Effect of ITS Pseudogene on the Phylogenetic Study of Quercus (Fagaceae) and Its Revelation on the Plant Molecular Phylogenetics

Sequences of ITS in nrDNA is one of the widely used markers in angiosperm systematics.Many early reports of ITS region (ITS 1,5.8S and ITS 2) variation in flowering plants indicated that nrDNA arrays within individuals are homogeneous.However,recent studies have discovered that individuals often contain potentially non-functional nrDNA copies (pseudogenes).These findings suggest that complete concerted evolution should not be assumed when embarking on phylogenetic studies using nrDNA sequences.ITS pseudogene has been detected in the genus of Quercus L.and misled the phylogenetic reconstruction,which made this genus frequently focused in the related studies.The authors take this genus as an example to discuss the influence of the pseudogene on the phylogenetic study,conclude that combining application of molecular evolution and classic taxonomy knowledge in plant systematics study may lead to more convincible results.