Intraspecific variation in the Populus balsamifera drought transcriptome

Drought is a major limitation to the growth and productivity of trees in the ecologically and economically important genus Populus. The ability of Populus trees to contend with drought is a function of the responsiveness of their genome to this environmental insult, involving reconfiguration of the transcriptome to appropriately remodel growth, development and metabolism. The Populus drought transcriptome is shaped by interspecific genotypic variation, but the extent to which intraspecific variation shapes the drought transcriptome has not yet been examined. Here we test hypotheses aimed at examining the extent of intraspecific variation in the drought transcriptome. Transcriptome remodeling in response to water-deficit conditions was examined in six different Populus balsamifera L. genotypes using Affymetrix GeneChip technology. There were significant differences in the transcriptomes of the genotypes in response to water-deficit conditions; however, a common species-level response could also be identified across all individuals. Genotypes that had more similar drought-responsive transcriptomes also had fewer genotypic differences, as determined by microarray-derived single feature polymorphism (SFP) analysis, suggesting that responses may be conserved across individuals that share a greater degree of genotypic similarity. This work highlights the fact that a core species-level response can be defined; however, the underpinning genotype-derived complexities of the drought response in Populus must be taken into consideration when defining both species- and genus-level responses. 72 arrays total. 6 genotypes, 2 time points. 2 water regimes. 3 biological replicates per treatment