Transcriptional profiles of the annual growth cycle in Populus deltoides
Sunchung Park (1), Daniel E. Keathley (1) and Kyung-Hwan Han (1, 2)
1. Department of Forestry, Michigan State University, East Lansing, MI 48824-1222, USA / 2. Corresponding author () / Received February 14, 2007; accepted June 7, 2007; published online January 2, 2008
Summary
Cycling between vegetative growth and dormancy is an important adaptive mechanism in temperate woody plants. To gain insights
into the underlying molecular mechanisms, we carried out global transcription analyses on stem samples from poplar (Populus deltoides Bartr. ex Marsh.) trees grown in the field and in controlled environments. Among seasonal changes in the transcriptome, up-regulation
of defense-related genes predominated in early winter, whereas signaling-related genes were up-regulated during late winter.
Cluster analysis of the differentially expressed genes showed that plants regulated seasonal growth by integrating environmental
factors with development. Short day lengths induced some cold-associated genes without concomitant low temperature exposure,
and enhanced the expression of some genes when combined with low temperature exposure. These mechanisms appear to maintain
closer synchrony between cold hardiness and climate than would be achieved through responses to temperature alone.
