W373 GeneticControl of Natural Variation in Maize Shoot Apical Meristem Architecture

Date: Sunday, January 15, 2012
Time: 4:35 PM
Room: Golden Ballroom
Addie M. Thompson , University of Minnesota
Lin Li , University of Minnesota
James E. Crants , University of Minnesota
Jillian Foerster , University of Wisconsin-Madison
Jinliang Yang , Iowa State University
Natalia de Leon , University of Wisconsin-Madison, Madison, WI
Shawn Kaeppler , University of Wisconsin-Madison
Nathan M. Springer , University of Minnesota
Patrick S. Schnable , Iowa State University
Marja Timmermans , Cold Spring Harbor Laboratory, Cold Spring Harbor, NY
Jianming Yu , Kansas State University
Michael Scanlon , Cornell University, Ithaca, NY
Gary Muehlbauer , University of Minnesota
The shoot apical meristem (SAM), containing a group of undifferentiated stem cells, is responsible for generating all shoot-derived organs.  The SAM initiates leaves while preserving the pool of meristematic cells.  As a result, its overarching structure remains relatively constant during vegetative development.  Here, maize SAM architecture was investigated in a set of the intermated B73xMo17 recombinant inbred line (IBMRIL) population. These parental lines represent the majority of differences in SAM height found among a range of diverse inbreds examined.  To determine genetic control of natural variation in SAM architecture, quantitative trait loci (QTL) analysis was conducted.  Measurements taken to define SAM architecture included height, width, midpoint-width, and arc length to the cleft of the first incipient leaf primordia (P1), as well as cell counts along the arc length in the L1, and P1 height.  Cell size, height/width ratio, and volume were also calculated.  As adult plant architecture is determined in part by regulatory mechanisms acting in the SAM, correlations and coincidence of phenotypic QTLs from previously studied traits in the same population were analyzed.  Of 21 QTL associated with one or more SAM traits, 14 were found to be coincident with other morphological QTL, reflecting correlations observed among these traits.  To identify genes with allelic variation in expression and regulation underlying phenotypic QTL, expression-QTL (eQTL) mapping was conducted by quantifying gene expression using SAM-enriched tissue of the same lines.  Coincidence of the two mapping analyses will be discussed as a means of identification of potential master regulators of maize morphology.