The BioTechnology Institute, University of Minnesota, 140 Gortner Lab, 1479 Gortner Ave., St Paul, MN, 55108-6106, USA.
Laboratorio de Ecología Microbiana Aplicada (EMAlab), Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Ave. Francisco Salazar 01145, Temuco, Chile.
Sci Rep. 2019 Mar 20;9(1):4950. doi: 10.1038/s41598-019-41160-x.
Several studies have demonstrated the relevance of endophytic bacteria on the growth and fitness of agriculturally-relevant plants. To our knowledge, however, little information is available on the composition, diversity, and interaction of endophytic bacterial communities in plants struggling for existence in the extreme environments of Chile, such as the Atacama Desert (AD) and Patagonia (PAT). The main objective of the present study was to analyze and compare the composition of endophytic bacterial communities associated with roots and leaves of representative plants growing in Chilean extreme environments. The plants sampled were: Distichlis spicate and Pluchea absinthioides from the AD, and Gaultheria mucronata and Hieracium pilosella from PAT. The abundance and composition of their endophytic bacterial communities was determined by quantitative PCR and high-throughput sequencing of 16S rRNA, respectively. Results indicated that there was a greater abundance of 16S rRNA genes in plants from PAT (10 to 10 copies g DNA), compared with those from AD (10 to 10 copies g DNA). In the AD, a greater bacterial diversity, as estimated by Shannon index, was found in P. absinthioides, compared with D. spicata. In both ecosystems, the greater relative abundances of endophytes were mainly attributed to members of the phyla Proteobacteria (14% to 68%), Firmicutes (26% to 41%), Actinobacteria (6 to 23%) and Bacteroidetes (1% to 21%). Our observations revealed that most of operational taxonomic units (OTUs) were not shared between tissue samples of different plant species in both locations, suggesting the effect of the plant genotype (species) on the bacterial endophyte communities in Chilean extreme environments, where Bacillaceae and Enterobacteriacea could serve as keystone taxa as revealed our linear discriminant analysis.
已有多项研究表明，内生细菌与农业相关植物的生长和适应性密切相关。然而，我们对智利极端环境中植物内生细菌群落的组成、多样性和相互作用知之甚少，这些环境包括阿塔卡马沙漠（AD）和巴塔哥尼亚（PAT）。本研究的主要目的是分析和比较与智利极端环境中代表性植物的根和叶相关的内生细菌群落的组成。采样的植物分别为：来自 AD 的须芒草（Distichlis spicate）和苦艾（Pluchea absinthioides），以及来自 PAT 的白珠树（Gaultheria mucronata）和垂头菊（Hieracium pilosella）。通过定量 PCR 和 16S rRNA 高通量测序分别确定了它们内生细菌群落的丰度和组成。结果表明，PAT 植物的 16S rRNA 基因丰度更高（10 到 10 拷贝 g DNA），而 AD 植物的丰度则较低（10 到 10 拷贝 g DNA）。在 AD，与 D. spicata 相比，P. absinthioides 的细菌多样性更高，Shannon 指数估计值更大。在这两个生态系统中，内生菌的相对丰度更高，主要归因于变形菌门（14%到 68%）、厚壁菌门（26%到 41%）、放线菌门（6%到 23%）和拟杆菌门（1%到 21%）的成员。我们的观察结果表明，大多数操作分类单元（OTUs）在两个地点不同植物组织样本之间没有共享，这表明植物基因型（物种）对智利极端环境中内生细菌群落的影响，其中芽孢杆菌科和肠杆菌科可能作为关键分类群，正如我们的线性判别分析所揭示的那样。
