IDENTIFICATION OF GENES CONTROLLING ROOT SYSTEM ARCHITECTURE TRAITS IMPORTANT FOR P ACQUISITION AND AL TOLERANCE FOR CROP ON ACID SOILS
Plant, Soil and Nutrition Research
2013 Annual Report
1a.Objectives (from AD-416):
The objectives of the research are to identify genes that are involved in crop plant tolerance to low phosphorous (phosphorous efficiency) and toxic levels of Al (Al tolerance) in acid soils, with a focus on the regulation and signaling between P efficiency and Al toxicity.
1b.Approach (from AD-416):
The approaches will involve the use of digital imaging and computer-based reconstruction of root system architecture (RSA) in 3D to phenotype soybean and sorghum mapping populations for QTL controlling different components of RSA. The research will set the stage for future research identifying genes important for tolerance to low P and Al tolerance for crop production on acid soils.
In FY 2013, we continued to develop and have finalized new methods to impose phosphorous (P) deficiency under laboratory conditions where we can grow crop plant species in hydroponics but mimic the real world situation for a low P soil. On typical low P soils, most of the P (as phosphate) moves slowly in the soil and tends to bind to certain chemical components of clay minerals in the soil. Thus much of the P is in a relatively unavailable form in the “topsoil”, while the “subsoil” has much less P. We are working on an approach where the root system of intact plants is grown in a pouch that has paper on one side and a clear plastic viewing sheet on the other. The paper is saturated with the nutrient solution of choice. We use a specially designed and constructed metal chamber to vacuum infiltrate insoluble calcium phosphate particles into the top layer of the paper, which will mimic the top soil of a low P soil which contains higher levels of P than the subsoil (as P moves very slowly down into the soil). Then, the very bottom of the paper pouch is placed in contact with –P nutrient solution which wicks up the paper pouch and provides all nutrients except P, which is only supplied by the calcium phosphate particles fixed into the top of the paper pouch. Thus, more P efficient rice and sorghum genotypes will need to have root systems that shallowly proliferate into the “topsoil” where they can release organic acids which bind the calcium and release the phosphate ions from the calcium phosphate particles for uptake into the root.