The Stephen Moose Corn Functional Genomics Lab At Illinois

Illinois Long-term Selection Experiment

Project Overview:

In 1896, University of Illinois scientists initiated an experiment that is now the longest running continuous genetics experiment in higher plants.  Beginning with an open pollinated variety of maize, Burr’s White, they selected for ears with the highest or lowest concentrations of grain protein or oil.  Over a century has elapsed, and one-hundred ten cycles of recurrent selection has created twelve populations that vary significantly in their grain protein and oil composition.  Our lab maintains this experiment, but our research focus is on the protein selections.  Illinois High Protein (IHP) and Illinois Low Protein (ILP) represent the known extremes for protein concentrations in maize (see figure below).  After forty-eight cycles of forward selection, breeders reversed the direction of selection by selecting low protein ears from IHP and high protein ears from ILP, thereby creating two new lines, Illinois Reverse High Protein (IRHP) and Illinois Reverse Low Protein (IRLP).  Collectively, these four strains are referred to as the Illinois Protein Strains (IPS).  The IPS provide a unique source of genetic material with which to make comparisons both between and among the strains and generations, at the DNA, mRNA and protein levels, with a goal of elucidating the dynamics of evolutionary changes during these intervals.  They are also a useful resource for discovering genes that contribute to seed protein accumulation, not only in maize, but other crop species.

Selection Responses in the Illinois Protein Strains
Selection responses in the Illinois Protein Strains.  Illinois High Oil (IHO) and Illinois Low Oil (ILO) are part of the same source population, but were not selected for protein.  Thus, they illustrate the effects of random genetic drift.

Selection for grain protein concentration in the IPS has specifically altered the concentration of the 19 and 22kD α-zein endosperm storage proteins, which constitute approximately 50% of total seed protein.  A red fluorescent protein (mRFP1) transgene has been fused to the floury2 gene, encoding one of the 22kD class of α-zeins (Dr. Jackson’s lab, Cold Spring Harbor).  This floury2 RFP transgene is a useful tool for investigating zein gene regulation, as illustrated by crossing to inbred lines derived from the IPS (IHP1, ILP1, IRHP1 and IRLP1).  RFP expression shows the expected differences in color intensity, dark pink in IHP, light pink in ILP, and medium pink in IRHP and IRLP (see figure below).

Map of the FLOURY2-mRFP1 fusion protein transgene construct


Map of the FLOURY2-mRFP1 fusion protein transgene construct

Data:

A comprehensive compilation of data and publications related to the Illinois Long-term Selection Experiment is available at the University of Illinois Digital Environment for Access to Learning and Scholarship (IDEALS).  To download an Excel spreadsheet containing data generated from the most recent cycle of the Illinois Long-term Selection Experiment, click here.

Posters:

2004   2005   2007   2008   2009   2010

People:

Han Zhao
Christine Lucas