CAREER:IDENTIFICATION AND CHARACTERIZATION OF NOVEL GENETIC PLAYERS IN THE EARLY SIGNALING PATHWAYS OF PLANT-MICROBE SYMBIOSES

University Of Wisconsin-Platteville, Platteville WI

Investigators

Abstract

Excessive use of agrochemicals, such as fertilizers and pesticides in intensive agriculture has not only increased the cost of cultivation but also poses severe health hazards and threats to various ecosystems. Sustainable agriculture aims at preserving the natural reserves for the future, demands minimum chemical inputs, promotes efficient nutrient recycling, and enhances the critical microbial-driven processes, such as nutrient acquisition and protection against plant pathogens. Rhizobia and mycorrhizal fungi are the primary groups of beneficial soil microbes, which help the plants in meeting their demand for nitrogen and phosphorous, thereby significantly reducing the exogenous application of nitrogen and phosphate fertilizers. Although mycorrhizal associations are widely prevalent among most land plants, nitrogen-fixing rhizobial associations are limited only to legumes. This project aims at dissecting the molecular mechanisms of legume-rhizobia symbiosis to engineer and introduce this symbiotic machinery into cereal crops. This will be a great boon to the farmers, as the availability of cereal crop cultivars that are capable of establishing symbiotic associations with nitrogen-fixing rhizobia will minimize their cost of cultivation manifold. In addition to furthering existing knowledge on plant-microbe symbioses, the project will provide ample scope for the integration of research and educational goals of the researcher and support unique educational programs dedicated to provide a research based-learning platform to undergraduate students from first-generation, low-income, under-represented minority groups, K-12 teachers and students of Wisconsin public schools. Symbiotic associations between crops and microbes play an essential role in enhancing the productivity and sustainability of our agriculture. The two most important symbioses in agroecosystems that promote crop nutrition are legume root nodulation and arbuscular mycorrhization. Genetic studies in the model legumes, such as Medicago truncatula and Lotus japonicus led to current understanding of the molecular mechanisms controlling the establishment of these mutualistic associations and suggest the existence of a Common Symbiotic Pathway (CSP) between both symbioses, in which Medicago truncatula DOES NOT MAKE INFECTIONS 1, 2 and 3 (DMI1, DMI2 and DMI3) play a central role. This opens the exciting possibility of manipulating this conserved CSP to improve the associations between symbiotic microbes and crop plants. To achieve this exciting goal, a thorough understanding of symbiotic signal transduction machinery is required. This CAREER project aims at identifying and characterizing novel genetic players in the early signaling pathway through genetic suppressor screening followed by mapping the suppressor loci through whole genome sequencing to clone the novel genes for functional characterization. This project will allow the investigators to identify novel components that have been missed in conventional screens for nodulation-defective mutants and generate new knowledge of the molecular mechanisms allowing symbiotic associations that could be applied to legume and non-legume crops. Therefore, this project will not only provide fundamental insights into the molecular mechanisms controlling plant-microbe symbioses, but will also identify potential targets for engineering more efficient nitrogen-fixing associations in cereal crops. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.