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INVESTIGATOR: Milner, M.; Assmann, S. M.

PERFORMING INSTITUTION:
PENNSYLVANIA STATE UNIVERSITY
208 MUELLER LABORATORY
UNIVERSITY PARK, PENNSYLVANIA 16802

EXTRA-LARGE G PROTEINS (XLGS) AND THEIR ROLE IN NUTRIENT AND HORMONE REGULATION OF LATERAL ROOT GROWTH

NON-TECHNICAL SUMMARY: To keep America a leader in agriculture, a greater understanding of basic plant processes is needed to help reduce the costly inputs farmers apply to their crops and help feed the ever increasing human population. One of the most costly inputs for farmers today is nitrogen (N) fertilizer. Globally, farmers are adding more than 100 million tons of N fertilizer to their fields every year. If farmers could reduce inputs added to their fields they could reduce costs and still maintain current crop yields. Just how a plant senses the levels of N in the soil and how perceived N levels change root architecture in response to limiting N conditions remains unclear. A better understanding of the signaling mechanism involved in N perception and uptake could result in a substantial savings for farmers. An understanding of the signaling cascade once N is perceived at the root could lead to fewer inputs and more efficient uptake of nutrients from the soil. For the current the research will focus on how a class of proteins called the XLG proteins influence N uptake from the soil as well as if all forms of N uptake are regulated by XLGs or only uptake of nitrate. We will also study how the XLGs influence the root structure to help N uptake. This will help us to understand how N is being absorbed by the root and help to engineer more efficient crops to maximize crop yield and limit excess N being added to the environment.

OBJECTIVES: Overall goal: Reduce costly N fertilizer inputs while maintaining crop yield. Supporting objectives: 1) Uncover which XLG protein(s) alter nitrogen uptake and sensing by measuring uptake and lateral root growth for different N sources and xlg mutant combinations. 2) Use RNAi to identify whether XLG regulation of nitrate response and lateral root development carries over to tomato, and whether XLG knockdown can reduce N fertilizer inputs in the field. 3) Probe alterations in auxin transport in the xlg mutants through auxin reporter gene analysis and crosses with auxin-related mutants. 4) Perform protein-protein interaction tests to assess possible XLG regulation of nitrogen- or auxin-related transcription factors.