Declined symptoms in Myrica rubra: The influence of soil acidification and rhizosphere microbial communities

Abstract

Declined symptoms seriously damaged the growth and development of Myrica rubra, a typical bayberry tree in southern of Zhejiang Province, China. However, knowledge on the mechanisms involved in this decline remains largely unknown. Here, we compared the physicochemical properties, microbial communities as well as metabolites in rhizospheric soil of healthy and declined Myrica rubra trees from four orchards. We found that planting bayberry aggravated soil acidification in all orchards. Surprisingly, compared with healthy trees, the pH decreased and the correlation between nutrients (N, P, K) and metal elements (Cu, Cr, Ni, As, Cd) changed significantly (p < 0.01) in the rhizospheric soil of declined trees. Moreover, bacteria affiliated with Acidobacteriota, Firmicutes, Rozellomycota and Mucoromycota showed considerable enrichment; whereas in genus level, the relative abundance of Acidothermus, Trichoderma, Geminibasidium decreased by 2.9%, 6.7%, and 33.9%, respectively. Besides, the connection in bacterial or fungal communities became more complicated but unstable. These discoveries along with the upregulation of myristic acid and cinnamic acid via metabolome analysis further indicated the aggravated soil acidification and the varied microbial communities and metabolites that resulted in the declined symptoms in Myrica rubra. This study provides new insights into the causes of declined in bayberry trees and can assist the prevention and treatment of declined trees basing on the plant-soil-microbe interactions.