© 2005 Heron Publishing—Victoria, Canada
Seasonal variation in gene expression for loblolly pines (Pinus taeda) from different geographical regions
Suk-Hwan Yang (1) and Carol A. Loopstra (1, 2)
1. Institute for Plant Genomics and Biotechnology and The Department of Forest Science, Molecular and Environmental Plant Science,
Texas A&M University, College Station, TX 77843-2123, USA / 2. Corresponding author (c-loopstra@tamu.edu) / Received July 28, 2004; accepted January 15, 2005; published online June 1, 2005
Summary
In developing xylem, gene expression levels vary in different genotypes, at different stages of development, throughout a
growing season, and in response to stresses. Commercially important characteristics such as wood-specific gravity are known
to differ with seed source. For example, when grown on a common site, the specific gravity of Arkansas loblolly pine (Pinus taeda L.) trees is greater than that of Louisiana loblolly pine, and Texas loblolly pines have a greater specific gravity than
loblolly pines from the Atlantic coast. A microarray analysis was performed to examine variation in gene expression among
trees from different geographical sources when grown on a common site, and seasonal variation in gene expression in each seed
source. We used microarrays containing 2171 expressed sequence tags (ESTs) with putative functions of interest, selected from
several loblolly pine xylem partial cDNA libraries and a shoot tip library. Genes with significant variation in expression
for each factor were identified. Many genes preferentially expressed in latewood compared with earlywood were for proteins
involved in cell wall biosynthesis. Variation in gene expression among trees from the two seed sources in each growing season
suggests that there may be more differences between South Arkansas trees and South Louisiana trees in latewood than in earlywood.
Variation in gene expression among trees from different regions may reflect adaptation to different environments.
Keywords:
adaptation, earlywood, latewood, population, microarray, real-time RT-PCR, seed source.
