Abstract
Triploidy is a widespread phenomenon in cultivated and natural breeding plants and it can confer some growth advantages. Here, we analyzed genome-wide gene expression in triploid Populus euramericana (black poplar) using the Affymetrix poplar microarray to detect any possible correlation between triploid vigor and a unique gene expression profile. Among the 38,400 transcripts that were detected in triploid poplar, 1,564 and 2,015 genes were up- or downregulated, respectively, compared with the diploid. The majority of the upregulated genes in the triploid were associated with carbon and nitrogen metabolism, especially lignin and secondary metabolism. Other genes upregulated in the triploid included genes involved in sugar transport, and brassinosteroid (BR) and auxin metabolism. Downregulated genes were mostly related to the assembly and biosynthesis of ribosomes and the nucleosome macromolecular complex. The results suggested that BR and auxin levels were crucial in controlling sugar transport, photosynthesis and cell wall biosynthesis. Downregulated genes were associated with chromatin regulation in the triploid. The information from this analysis could provide an insight into the vigor of triploid poplar.