Potential use of high-throughput sequencing of soil microbial communities for estimating the adverse effects of continuous cropping on ramie (Boehmeria nivea L. Gaud).

Xia Zheng,Duanqing Wu,Xiaomin Xu,Shouwei Tang,Touming Liu,Siyuan Zhu,Qiuzhong Dai,Raffaella Balestrini,Yanzhou Wang

doi:10.1371/journal.pone.0197095

Xia Zheng, Duanqing Wu + Show 7 more

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https://doi.org/10.1371/journal.pone.0197095

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Abstract

Ramie (Boehmeria nivea L. Gaud) fiber, one of the most important natural fibers, is extracted from stem bark. Continuous cropping is the main obstacle to ramie stem growth and a major cause of reduced yields. Root-associated microbes play crucial roles in plant growth and health. In this study, we investigated differences between microbial communities in the soil of healthy and continuously cropped ramie plants, and sought to identify potential mechanisms whereby these communities could counteract the problems posed by continuous cropping. Paired-end Illumina MiSeq analysis of 16S rRNA and ITS gene amplicons was employed to study bacterial and fungal communities. Long-term monoculture of ramie significantly decreased fiber yields and altered soil microbial communities. Our findings revealed how microbial communities and functional diversity varied according to the planting year and plant health status. Soil bacterial diversity increased with the period of ramie monoculture, whereas no significant differences were observed for fungi. Sequence analyses revealed that Firmicutes, Proteobacteria, and Acidobacteria were the most abundant bacterial phyla. Firmicutes abundance decreased with the period of ramie monoculture and correlated positively with the stem length, stem diameter, and fiber yield. The Actinobacteria, Chloroflexi, and Zygomycota phyla exhibited a significant (P < 0.05) negative correlation with yields during continuous cultivation. Some Actinobacteria members showed reduced microbial diversity, which prevented continuous ramie cropping. Ascomycota, Zygomycota, and Basidiomycota were the main fungal phyla. The relatively high abundance of Bacillus observed in healthy ramie may contribute to disease suppression, thereby promoting ramie growth. In summary, soil weakness and increased disease in ramie plants after long-term continuous cropping can be attributed to changes in soil microbes, a reduction in beneficial microbes, and an accumulation of harmful microbes.

Highlights

IntroductionRamie fiber is naturally produced, can be extracted from stem bark, and possesses several excellent characteristics, such as long strands, smooth texture, and high tensile strength
Problems linked to continuous cropping represent some of the main hindrances to the development of the ramie industry
Elucidating potential microbial communitystructure mechanisms that could improve continuous cropping tolerance are highly important for ramie production in China

Summary

Introduction

Ramie fiber is naturally produced, can be extracted from stem bark, and possesses several excellent characteristics, such as long strands, smooth texture, and high tensile strength. Ramie contains a high level of crude protein in its leaves and young stems, and is used for livestock forage [1]. Ramie must have a high vegetable yield to be useful for fiber and feed [2]. Ramie is one of the oldest fiber and feed crops in China, and is an important natural fiber crop in India and other Southeast Asian and Pacific Rim countries [3]. Problems related to continuous cropping are widespread in agriculture, both in annual crops (such as cotton, cucumbers, and potatoes) and in perennial plants (such as apples, peaches, ramie, and sugarcane) [4,5,6,7]

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