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United States Department of Agriculture

Agricultural Research Service

Research Project: Field Testing of Sorghum Lines for Variation in P Efficiency Due to the Pup1 Locus

Location: Plant, Soil and Nutrition Research

2013 Annual Report

1a.Objectives (from AD-416):
The primary objective of this proposal is to identify genes related to tolerance to phosphorous (P) deficiency in sorghum, with a focus on homologs of the rice phosphorous uptake efficiency gene, Pup1, in sorghum. Once sorghum P efficiency genes are identified, this information and new knowledge will be transferred to the Sorghum Molecular Breeding (SorghumMB) project for deployment into breeding programs. This project is based on the work of an interdisciplinary research team from Embrapa (Brazil), USDA-ARS at Cornell University in Ithaca, JIRCAS in Japan, IRRI in the Philippines, Moi University in Kenya, ICRISAT in Mali and Niger, and INRAN in Niger. The findings from this research sets the foundation for a molecular breeding program targeting marginal soil areas in southern Mali, Niger and Kenya and other areas of Sub-Saharan Africa to improve food security and farmer’s income.

The specific objectives are: 1. Identify homologs of rice Pup1 that are associated with traits related to P deficiency tolerance in sorghum and also clarify the role of the sorghum Al tolerance gene, SbMATE, in tolerance to low P.

2. Validate genes associated with P deficiency tolerance in sorghum.

1b.Approach (from AD-416):
This project will undertake a comparative genomics strategy based on association analysis to validate the role of sorghum homologs of Pup1 as bona fide P deficiency tolerance genes. Here, Pup1 validation in sorghum will be done within a molecular genetic framework that should allow for the isolation of other P deficiency tolerance genes and their pyramiding in sorghum for exploring additive effects. In addition, this same platform will be used to study a possible role of AltSB in improving P acquisition in sorghum. This project sets the foundation for a molecular breeding program targeting marginal soil areas in Mali, Niger, Kenya and other African NARS to improve food security and farmer’s income.

3.Progress Report:

In FY 2013, we improved upon an experimental system we developed and use to image whole root systems of crop plants to quantify traits that describe different aspects of the shape of the root systems, which is called root system architecture. The original system, which we have named RootReader3D, is for the high throughput imaging of root systems in 2D and reconstructing those images into a 3D representation of the root system. The RootReader 3D system then automatically quantifies 20 different root system architecture (RSA) traits that quantify both total root system growth and growth of individual root types, as well as the shape and form of the entire root system. This allows researchers to quantify RSA traits associated with deeper root systems or more shallow and wider root systems that might be more effective for acquiring nutrients such as water and nitrogen that move quickly through the soil (deeper root systems) or nutrients such as phosphorous that interact more with soil components and thus tend to move slowly through the soil and accumulate in the top soil (shallow root systems). Our initial system used plants with their roots grown in glass cylinders containing gelled nutrient media, in order to capture the 3D RSA. We found that roots of certain plant species did not grow optimally in this gel media and the research was limited to fairly small volume cylinders and thus young root systems. Therefore an improved growth system was developed where roots are grown in nutrient solution using a series of fine plastic grids spaced at vertical intervals, allowing the roots to grow freely while the grid maintains the 3D architecture of the root systems. This new growth system opens up many more avenues for our RSA research, as it enables the study of a much larger number of crop species, the imaging of root systems of significantly older plants which allows for the study of more fully developed root systems. With the new system, we are currently studying RSA in a wide range of plant species, including corn, sorghum, cucumber, and turf grass species.

Last Modified: 4/17/2014
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