Metabolite Analysis and Metabolomics in the Study of Biotrophic Interactions between Plants and Microbes

Abstract

Biotrophic plant-microbe interactions depend on the establishment of a nutritional interface allowing nutrient trafficking between plants and microbial symbionts and pathogens. A global re-programming of host and microbial metabolism is at the core of these interactions, and we summarise in this chapter studies on metabolome and, to add interpretational power, transcriptome changes associated with the establishment and maintenance of a range of plant-microbe associations. Pathogenic fungi of crops cause severe economic losses, and factors resulting in improved crop resistance against infection and disease spread are therefore the subject of extensive research projects. We focus in this chapter on three fungal examples, namely Magnaporthe grisea (rice blast), Blumeria graminis (powdery mildew) and Ustilago maydis (corn smut), and discuss how metabolomics technologies critically improve our understanding of resistant and susceptible interactions. Like pathogens, mutualistic symbionts are heterotrophic organisms and depend on nutrients from their hosts, but unlike pathogens these microbial symbionts rarely cause disease symptoms or host death. In contrast, they can improve plant fitness by providing valuable nutrients or protective metabolites to their

Plant Metabolomics in a Nutshell: Potential and Future Challenges

“…Genotype x environment interaction is a topic of basic importance regarding how plants survive and function under what is normally an ever-changing environment (Ahuja et al, 2010;Browne et al, 2011;van Dam & van der Meijden, 2011). Furthermore, its importance in a crop production context enhances the value of this fundamental research (Browne et al, 2011;Draper et al, 2011). Metabolomics research has shown that changes in plant physiology, be they related to genetic or environmental perturbation, often involve widespread alteration in plant biochemistry not specifically restricted to particular pathways (Beale & Sussman, 2011).…”

“…These analyses are regularly focused specifically on aspects of product quality but metabolomics approaches are also regularly applied to tackle problems related to crop fitness involving disease resistance and its molecular basis, plant-insect interactions, mycorhizal interactions, stress effects, etc. (Ahuja et al, 2010;Draper et al, 2011). Through these approaches we are gradually gaining a much more detailed picture of crop biochemistry and its link to nutritional, sensory and other crop-related characteristics.…”

“…While it is also stated above that we are unlikely ever to be able to perform fully holistic metabolite analyses for a range of different reasons, one major current limitation restricting a broader application of metabolomics approaches is the under-representation of key groups of low abundance molecules (Draper et al, 2011). In particular, the general absence of data on key plant hormones such as the gibberellins, auxin and cytokinins restricts our ability to interpret observed phenotypic changes in the context of metabolite biosynthesis.…”

“…Glandular hair cells are also a clear case in point, being often filled with a rich mix of secondary metabolites that may hardly be detectable in adjacent leaf cells (Sumner et al, 2011). Single cell metabolomics would also be highly desirable in investigating the responses of plants at the sub-tissue level at the earliest moments of pathogen attack (Draper et al, 2011). Particularly, resistance mechanisms involving hypersensitive responses can be very rapid, involving just one or a small number of cells.…”

Metabolomics of Arabidopsis Thaliana

“…We have not covered plant pathogen interactions as this topic has been covered extensively elsewhere (Draper et al, 2010). It is fair to say that care in the design of the experiment, sampling of tissue and collection of analytical data are fundamental.…”