Chaudhary, B., Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011, United States, School of Biotechnology, Gautam Budhha University, Greater Noida 201 308 UP, India
Hovav, R., Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011, United States
Flagel, L., Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011, United States
Mittler, R., Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, United States, Department of Plant Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
Wendel, J.F., Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011, United States

Background: Reactive oxygen species (ROS) play a prominent role in signal transduction and cellular homeostasis in plants. However, imbalances between generation and elimination of ROS can give rise to oxidative stress in growing cells. Because ROS are important to cell growth, ROS modulation could be responsive to natural or human-mediated selection pressure in plants. To study the evolution of oxidative stress related genes in a single plant cell, we conducted comparative expression profiling analyses of the elongated seed trichomes ("fibers") of cotton (Gossypium), using a phylogenetic approach. Results: We measured expression changes during diploid progenitor species divergence, allopolyploid formation and parallel domestication of diploid and allopolyploid species, using a microarray platform that interrogates 42,429 unigenes. The distribution of differentially expressed genes in progenitor diploid species revealed significant up-regulation of ROS scavenging and potential signaling processes in domesticated G. arboreum. Similarly, in two independently domesticated allopolyploid species (G. barbadense and G. hirsutum) antioxidant genes were substantially up-regulated in comparison to antecedent wild forms. In contrast, analyses of three wild allopolyploid species indicate that genomic merger and ancient allopolyploid formation had no significant influences on regulation of ROS related genes. Remarkably, many of the ROS-related processes diagnosed as possible targets of selection were shared among diploid and allopolyploid cultigens, but involved different sets of antioxidant genes. Conclusion: Our data suggests that parallel human selection for enhanced fiber growth in several geographically widely dispersed species of domesticated cotton resulted in similar and overlapping metabolic transformations of the manner in which cellular redox levels have become modulated. © 2009 Chaudhary et al; licensee BioMed Central Ltd.