up to 1 billion USD annually in sub-Saharan Africa. Development of resistant crops is one of the cost-effective ways to address this problem. However, the molecular mechanisms underlying resistance are not well understood. To understand molecular events upon Striga infection, we conducted genome scale RNA -Seq expression analysis using Striga-infected rice roots. We found that transcripts grouped under the gene ontology term “defense response” were significantly enriched in upregulated differentially expressed (DE) genes. In particular, we found that both jasmonic acid (JA) and salicylic acid (SA) pathways were induced, but the induction of the JA pathway preceded that of the SA. Foliar application of JA resulted in higher resistance. The hebiba mutant plants, which lack the JA biosynthesis gene AOC , exhibited severe Striga susceptibility. The resistant phenotype was recovered by application of JA. By contrast, the SA-deficient NahG rice plants were resistant against Striga, indicating endogenous SA is not required for resistance. However, knocking down WRKY45 , a regulator of the SA/BTH pathway resulted in enhanced susceptibility. Interestingly, NahG plants induced the JA pathway, which was downregulated in WRKY45 -knock down plants, linking the resistant and susceptible phenotypes to the JA pathway. Consistently, the susceptibility phenotype in the WRKY45 -knock down plants was recovered by foliar JA application. These results point to a model in which WRKY45 modulates a crosstalk in resistance against Striga by positively regulating both SA/BTH and JA pathways. How can we apply what we learnt here to the plant, vector and virus interactions? The Speaker. Josiah is visiting from Biosciences for eastern and central Africa (BecA) hub in Nairobi. He is studying the crop-vector-virus interaction using bean-aphid-virus as a model. He is currently visiting the Baulcombe and Carr labs to analyse RNA -Seq data obtained from virus -infected plants aiming to find differentially regulated genes that could be affecting disease outcomes.

This talk is part of the Plant Sciences Talks series.

This talk is included in these lists:

• Cambridge Infectious Diseases
• Tom ap Rees, Department of Plant Sciences

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