Differences in the chemical composition and content of root exudates of dominant coniferous and broadleaf tree species in subalpine forests of western Sichuan,China
Root exudates act as messengers in plant-soil-microbial communication and regulation.The mediating role of root exudates in rhizospheric ecological processes has received considerable attention.However,basic knowledge of the chemical composition and content of the root exudates of the dominant tree species in forest ecosystems remains scarce.In this study,two coniferous dominant(Picea asperata and Abies faxoniana)and two broadleaf dominant(Betula albo-sinensis and Betula platyphylla)tree species were selected as research objects in the subalpine forests of western Sichuan.The root exudates of the tree species were obtained using an in situ collection device.The results of GC-TOF-MS,variance analysis,and orthogonal partial least squares discriminant analysis showed that:(1)a total of 97 types of chemical substances were identified in the root exudates of four coniferous and broadleaf tree species,including six alcohols,26 organic acids,17 amino acids,five sugar acids,6 sugar alcohols,seven sugars,three esters,and 24 other organic compounds.The relative content of alcohol compounds was the highest in the root exudates of the coniferous and broadleaf trees and the categories of amino and organic acids were relatively rich;(2)significant differences were noted between the relative contents of the chemical components in the root exudates of coniferous and broadleaf trees at the chemical category level;the relative alcohol content in root exudates of coniferous trees was 1.7 times that of broadleaf trees.Meanwhile,the relative contents of amino acids,organic acids,sugars,sugar acids,sugar alcohols,and other organic compounds were 1/3,1/6,1/18,1/56,1/16,and 1/4 of those of broadleaf trees,respectively;(3)a total of 29 key differential metabolites were found between the root exudates of coniferous and broadleaf trees and the relative contents of key differential metabolites varied significantly,among which;amino acid-related metabolic pathways showed the most significant differences.Overall,the results showed significant differences in the chemical composition and relative content of the root exudates of dominant coniferous and broadleaf tree species in the subalpine forests of western Sichuan and revealed the key differential metabolites between their root exudates.
root exudateconiferous and broadleaf tree specieschemical compositiondifferential metabolitesGC-TOF-MS
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