Legumes are important agricultural and feed crops second only to cereal crops. Grain legumes such as chickpea, lentils and the common bean provide 33 % of human dietary protein and up to 60 % in developing countries (Gentzbittel et al. 2015). Soybeans and alfalfa are important for animal feed and fodder as well as intercropping systems because of their ability to fix nitrogen. Because of their agronomic, nutritional and environmental benefits, it is imperative to understand factors that may influence agricultural yield and/or quality of feed.
Plants produce a diverse array of specialized metabolites to ensure adaptation to their ecological niche by functioning in pollinator attraction, herbivore repellence and pathogen resistance (Gershenzon and Dudareva 2007). Terpenes, a major class of specialized metabolites, play an important role in gene-by-environment interactions as shown in crops like rice and maize (Murphy and Zerbe 2020).
Terpenes have been well described in their response to biotic factors. However, comparatively fewer investigations have been performed for abiotic stress. In the changing face of climate, where heat, nutrients, and water all become important factors influencing agricultural productivity and food security, it is essential to understand the chemical response strategy employed in response to abiotic stressors. In this proposal, we will investigate the chemical response strategy (focusing on the terpenome) of Medicago truncatula to select abiotic conditions.
Our long-term goal is to understand how terpenes coordinate chemical responses to the environment. The objective of this research proposal is to study the influence of terpenes to abiotic stress response in M. truncatula. Our central hypothesis, based on literature and our preliminary data, indicates that M. truncatula responds with distinct chemical signatures in response to abiotic stress. A central challenge is deciphering the complex transcriptional metabolic changes in response to environmental stress. We will accomplish the objectives of this proposal through the following specific aims:
Goal 1: Develop a terpene-based abiotic stress marker. Our preliminary data shows a terpene synthase, that produces germacrene-D-4-ol, highly upregulated under various abiotic stress conditions. We will perform a functional biochemical analysis of the pathway towards de novo pathway elucidation and structural determination by NMR of intermediate compounds.
Goal 2: Assessing the response of terpenes to abiotic stress. We will define the importance of the physiological role of terpene synthases in response to select abiotic conditions (water, salt and nutrients) guided by the preliminary data.
Outcomes and Impacts: The investigations proposed here represent essential steps towards deciphering the gene-to-metabolite relationship of M. truncatula and a fuller understanding of the reconfiguration of plant metabolism with a focus on the terpenome in response to abiotic stress. We anticipate that knowledge of stress response strategies will provide fundamental information to further investigations of metabolism-based mechanistic responses. The foundational information gained will inform molecular breeding efforts in agriculturally relevant legume crops due to rapidly altering climate conditions. The project establishes a pipeline that can be used to investigate other legumes of economic relevance and data for obtaining federal research support.
Target Audience: The work is designed for undergraduates under the guidance of a graduate student/postdoctoral research associate. This enables us to train and expose undergraduates to a range of techniques including analytical chemistry, protein biochemistry, molecular biology bioinformatics and plant physiology. We anticipate our efforts will contribute to the retention of students in STEM, in particular chemical sciences and contribute to the development of skilled personnel to bioeconomy.
