Pan Ying, Li Guihao, Su Lei, Zheng Pengfei, Wang Yaping, Shen Zhuo, Chen Zigui, Han Qiuying, Gong Jun
School of Ecology, Sun Yat-sen University, Shenzhen, China.
Laboratory of Microbial Ecology and Matter Cycle, School of Marine Sciences, Sun Yat-sen University, Zhuhai, China.
Front Microbiol. 2022 Jun 13;13:901741. doi: 10.3389/fmicb.2022.901741. eCollection 2022.
Seagrass form high productive ecosystems in coastal environments. However, the effects of these coastal plants on the structure and function of the belowground eukaryotic microbiome remain elusive. In this study, we characterized the community of microbial eukaryotes (microeukaryotes) in both vegetated and unvegetated sediments using 18S rRNA gene amplicon sequencing and quantitative PCR. Analysis of sequencing data showed that the eelgrass () colonization decreased the alpha diversity indices of benthic microeukaryotes. Apicomplexa represented an average of 83% of reads across all samples, with a higher proportion at the vegetated sites. The taxonomic community structure was significantly different between these two types of sediments, for which the concentration of in sediment porewater and salinity could account. Phylogenetic analyses of long 18S rRNA genes (around 1,030 bp) indicated these apicomplexan parasites are closely related to gregarine . Determination of 18S rRNA gene abundances provided evidence that the eelgrass markedly promoted the biomass of the gregarine and all microeukaryotes in the seagrass-colonized sediments and confirmed that the gregarine was hosted by a polychaete species. Significantly higher gene abundances of heterotrophs and mixotrophs were found at the vegetated sites, which could be explained by the finer sediments and short supply of dissolved inorganic nitrogen, respectively. The pigmented protists were more abundant in 18S rRNA gene copies at the lower and higher pH levels than at the intermediate. Nevertheless, the fractions of heterotrophs and phototrophs in the community were significantly related to porewater N:P ratio. These results indicate that seagrass colonization significantly induces an increase in overall biomass and a decrease in diversity of benthic microeukaryotes, making them more heterotrophic. This study also highlights that the hotspot of eukaryotic parasites could be linked with the high productivity of a natural ecosystem.
海草在沿海环境中形成高生产力的生态系统。然而，这些沿海植物对地下真核微生物群落结构和功能的影响仍不清楚。在本研究中，我们使用18S rRNA基因扩增子测序和定量PCR对有植物覆盖和无植物覆盖的沉积物中的微生物真核生物（微真核生物）群落进行了表征。测序数据分析表明，鳗草（）的定殖降低了底栖微真核生物的α多样性指数。顶复门在所有样本的读数中平均占83%，在有植物覆盖的位点比例更高。这两种类型的沉积物之间的分类群落结构存在显著差异，沉积物孔隙水中的浓度和盐度可以解释这种差异。对长18S rRNA基因（约1030 bp）的系统发育分析表明，这些顶复门寄生虫与簇虫密切相关。18S rRNA基因丰度的测定提供了证据，表明鳗草显著促进了海草定殖沉积物中簇虫和所有微真核生物的生物量，并证实簇虫由一种多毛类物种寄生。在有植物覆盖的位点发现异养生物和混合营养生物的基因丰度显著更高，这分别可以由更细的沉积物和溶解无机氮供应不足来解释。色素原生生物在较低和较高pH水平下的18S rRNA基因拷贝数比在中间pH水平下更丰富。然而，群落中异养生物和光合生物的比例与孔隙水氮磷比显著相关。这些结果表明，海草定殖显著导致底栖微真核生物的总生物量增加和多样性降低，使其更具异养性。本研究还强调，真核寄生虫的热点可能与自然生态系统的高生产力有关。
