Metabolite profiling of rhizosphere soil of different allelopathic potential rice accessions

Abstract

Background: Identification of the allelopathy-interrelated metabolites from the allelopathic rice rhizosphere is crucial to understand the allelopathic mechanism of rice, which in turn can promote its applications to farming. In this study, the metabolites from the rhizosphere soil of five different rice lines, including allelopathic rice accession PI312777 (PI) and non-allelopathic rice accession Lemont (Le) as well as their genetic derivatives (e.g., phenylalanine ammonia-lyase (PAL) gene overexpression transgenic lines of PI and Le, namely, PO and LO respectively, and PAL RNA interference line of PI, namely, PR) were identified and comparatively analyzed to explore the positive compounds that are involved in the process of rice allelopathy. Results: The results showed that 21 non-polar compounds and 21 polar compounds differed in content in the rhizosphere soil of PI and Le, which include several volatile fatty acids and long-chain fatty acids. The relative contents of fatty acids also differed between PAL overexpressing or RNA interference (RNAi)-silenced line and their wild-type respectively. Acetic acid content also differed among groups, i.e., it is higher in the high allelopathic potential rice. Further analysis showed that different metabolites from the ADS8 resin-extracted phase were more abundant than that those from the ADS21 resin-extracted phase, suggesting that the allelochemicals in root exudates of allelopathic rice are mainly non-polar substances. KEGG annotation of these differential metabolites revealed that these compounds were related to nutrient metabolism, secondary metabolite synthesis, signaling substance synthesis, and toxin degradation. Conclusions: Rice allelochemicals deposited in the ADS8 resin-extracted phase were more abundant than those in the ADS21 resin-extracted phase. Allelochemicals in root exudates of allelopathic rice are mainly non-polar substances, and long-chain fatty acids are considered as allelopathy interrelated metabolites.

Nutrient and moisture limitation reveal keystone metabolites that link switchgrass rhizosphere metabolome and microbiome dynamics

“…These rhizosphere metabolites likely consist of a large fraction of the plant exudates, microbial products, and background C compounds present in the bulk soil. A number of studies have analyzed metabolites present in rhizosphere soil of maize, Arabidopsis, wheat, rice, wild oat (13,(83)(84)(85)(86). However few studies have identified changes of rhizosphere metabolites in soil in response to abiotic stressors.…”

The core metabolome and exudation dynamics of three phylogenetically distinct plant species

“…For example, exudates collected in deionized water often contained higher levels of carbon and amino acids 15,21,22 , likely due to the strong osmotic imbalance between root and solvent. Exudate collection duration also influences the metabolic profile 15,23 Few studies analyzed exudates from soil-grown plants, which is usually done with spatial resolution using membranes or leachate collection , or by washing pots with water or organic solvent 24,25 . The presence of microbes in nonsterile settings or of a soil matrix leads to the detection of a complex metabolite profile.…”

The Promises, Challenges, and Opportunities of Omics for Studying the Plant Holobiont

“…Because of major technical advancements in mass spectrometry, we now know a great deal about root exudate composition in model species such as Arabidopsis [ 127 , 128 , 129 ], maize [ 130 ], and rice [ 131 , 132 ] and their effects on associated microbiota [ 133 , 134 , 135 ]. Today, there are still a small number of examples of metabolomics being applied to study root exudates in either field [ 136 , 137 ] or greenhouse soils [ 138 , 139 ]; however, recent experimental advancements promise to address challenges related to non-sterile soil matrices [ 140 ].…”