Functional Investigation of Plant Growth Promoting Rhizobacterial Communities in Sugarcane.

Mingjia Li,Lei Zheng,Kefei Zhang,Xinxin Li,Yongjia Zhong,Guoqiang Huang,Hong Liao,Ran Liu,Cunhu Wang,Yanjun Li,Yachun Su,Wenjing Ma,Xing Fu

doi:10.3389/fmicb.2021.783925

Mingjia Li, Lei Zheng + Show 11 more

Open Access

https://doi.org/10.3389/fmicb.2021.783925

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Abstract

Plant microbiota are of great importance for host nutrition and health. As a C4 plant species with a high carbon fixation capacity, sugarcane also associates with beneficial microbes, though mechanisms underlying sugarcane root-associated community development remain unclear. Here, we identify microbes that are specifically enriched around sugarcane roots and report results of functional testing of potentially beneficial microbes propagating with sugarcane plants. First, we analyzed recruitment of microbes through analysis of 16S rDNA enrichment in greenhouse cultured sugarcane seedlings growing in field soil. Then, plant-associated microbes were isolated and assayed for beneficial activity, first in greenhouse experiments, followed by field trials for selected microbial strains. The promising beneficial microbe SRB-109, which quickly colonized both roots and shoots of sugarcane plants, significantly promoted sugarcane growth in field trials, nitrogen and potassium acquisition increasing by 35.68 and 28.35%, respectively. Taken together, this report demonstrates successful identification and utilization of beneficial plant-associated microbes in sugarcane production. Further development might facilitate incorporation of such growth-promoting microbial applications in large-scale sugarcane production, which may not only increase yields but also reduce fertilizer costs and runoff.

Highlights

Plant-associated microbes colonize organs throughout host plants, with distinctive microbial communities forming in the different niches plants present, and the collection of organisms forming a holobiont (Tringe et al, 2005; Hassani et al, 2018)
16S rDNA sequencing spanning the V5–V7 regions was employed to investigate the composition of bacterial communities in the rhizospheres and roots of sugarcane plants
Rarefaction curves of observed OTU plateaued after 60% sampling (Supplementary Figure 3), suggesting that the sequencing depth for all the samples was enough to cover most of the bacterial in the rhizosphere and root compartments

Summary

Introduction

Plant-associated microbes colonize organs throughout host plants, with distinctive microbial communities forming in the different niches plants present, and the collection of organisms forming a holobiont (Tringe et al, 2005; Hassani et al, 2018). Sugarcane is a C4 crop with high photosynthetic efficiency and rapid growth, which requires large amounts of mineral nutrients, especially nitrogen, to support growth and coordinate nutrient homeostasis with carbon fixation capacity (Gopalasundaram et al, 2012; Carvalho et al, 2014; de Oliveira et al, 2016). This has led to excessive nitrogen applications in sugarcane production (Boddey et al, 2003). Increasing sugarcane production while simultaneously protecting agroecosystems through more efficient nutrient acquisition and decreased fertilization are interconnected practical objectives for improving sugarcane production (Rosenblueth et al, 2018)

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