ABSTRACT

The global climate change reports and predictions of imminent deterioration in the conditions considered optimal for crop production, has formed the basis for currently identifying drought as one of the major challenges to be dealt with in the coming years. In order to achieve the requirements of food production under variable environmental conditions and increasing human population, understanding the various plants’ stress responses is very relevant. There have been many technological advances in recent years, among which omics technologies have emerged as the forerunner in unraveling intricate plant response patterns. The various omics tools help in identifying the genetic factors controlling drought adaptation by elucidating functions of important genes, their regulators, as well as whole stress response pathways. Rapid advances are being noted in these techniques and novel tools are being developed at a considerable pace. Effective use of these discoveries in a timely manner would serve as the panacea for developing crop plants tolerant to drought as well as other stressful conditions. This chapter focuses on the role of the respective technologies categorized under genomics, transcriptomics, proteomics, and metabolomics approaches for prospecting genes, identification of key regulators/effectors and discovery of specific pathways linked to drought acclimation.

According to the FAO 2014 Hunger Report, achieving the Millennium Development Goal (MDG-1)—of halving the proportion of undernourished people in developing countries—seems possible (https://www.fao.org/hunger/en/). However, the latest National Aeronautics and Space Administration (NASA) Global Climate Change observations indicate elevated levels of atmospheric CO2 and global atmospheric temperature, as well as rapidly diminishing forest cover. According to the report, the present CO2 level in the air is highest in 650,000 years (400.57 ppm), while atmospheric temperature is 1.4 °F more since 1880, and nine out of 10 recorded warmest years on the planet occurred since 2000. Also, forest areas have decreased by 1.5 million km2 (https://climate.nasa.gov/). These facts refect foreseeing of the occurrence of more frequent and higher intensity stressful conditions for crop production. In most cases, drought stress would accompany high light and temperature stresses. In addition, world population is expected to increase by over one third (2.3 billion people) between 2009 and 2050. Mere growth of human population demands a nearly 70% increase in food production (https://www.fao.org/fleadmin/templates/wsfs/docs/Issues_papers/HLEF2050_Global_Agriculture.pdf). Taken together, these reports indicate a need for development of crop varieties with higher biomass and yield potential even under stressful conditions. Drought stress is projected to continue as one of the major constraints for improvement in agricultural productivity. In the dynamic scenario of global climatic conditions, it is crucial to identify and breed for drought tolerant crop varieties. Dissecting the tolerance conferring mechanism would enable crop scientists to use the relevant genes or genomic regions for targeted manipulation of traits in important crop species. Given that drought tolerance is governed by multiple traits, there is a need to use a comprehensive approach to study the adaptive responses in tolerant species.

From the agriculture point-of-view, in order to meet the penultimate goal of creating crops more adept for cultivation in the current scenario of climate change, applications of different “Omics” tools in understanding diverse aspects of plant physiology are numerous. One of the chief advantages of omics technologies is the direct, unbiased monitoring of the various factors governing plant growth and development. This would aid in investigation of the complex interplay between the plant and its environment at various levels; namely, whole genome, specific regions of the genome, transcriptome, proteome, and metabolome. Integration at system level of gene functions would further elucidate the intricacies of gene networks. Now known as “systems breeding,” would lead to accelerated crop improvement strategies. The complex issues related to the analysis of trait architecture, discovery and detection of potential pathogens, understanding various disease epidemiologies, identification of resistance conferring genes, study of specific mutants, regulatory events, signaling and developmental aspects can be addressed effectively using omics. Eventually, it is expected that all the information generated would lead to a clearer elucidation of the pathways associated with plant growth and tolerance to different stressful conditions, and thus, serving as the panacea for crop scientists to achieve the said objective.

With this perspective, the issues discussed here are crop genomics and its relevance in dissecting the complexity of drought adaptive responses; transcriptomics, proteomics, and metabolomics-based approaches for prospecting genes/pathways, identification of key regulators/effectors, and discovery of specific pathways linked to drought adaptation processes.