Lopes Lucas Dantas, Futrell Stephanie L, Bergmeyer Emma, Hao Jingjie, Schachtman Daniel P
Department of Agronomy and Horticulture, Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588-0660, United States.
FEMS Microbiol Ecol. 2023 Feb 28;99(3). doi: 10.1093/femsec/fiad019.
Root exudates shape the rhizosphere microbiome, but little is known about the specific compounds in root exudates that are important. Here, we investigated the impacts of the plant-synthesized phytohormones indole-3-acetic acid (IAA) and abscisic acid (ABA) exuded by roots on the maize rhizobacterial communities. To identify maize genotypes that differed in the root exudate concentrations of IAA and ABA, we screened hundreds of inbred lines using a semi-hydroponic system. Twelve genotypes with variable exudate concentrations of IAA and ABA were selected for a replicated field experiment. Bulk soil, rhizosphere, and root endosphere samples were collected at two vegetative and one reproductive maize developmental stage. IAA and ABA concentrations in rhizosphere samples were quantified by liquid chromatography-mass spectrometry. The bacterial communities were analyzed by V4 16S rRNA amplicon sequencing. Results indicated that IAA and ABA concentrations in root exudates significantly affected the rhizobacterial communities at specific developmental stages. ABA impacted the rhizosphere bacterial communities at later developmental stages, whereas IAA affected the rhizobacterial communities at the vegetative stages. This study contributed to our knowledge about the influence that specific root exudate compounds have on the rhizobiome composition, showing that the phytohormones IAA and ABA exuded by roots have a role in the plant-microbiome interactions.
根系分泌物塑造了根际微生物群，但对于根系分泌物中重要的特定化合物却知之甚少。在此，我们研究了根系分泌的植物合成激素吲哚-3-乙酸（IAA）和脱落酸（ABA）对玉米根际细菌群落的影响。为了鉴定IAA和ABA根系分泌物浓度存在差异的玉米基因型，我们使用半水培系统筛选了数百个自交系。选择了12个IAA和ABA分泌物浓度不同的基因型进行重复田间试验。在玉米的两个营养生长阶段和一个生殖生长阶段采集了土壤、根际和根内圈样本。通过液相色谱-质谱法定量根际样本中的IAA和ABA浓度。通过V4 16S rRNA扩增子测序分析细菌群落。结果表明，根系分泌物中的IAA和ABA浓度在特定发育阶段显著影响根际细菌群落。ABA在发育后期影响根际细菌群落，而IAA在营养生长阶段影响根际细菌群落。这项研究有助于我们了解特定根系分泌物化合物对根际微生物群组成的影响，表明根系分泌的植物激素IAA和ABA在植物与微生物群的相互作用中发挥作用。
