molecular evolution of trehalose-6-phosphate synthase (tps) gene family in populus, arabidopsis and rice分子进化的trehalose-6-phosphate合成酶(tps)基因家族在杨树,拟南芥和水稻.pdfVIP

Molecular Evolution of Trehalose-6-Phosphate Synthase (TPS) Gene Family in Populus, Arabidopsis and Rice 1 2 1 2 Hai-Ling Yang *, Yan-Jing Liu , Cai-Ling Wang , Qing-Yin Zeng * 1 College of Life Sciences and Biotechnology, Beijing Forestry University, Beijing, China, 2 State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China Abstract Trehalose-6-phosphate synthase (TPS) plays important roles in trehalose metabolism and signaling. Plant TPS proteins contain both a TPS and a trehalose-6-phosphate phosphatase (TPP) domain, which are coded by a multi-gene family. The plant TPS gene family has been divided into class I and class II. A previous study showed that the Populus, Arabidopsis, and rice genomes have seven class I and 27 class II TPS genes. In this study, we found that all class I TPS genes had 16 introns within the protein-coding region, whereas class II TPS genes had two introns. A significant sequence difference between the two classes of TPS proteins was observed by pairwise sequence comparisons of the 34 TPS proteins. A phylogenetic analysis revealed that at least seven TPS genes were present in the monocot–dicot common ancestor. Segmental duplications contributed significantly to the expansion of this gene family. At least five and three TPS genes were created by segmental duplication events in the Populus and rice genomes, respectively. Both the TPS and TPP domains of 34 TPS genes have evolved under purifying selection, but the selective constraint on the TPP domain was more relaxed than that on the TPS domain. Among 34 TPS genes from Populus, Arabidopsis, and rice, four class I TPS genes (AtTPS1, OsTPS1, PtTPS1, and PtTPS2) were under stronger purifying selection, whereas