Polysaccharide biosynthesis-related genes explain phenotype-genotype correlation of Microcystis colonies in Meiliang Bay of Lake Taihu, China

AbstractThe 16S rDNA, 16S-23S rDNA-ITS,cpcBA-IGS,mcygene and several polysaccharide biosynthesis-related genes (epsL andTagH) were analyzed along with the identification of the morphology ofMicrocystiscolonies collected in Lake Taihu in 2014.M. wesenbergiicolonies could be distinguished directly from other colonies usingespL.TagHdivided all of the samples into two clusters but failed to distinguish different phenotypes. Our results indicated that neither morphology nor molecular tools including 16S rDNA, 16S-23S ITS andcpcBA-IGS could distinguish toxic and non-toxic species among the identifiedMicrocystisspecies. No obvious relationship was detected between the phenotypes ofMicrocystisand their genotypes using 16S, 16S-23S andcpcBA-IGS, but polysaccharide biosynthesis-related genes may distinguish theMicrocystisphenotypes. Furthermore, the sequences of the polysaccharide biosynthesis-related genes (espLandTagH) extracted fromMicrocystisscums collected throughout 2015 was analyzed. Samples dominated byM. ichthyoblabe(60–100%) andM. wesenbergii(60–100%) were divided into different clade by bothespLandTagH, respectively. Therefore, it was confirmed thatM. wesenbergiiandM. ichthyoblabecould be distinguished by the polysaccharide biosynthesis-related genes (espLandTagH). This study is of great significance in filling the gap between classification of molecular biology and the morphological taxonomy ofMicrocystis.