Omics Approaches for Understanding Plant Defense Response

Plants are the major components that contribute to energy, environment, and ecosystem, and they are also the primary producers of the food chain. Despite their importance, their sustenance in the environment is challenged by several biotic and abiotic factors. Among the biotic factors, diseases and infections cause devastative results, and in agriculture, such biotic stresses caused by pathogens lead to a severe decrease in yield and productivity, which ultimately challenges food security. Plants have also developed sophisticated molecular mechanisms to defend the pathogens, thus leading to resistance or tolerance to the given disease. Understanding the mechanism of tolerance or resistance is now imperative to gain insights into the molecular machinery underlying such defense responses, which could be further exploited to develop disease-resistant plant species. To study the response of plants to pathogens, different approaches have been developed that interrogates the system at varying levels of disease infection. These approaches are generically called “omics” approaches that enable the study of plant systems at the genome, transcriptome, proteome, and metabolome levels. The advent of tools and techniques has advanced these omics approaches, and the knowledge generated so far has been proven useful in developing elite cultivars resistant to pathogens. Transgene-based approaches and/or molecular breeding-based techniques are now being used to develop such improved varieties, whereas the introduction of genome editing tools like CRISPR/Cas9 is expected to expedite the crop improvement programs. Given this, the present chapter enumerates the use of different omics approaches, namely, transcriptomics, proteomics, and metabolomics, to delineate the molecular mechanism underlying disease response, and how this information could be integrated to advance the current understanding of plant defense response.