Fish diversity and molecular taxonomy in the Prydz Bay during the 29th CHINARE

In 2013, the 29th Chinese National Antarctic Research Expedition（CHINARE） prospected the Prydz Bay on the Antarctic continental shelf, and the Chinese R/V Xuelong icebreaker sampled all of the examined locations. The nature of Antarctic fish diversity in the high-latitude Prydz Bay is virtually unknown, and the accuracy of relevant estimates has not been established. Thus, it is necessary to evaluate this diversity and propose protective measures. In total, ninety-nine specimens were collected from various locations. To overcome uncertainties associated with identifying species based on morphology, DNA barcoding（COI gene） was employed to reconstruct phylogenetic relationships with delimited references from NCBI. Twenty-two species representing six families were unambiguously identified from a neighbor-joining（NJ） tree and barcoding gaps. With the morphological identification, thirteen species were identified correctly, five species were identified correctly at the genus level, and four species were identified at the close sister species level. Notothenioid dominance was not evident in the Prydz Bay, in contrast to other published studies. The low species diversity and catch biomass during this CHINARE were severely constrained by limited fishing methods and localized sites, which led to biased underestimation. Our analyses indicate that DNA barcoding is an effective tool for the identification of fish species in the Prydz Bay. The identification and distribution of Antarctic fish should be an integral component of understanding Antarctic fish biodiversity and biogeography, and large-scale studies are necessary for the further taxonomic identification of Antarctic fish.

Screening of DNA Barcode of Quarantine Phytophthora

Phytophthora is genus of plant-damaging Oomycetes, whose member species are capable of causing enormous economic losses on crops worldwide. In the present study, four candidate genes ITS, CO1, EF-1α and β-tubulin were tested using 123 strains of 80 species of Phytophthora to investigate the feasibility of ser- ving as DNA barcoding markers. The results showed that among the four candidate genes, ITS and CO1 had the highest success rate of PCR amplification and se- quencing, up to 100% and 96.7%. There were obvious barcode gaps in ITS, CO1 andβ-tubulin, but their frequency distributions of intra- and interspecific genetic distances were slightly overlapped. Wilcoxon rank sum test on intraspecific genetic distances of the four genes showed ITS = CO1 = β - tubulin = EF-1α indicating they bad the same effect on intraspecific discrimination, while the test on interspecific genetic distances of the four genes showed ITS 〉 C01 〉 β- tubulin 〉 EF - 1α. In summary, ITS and COl should be used in combination as the primary barcodes, β-tubulin as the complementary barcede for the identification of 11 quaran- tine Phytophthora species.