UK PlantSci 2013 & the Journal of Experimental Botany

Catherine Kidner
University of Edinburgh

Running time: 00:23:19 min

Using transcriptomes to understand tropical diversity

ABSTRACT

Decreasing sequencing costs makes it feasible to develop genetic resources for any organism. We are taking advantage of this to study the forces that underlie tropical diversity. Currently we have two projects, one developing genetic resources to study speciation in Begonia and the second to determine the role herbivore pressure has in producing and maintaining diversity in the tropical tree genus Inga. For Begonia we have generated four transcriptomes, a draft genome and a genetic map. QTL analysis of ecophysiological traits, micromorphology, plant architecture and reproductive features have identified loci regulating the variation seen between a seasonally dry forest and a wet rainforest species, indicating that some of the changes involved in the switch between habitats could be genetically simple. Transcriptome analysis highlights chloroplast-localised genes as showing evidence of diversifying selection between Begonia species, suggesting that there is strong selective pressure on the photosynthetic apparatus from low light environments with high energy sunflecks. Our work on Inga is in collaboration with Lissy Coley, Tom Kusar (University of Utah, Toby Pennington (RBGE) and Graham Stone (University of Edinburgh). Inga is a large genus of neotropical trees with little morphological variation between species and distributions that overlap. It has been proposed that herbivore pressure has lead to species-level diversification in secondary metabolism as a defense response. Transcriptomes were generated from expanding leaves from three species growing in B.C. I. Panama. Genes which showed strong (> x50) variation between species were enriched for those involved in secondary synthesis including the shikimate, catechol and flavonol pathways. The combination of this work with biochemical analysis and herbivore load data will hopefully allow us to identify the key changes which allow species to co-exist.

 

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