Page Banner

United States Department of Agriculture

Agricultural Research Service

Genetic Characterization of Rice Traits and Mapping Populations - Recent Accomplishments
headline bar

 

  1. DEVELOPED THE LEMONT X TEQING GENE-MAPPING POPULATION NOW USED WORLDWIDE FOR GENE AND MARKER RESEARCH

Permanent mapping populations provide an efficient means for identifying genes and studying their associations with various plant traits. A permanent rice gene-mapping population developed by this project was the first population to be well adapted to research in the U.S. This population provides more precise and accurate characterization of genes because it exhibits marker segregation ratios that are less genetically skewed (closer to Mendelian expectations) and consists of a larger set of progeny lines than other populations. The population was developed over a decade, and derives from a cross between ‘Lemont’, a U.S. rice variety with good yield potential and grain quality, and ‘Teqing’, a very high yielding variety from China. This population is now being used by more than 15 research groups worldwide.

 

  1. DETERMINED THE CHROMOSOMAL LOCATION OF MORE THAN 160 GENES

The mapping of genes for different traits in the same population allows us to better understand possible interactions between the various genes and traits. Genes have been mapped by this project in the Lemont/Tequing gene-mapping population for the following traits:

Plant height
Days to flowering
Rice grain shape, size, weight
Resistance to sheath blight disease (causal org. Rhizoctonia solani)
Resistance to rice blast disease (causal org. Pyricularia grisea)
Plant architecture:

  Tiller angle
  Leaf angle
  Leaf size

Seedling vigor & component traits:

  Mesocotyl length
  Coleoptile length
  Seed germination rates

Field yield & component traits:

  Number of florets/panicle
  Kernel Weight
  Panicle weight
  Panicle number/plant
  Tiller number/plant
  Location of node(s) forming tillers
  Location of nodes on the main culm

Location of 161 Genes (QTLs) Mapped by Dr. Pinson and Various Collaborators
using the Lemont x Teqing gene-mapping population created by Dr. Pinson's team

QTL's Mapped to Chromosome 1-6
Click to enlarge image

QTL's Mapped to Chromosome 7-12
Click to enlarge image

 

  1. DETERMINED BEST METHOD FOR FINDING HIDDEN GENES OF COMPLEX TRAITS

Analysis of the individual physiological and genetic components that interact to determine a complex trait can enhance the identification and molecular mapping of important genes. Examples of this can be seen in the Figures above by comparing locations of grain weight genes (complex trait) with genes for grain length, width, and thickness (component traits). Component trait analysis revealed the existence of additional genes, genes that were "hidden" in the analysis of the complex trait, such at those for grain length, width, or thickness on chromosomes 2, 7, 9, and 11. Analysis of component trait data also provided more accurate and precise estimates of gene locations. On chromosomes 2, 5 and 10, component trait analysis revealed the location of two linked genes where complex trait analysis had suggested the existence of single genes inaccurately located between the more precisely mapped component trait genes.

 


Last Modified: 1/24/2005
Footer Content Back to Top of Page