1a.Objectives (from AD-416):
A multidisciplinary team involving USDA, Embrapa, JIRCAS, IRRI and Moi University will work on the identification and characterization of genes associated with maize P efficiency (tolerance to low P). The objectives for this research project include:
1. Pup-1 candidate gene identification in maize
2. QTL/gene mapping for P use efficiency in maize
3. Inheritance studies on maize root architecture under high and low P
4. Validation of maize Pup-1 candidate genes and if necessary, novel P efficiency QTL (if maize Pup1 homologues are not functional in P efficiency)
1b.Approach (from AD-416):
A multidisciplinary team involving USDA, Embrapa, JIRCAS, IRRI and Moi University will work on the identification and characterization of genes associated with maize P efficiency (tolerance to low P). Bioinformatics will be used to identify homologues of the rice Pup-1 (P uptake efficiency) gene in maize and a set of markers for these genes will be developed. An Embrapa inbred line panel that was developed for breeding for P efficiency be phenotyped in the field for this trait measured as grain yield under contrasting P conditions and in the greenhouse/lab for root architecture traits; also the Buckler association panel will be phenotyped for P efficiency and root architecture traits in the green house/lab at USDA-ARS. Finally, a maize RIL population from the cross of a highly P efficient tropical maize line (L3) with a P inefficient line (L22) will be phenotyped to identify QTLs for P acquisition, internal P efficiency and root architecture traits. Also, candidate genes for p efficiency will be mapped on the same RIL population, in order to verify the co-segregation of Pup-1 homologs with QTLs for different P-efficiency traits. Finally, association analysis using Embrapa’s elite inbred lines panel and the Buckler maize association panel will be carried out to validate candidate genes.
In FY 2012, used root system architecture methods were developed in this lab to study the root systems of corn lines that differ in their ability to tolerate low levels of phosphorous (P) in the soil. We found that the lines that do better on low P soils have a more branched root system that can better explore the surface soils for P. We will begin looking for candidate genes that may be responsible for these differences in root system architecture.