Differential Protein Expression Analysis of Two Sugarcane Varieties in Response to Diazotrophic Plant Growth-Promoting Endophyte Enterobacter roggenkampii ED5.

Yang-Rui Li,Zhen Lu,Yong-Xiu Xing,Qaisar Khan,Dao-Jun Guo,Dong-Ping Li,Mukesh K Malviya,Krishan K Verma,Xiu-Peng Song,Rajesh Kumar Singh,Ying Qin,Anjney Sharma,Pratiksha Singh

doi:10.3389/fpls.2021.727741

Abstract

Plant endophytic bacteria have many vital roles in plant growth promotion (PGP), such as nitrogen (N) fixation and resistance to biotic and abiotic stresses. In this study, the seedlings of sugarcane varieties B8 (requires a low concentration of nitrogen for growth) and GT11 (requires a high concentration of nitrogen for growth) were inoculated with endophytic diazotroph Enterobacter roggenkampii ED5, which exhibits multiple PGP traits, isolated from sugarcane roots. The results showed that the inoculation with E. roggenkampii ED5 promoted the growth of plant significantly in both sugarcane varieties. 15N detection at 60 days post-inoculation proved that the inoculation with strain ED5 increased the total nitrogen concentration in the leaf and root than control in both sugarcane varieties, which was higher in B8. Biochemical parameters and phytohormones in leaf were analyzed at 30 and 60 days after the inoculation. The results showed that the inoculation with E. roggenkampii ED5 improved the activities of superoxide dismutase (SOD), catalase (CAT), NADH-glutamate dehydrogenase (NADH-GDH), glutamine synthetase (GS), and endo-β-1,4-glucanase, and the contents of proline and indole acetic acid (IAA) in leaf, and it was generally more significant in B8 than in GT11. Tandem Mass Tags (TMT) labeling and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to perform comparative proteomic analysis in the sugarcane leaves at 30 days after inoculation with strain ED5. A total of 27,508 proteins were detected, and 378 differentially expressed proteins (DEPs) were found in the treated sugarcane variety B8 (BE) as compared to control (BC), of which 244 were upregulated and 134 were downregulated. In contrast, a total of 177 DEPs were identified in the treated sugarcane variety GT11 (GE) as compared to control (GC), of which 103 were upregulated and 74 were downregulated. The DEPs were associated with nitrogen metabolism, photosynthesis, starch, sucrose metabolism, response to oxidative stress, hydrolase activity, oxidative phosphorylation, glutathione metabolism, phenylpropanoid metabolic process, and response to stresses in Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database. To the best of our knowledge, this is the first proteomic approach to investigate the molecular basis of the interaction between N-fixing endophytic strain E. roggenkampii ED5 and sugarcane.

Highlights

Sugarcane (Scacharum spp. interspecific hybrids) is a major sugar and bioenergy crop worldwide (Li and Yang, 2015; Bordonal et al, 2018; Parsaee et al, 2019)
The superoxide dismutase (SOD) activity in sugarcane variety GT11 was enhanced at 30 days and decreased at 60 days after inoculation with ED5 as compared to control; it was higher in sugarcane variety B8 after the inoculation of strain ED5 at both time points (30 and 60 days) (Figure 1A)
The POD activity was found higher in GT11 and did not change in B8 at 30 days, whereas it was reduced in GT11 and increased in B8 at 60 days (Figure 1C)

Summary

Introduction

Sugarcane (Scacharum spp. interspecific hybrids) is a major sugar and bioenergy crop worldwide (Li and Yang, 2015; Bordonal et al, 2018; Parsaee et al, 2019). Plant growth-promoting bacteria (PGPB) are the microorganisms that can colonize in plant tissues or rhizospheric soil and show beneficial effects on plant development, biotic or abiotic stresses, and nutrient assimilation (Esitken et al, 2010; Piromyou et al, 2011; OrozcoMosqueda et al, 2020). It is effective to use these N-fixing bacteria to improve nitrogen nutrition in plants which is necessary for crop production, especially in sugarcane (Wei et al, 2014; Singh et al, 2017). Some reports are available on the isolation of N-fixing microorganisms with PGP traits from rhizospheric soil or tissues of sugarcane, such as Klebsiella variicola, Kosakonia sacchari, Streptomyces chartreusis, Pseudomonas spp., Herbaspirillum seropedicae, Stenotrophomonas maltophilia, Kosakonia radicincitans, Bacillus spp., Pantoea dispersa, and Enterobacter asburiae (Chen et al, 2014; Wang Z. et al, 2016; Li et al, 2017; Antunes et al, 2019; Singh et al, 2020, 2021b)

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