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SUMMARY:Overcoming chemical betrayal: plant defensive signalling against p
 athogens - Dr Josiah Mutuku\, BioSciences East and Central Africa\, Nairob
 i
DTSTART:20151120T140000Z
DTEND:20151120T150000Z
UID:TALK62531@talks.cam.ac.uk
CONTACT:23263
DESCRIPTION:The root hemiparasite witchweed (Striga spp.) is a devastating
  agricultural pest that causes losses of up to 1 billion USD annually in s
 ub-Saharan Africa. Development of resistant crops is one of the cost-effec
 tive ways to address this problem. However\, the molecular mechanisms unde
 rlying resistance are not well understood. To understand molecular events 
 upon Striga infection\, we conducted genome scale RNA-Seq expression analy
 sis using Striga-infected rice roots. We found that transcripts grouped un
 der the gene ontology term "defense response" were significantly enriched 
 in upregulated differentially expressed (DE) genes. In particular\, we fou
 nd that both jasmonic acid (JA) and salicylic acid (SA) pathways were indu
 ced\, 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 suscep
 tibility. The resistant phenotype was recovered by application of JA. By c
 ontrast\, the SA-deficient NahG rice plants were resistant against Striga\
 , indicating endogenous SA is not required for resistance. However\, knock
 ing down WRKY45\, a regulator of the SA/BTH pathway resulted in enhanced s
 usceptibility. 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 susceptibilit
 y phenotype in the WRKY45-knock down plants was recovered by foliar JA app
 lication. These results point to a model in which WRKY45 modulates a cross
 talk 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 a
 nd virus interactions? The Speaker. Josiah is visiting from Biosciences fo
 r eastern and central Africa (BecA) hub in Nairobi. He is studying the cro
 p-vector-virus interaction using bean-aphid-virus as a model. He is curren
 tly 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.
LOCATION:Tom ap Rees\, Department of Plant Sciences
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