Systematics Of Paederina From China And Study Of Ketosynthase Gene

Paederina is a big subtribe in Paederinae (Coleoptera:Staphylinidae) all over the world except Antarctica. Many species in the subtribe are natural enemies of the important agricultural pests. Pederin, a polyketides extracted from Paederus Curtis, is a non-protein insect toxin. Like other polyketides, it displays potent and selective bioactivities that trigger biomedical interests. Up to date, taxonomy on Paederina has focused on the external morphology while related molecular systematic studies are rarely reported and phylogenetic relationships among taxa in Paederina are unknown. In the current study, on the basis of traditional morphological characters, the phylogenetic relationship among taxa in Chinese Paederina are analyzed via COI and COII genes sequences. Besides, one about1000bp fragment of Ketosynthase (KS) was amplified applying degenerate primers designed based on the conservative regions of PKS. This gene functions were speculated in biosynthetic pathway of Pederin. After about4years' work, the main results are as follows:1. Study on Systematics and fauna of PaederinaFour genera and45species (subspecies) from Paederina in China were described, including a new species:Paederus mengyangensis sp. nov. and a new recorded species in Yunnan Province:Paederus melampus Erichson,1840. Paederus coxalis Fauvel,1895is classified to Paederus (Eopaederus) Scheerpeltz,1957based on black retral antennae and tibia, primitive aedeagus.The distribution of Paederina in Chinese zoogeographical regions was analysed in detail and the Oriental species dominate the Palaearctic species in Paederina of China. Different species possess different distribution regions and different zoogeographical regions have different species. Endemisms at species level of Paederina are abundant in China amounting to26species, taking up57.58%of the fauna of China. There are16species distributing in one region.2. Molecular systematics of PaederinaOne COI gene of about800bp and one COII gene of about700bp were amplified from14species of Paederina using universal primers, respectively. BLAST alignment indicated that COI gene is homologous with GenBank's closest sequence, between82%-96%, and for COII gene the rate accounts for78%-82%. The COI and COII genes are homogeneity tested with PAUP*4beta10. The value of P (0.89) showed that two samples can be homogeneous adopting to conjoint analysis. This paper discussed the phylogenetic relationship among taxa in Chinese Paederina based on molecular systematics based on COâ…  and COâ…¡ genes.After phylogenetic signal detection, both transition and transversion exhibit a good linear relationship with genetic distance when the value of genetic distance is less than0.88in COâ…  and COâ…¡ genes. Transversion tends saturated and transition with genetic distance still has a good linear relationship, when genetic distance is more than0.88. Both transition and transversion with genetic distance possess good linear relationship in COâ… +COâ…¡ gene, indicating that the data implys strong phylogenetic information instead of random data.Analysis of base sequences of COâ… , COâ… , COâ… +COâ…¡ genes shows that T, C, A, G base average concentration ranges are35.9%-37.1%,15.3%-15.5%,32.4%-33.6%and14.8%-15.1%, respectively. Average content of A+T in different sites of codon is64.5%-68.2%,66.9%-75.8%a nd68.5%-73.2%, respectively. The results suggest that codon in different sites biased towards A+T. Transversion was higher than transition in COâ… , COâ…¡ and COâ… +COâ…¡ gene, and S/V is0.43-0.60.Phylogenetic trees are built on COâ… , COâ…¡, COâ… +COâ…¡ genes using adjacent connection method (NJ), minimum evolution (ME) and maximum parsimony (MP), respectively. Results show that trees of COâ… +COâ…¡ gene are the same with those of COâ…  gene. The paper analyses the result using trees of COâ… +COâ…¡ genes with high confidence. Homaeotarsus pimeri of Paederini and Aleochara brevipennis Gravenhorst,1806of Aleocharinae are chosen as outgroups. The result shows that Paederus (Gnathopaederus) Chapin,1927is a monophyletic group. Paederus (Harpopaederus) Scheerpeltz,1957might be a paraphyletic group. P.(Eopaederus) Scheerpeltz,1957and Paederus (Heteropaederus) Scheerpeltz,1957unite to a branch in trees of NJ, ME and MP on COâ… , COâ…¡ and COâ… +COâ…¡ gene, and the two are very similar in external morphology. The molecular phylogeny and morphological studies also prove the two subgenus closest as a sister group. Paederus describendus Willers,2001and Paederus (Paederus) Fabricius,1775are closest relatives, but P. describendus Willers,2001without wings can not be classified to the subgenus with hind wings. Three phylogenetic trees based on COâ… , COâ…¡, COâ… +COâ…¡ genes showed that P. coxalis Fauvel,1895should be classified to P.(Eopaederus) Scheerpeltz,1957. The results are consistent with those of morphological classification. Paederus melampus Erichson,1840resembles Paederus tamulus Erichson,1840in external morphology and a close phylogenetic relationship exists between them. 3. Study of KetosynthaseThe degenerate primers of Ketosynthase (KS) gene were designed and in total11samples of Paederus were amplified. Only females of Paederus fuscipes Curtis,1826from4different collections were amplified with a fragment of about1000bp, named pedKS gene. pedKS gene is homologous with the KS gene of Pseudomonas to76%-86%. NJ phylogenetic tree of representative KS gene from NCBI shows that pedKS gene possesses a close phylogenetic relationship with FAD-dependent oxidoreductase gene. Homologous gene in Pseudomonas fluorescens with pedKS synthesizes pyridine six membered rings by redox reaction. It is predicted that pedKS may also participate in the synthesis of pyran six rings in Pederin by oxidation reduction.