PDF(Pubmed)
Abstract：
Pecan (Carya illinoinensis) and Chinese hickory (Carya cathayensis) are important commercially cultivated nut trees. They are phylogenetically closely related plants; however, they exhibit significantly different phenotypes in response to abiotic stress and development. The rhizosphere selects core microorganisms from bulk soil, playing a pivotal role in the plant\'s resistance to abiotic stress and growth. In this study, we used metagenomic sequencing to compare the selection capabilities of seedling pecan and seedling hickory at taxonomic and functional levels in bulk soil and the rhizosphere. We observed that pecan has a stronger capacity to enrich rhizosphere plant-beneficial microbe bacteria (e.g., Rhizobium, Novosphingobium, Variovorax, Sphingobium, and Sphingomonas) and their associated functional traits than hickory. We also noted that the ABC transporters (e.g., monosaccharide transporter) and bacterial secretion systems (e.g., type IV secretion system) are the core functional traits of pecan rhizosphere bacteria. Rhizobium and Novosphingobium are the main contributors to the core functional traits. These results suggest that monosaccharides may help Rhizobium to efficiently enrich this niche. Novosphingobium may use a type IV secretion system to interact with other bacteria and thereby influence the assembly of pecan rhizosphere microbiomes. Our data provide valuable information to guide core microbial isolation and expand our knowledge of the assembly mechanisms of plant rhizosphere microbes. IMPORTANCE The rhizosphere microbiome has been identified as a fundamental factor in maintaining plant health, helping plants to fight the deleterious effects of diseases and abiotic stresses. However, to date, studies on the nut tree microbiome have been scarce. Here, we observed a significant \"rhizosphere effect\" on the seedling pecan. We furthermore demonstrated the core rhizosphere microbiome and function in the seedling pecan. Moreover, we deduced possible factors that help the core bacteria, such as Rhizobium, to efficiently enrich the pecan rhizosphere and the importance of the type IV system for the assembly of pecan rhizosphere bacterial communities. Our findings provide information for understanding the mechanism of the rhizosphere microbial community enrichment process.
摘要：
山核桃（山核桃）和山核桃（山核桃）是重要的商业栽培坚果树。它们是系统发育密切相关的植物；然而，它们对非生物胁迫和发育的反应表现出明显不同的表型。根际从块状土壤中选择核心微生物，在植物对非生物胁迫的抗性和生长中起着举足轻重的作用。在这项研究中,我们使用宏基因组测序来比较山核桃幼苗和山核桃幼苗在块状土壤和根际的分类和功能水平上的选择能力。我们观察到山核桃具有更强的富集根际植物有益微生物细菌的能力(例如，根瘤菌,Novoshingoum,Variovorax,鞘氨醇,和鞘氨醇单胞菌）及其相关功能特征比山核桃。我们还注意到ABC运输商(例如，单糖转运蛋白)和细菌分泌系统(例如，IV型分泌系统）是山核桃根际细菌的核心功能性状。根瘤菌和新囊虫是核心功能性状的主要贡献者。这些结果表明，单糖可能有助于根瘤菌有效地丰富这一生态位。新鞘氨醇可以使用IV型分泌系统与其他细菌相互作用，从而影响山核桃根际微生物组的组装。我们的数据提供了有价值的信息，可以指导核心微生物的分离并扩展我们对植物根际微生物组装机制的了解。重要性根际微生物组已被确定为维持植物健康的基本因素，帮助植物对抗疾病和非生物胁迫的有害影响。然而,到目前为止,对坚果树微生物组的研究很少。这里,我们观察到山核桃幼苗有显著的“根际效应”。我们还证明了山核桃的核心根际微生物组和功能。此外，我们推导出了有助于核心细菌的可能因素，如根瘤菌，有效丰富山核桃根际和IV型系统对山核桃根际细菌群落组装的重要性。我们的发现为理解根际微生物群落富集过程的机理提供了信息。
