The Damage Caused by Decline Disease in Bayberry Plants through Changes in Soil Properties, Rhizosphere Microbial Community Structure and Metabolites.

Zheping Yu,Zhenshuo Wang,Temoor Ahmed,Xiliang Zheng,Haiying Ren,Xingjiang Qi,Muchen Zhang,Hongyan Wang,Bin Li,Shuwen Zhang

doi:10.3390/plants10102083

Abstract

Decline disease causes serious damage and rapid death in bayberry, an important fruit tree in south China, but the cause of this disease remains unclear. The aim of this study was to investigate soil quality, microbial community structure and metabolites of rhizosphere soil samples from healthy and diseased trees. The results revealed a significant difference between healthy and diseased bayberry in soil properties, microbial community structure and metabolites. Indeed, the decline disease caused a 78.24% and 78.98% increase in Rhizomicrobium and Cladophialophora, but a 28.60%, 57.18%, 38.84% and 68.25% reduction in Acidothermus, Mortierella, Trichoderma and Geminibasidium, respectively, compared with healthy trees, based on 16S and ITS amplicon sequencing of soil microflora. Furthermore, redundancy discriminant analysis of microbial communities and soil properties indicated that the main variables of bacterial and fungal communities included pH, organic matter, magnesium, available phosphorus, nitrogen and calcium, which exhibited a greater influence in bacterial communities than in fungal communities. In addition, there was a high correlation between the changes in microbial community structure and secondary metabolites. Indeed, GC–MS metabolomics analysis showed that the healthy and diseased samples differed over six metabolic pathways, including thiamine metabolism, phenylalanine–tyrosine–tryptophan biosynthesis, valine–leucine–isoleucine biosynthesis, phenylalanine metabolism, fatty acid biosynthesis and fatty acid metabolism, where the diseased samples showed a 234.67% and 1007.80% increase in palatinitol and cytidine, respectively, and a 17.37–8.74% reduction in the other 40 metabolites compared to the healthy samples. Overall, these results revealed significant changes caused by decline disease in the chemical properties, microbiota and secondary metabolites of the rhizosphere soils, which provide new insights for understanding the cause of this bayberry disease.

Highlights

IntroductionBayberry (Myrica rubra) is an important fruit tree in southern China that is cultivated on approximately 334,000 hectares and has an annual output of approximately 950,000 tons
The results of this study indicated that there was a significant difference in bayberry rhizosphere soil microbiota between healthy and diseased samples
redundancy discriminant analysis (RDA) of microbial communities and soil properties indicated that pH, organic matter, magnesium, available phosphorus, nitrogen and calcium are the main variables of bacterial and fungal communities, where the influence of these six main variables in bacterial communities was greater than that in fungal communities

Summary

Introduction

Bayberry (Myrica rubra) is an important fruit tree in southern China that is cultivated on approximately 334,000 hectares and has an annual output of approximately 950,000 tons. It is an important Figmedicinal plant, and its extract contains antioxidants that can fight inflammation, allergies, diabetes, cancer, bacterial infection, and diarrhea [1,2]. It is well known that the main disease of bayberry is twig blight, which is mainly caused by Pestalotiopsis versicolor and Pestalotiopsis microspora [3]; the infected plants may die within one to four years. In recent years, bayberry plants have been infected by a new 4.0/). No pathogenic microbe has been successfully isolated from the infected bayberry plants, a lot of work has been carried out on this disease

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