Analysis of metabolites of Amomum villosum fruits and their correlation with the rhizospheric soil physicochemical properties and microorganisms under rubber plantations

【Objective】 This study aimed to characterize the metabolite in Amomum villosum fruits at different growth years under rubber plantations and to examine their correlations with rhizosphere soil physicochemical properties and rhizosphere microbial communities， so as to provide a theoretical basis for the pharmacological evaluation of Amomum villosum at different growth years and for the exploitation and utilization of its metabolite resources. 【Method】 Fruit samples of Amomum villosum harvested at four different ages （3-，4-，5-， and 6-year old） were labeled （SR3， SR4， SR5， and SR6）， and their metabolite content was determined using gas chromatography coupled with time-of-flight mass spectrome-try （GC-TOF-MS）. Pairwise and multi-group comparisons were performed to analyze the differential metabolites in Amomum villosum fruits at different growth years under rubber plantations， and significant differential metabolites were identified for KEGG metabolic pathway enrichment analysis， through which pathways of extremely significant enrichment were identified. Correlation analyses were conducted between extremely significant differential metabolites and the physicochemical properties of the rhizosphere soil， as well as between the dominant microbial phyla in the rhizosphere and the extremely significant differential metabolites. 【Result】 A total of 261 metabolites were identified from Amomum villosum fruit samples. The numbers of significant different metabolites detected in the pairwise comparison groups were as follows： SR4 vs SR3 （13）， SR5 vs SR3 （54）， SR6 vs SR3 （49）， SR4 vs SR5 （54）， SR4 vs SR6 （40）， and SR5 vs SR6 （5）. The SR5 vs SR3 and SR4 vs SR5 comparison groups each yielded the highest count of significant differential metabolites （54）. In the SR4 vs SR5 comparison group， up-regulated metabolites predominated （34）. Of the 62 metabolic pathways， 5 were identified as extremely significant enrichment pathways （P<0.001）； the lowest P values were found in the metabolic pathway of ABC transporter proteins pathway， and followed by the flavonoid biosynthesis pathway. Correlation analysis revealed strong correlations among most of the extremely significant differential metabolites， except for available potassium content that showed no significant correlation with any metabolite （P>0.05， the same below）， and the rest rhizospheric soil physicochemical properties showed strong correlations with seventeen extremely significant differential metabolites. Among the five dominant bacterial phyla， Proteobacteria had a significantly negative correlation with raffinose （P<0.05， the same below）； Actinobacteria had a significantly positive correlation with acetol. Within the five dominant fungal phyla， Zygomycota had a significantly positive correlation with glucoheptonic acid， and Glomeromycota exhibited strong correlations with the majority of the extremely significant differential metabolites. 【Conclusion】 Seventeen extremely significant differential metabolites are identified from comparison groups of Amomum villosum fruits at diffe-rent growth years under rubber plantations， suggesting that contents of some metabolites such as acetol， raffinose， and lysine may be influenced by rhizosphere soil physicochemical properties and microbial communities.