Diazotrophic Bacteria Pantoea dispersa and Enterobacter asburiae Promote Sugarcane Growth by Inducing Nitrogen Uptake and Defense-Related Gene Expression

Abstract

Sugarcane is a major crop in tropical and subtropical regions of the world. In China, the application of large amounts of nitrogen (N) fertilizer to boost sugarcane yield is commonplace, but it causes substantial environmental damages, particularly soil, and water pollution. Certain rhizosphere microbes are known to be beneficial for sugarcane production, but much of the sugarcane rhizosphere microflora remains unknown. We have isolated several sugarcane rhizosphere bacteria, and 27 of them were examined for N-fixation, plant growth promotion, and antifungal activity. 16S rRNA gene sequencing was used to identify these strains. Among the isolates, several strains were found to have a relatively high activity of nitrogenase and ACC deaminase, the enzyme that reduces ethylene production in plants. These strains were found to possess nifH and acdS genes associated with N-fixation and ethylene production, respectively. Two of these strains, Pantoea dispersa-AA7 and Enterobacter asburiae-BY4 showed maximum plant growth promotion (PGP) and nitrogenase activity, and thus they were selected for detailed analysis. The results show that they colonize different sugarcane tissues, use various growth substrates (carbon and nitrogen), and tolerate various stress conditions (pH and osmotic stress). The positive effect of AA7 and BY4 strains on nifH and stress-related gene (SuCAT, SuSOD, SuPAL, SuCHI, and SuGLU) expression and the induction of defense-related processes in two sugarcane varieties, GT11 and GXB9, showed their potential for stress amelioration and PGP. Both bacterial strains increased several sugarcane physiological parameters. i.e., plant height, shoot weight, root weight, leaf area, chlorophyll content, and photosynthesis, in plants grown under greenhouse conditions. The ability of rhizobacteria on N-fixing in sugarcane was also confirmed by a 15N isotope-dilution study, and the estimate indicates a contribution of 21–35% of plant nitrogen by rhizobacterial biological N fixation (BNF). This is the first report of sugarcane growth promotion by N-fixing rhizobacteria P. dispersa and E. asburiae strains. Both strains could be used as biofertilizer for sugarcane to minimize nitrogen fertilizer use and better disease management.

Root-Derived Endophytic Diazotrophic Bacteria Pantoea cypripedii AF1 and Kosakonia arachidis EF1 Promote Nitrogen Assimilation and Growth in Sugarcane

“…The technique of 15 N isotope dilution has been frequently utilized to measure the contribution of associative N-fixing systems to graminaceous crops like sugarcane ( Urquiaga et al, 1992 ; Asis et al, 2002 ; Montañez et al, 2009 ; Thaweenut et al, 2011 ; Lin et al, 2012 ; Li et al, 2017 ; Singh et al, 2020c , 2021b ). This study was performed in pots that used total N balance and enriched 15 N fertilizer isotope-dilution methods, and the outcome was impressive.…”

“…The strains were identified by analyzing their 16S rRNA gene sequences amplified from genomic DNA using universal primers pA and pH ( Supplementary Table 2 ) ( Edwards et al, 1989 ), and conditions as described by Singh et al (2021b) . Briefly, pure bacterial cultures were grown in Luria-Bertani (LB) broth for 48 h on a shaker incubator and maintained at 32 ± 2°C for 160 rpm.…”

“…The genera Pantoea and Kosakonia , belong to Enterobacteriaceae family, are non-spore-forming, rod-shaped, and Gram-negative bacteria ( Tambong, 2019 ). Members of Pantoea and Kosakonia genera are known to interact and elicit beneficial effects on plant growth ( Brock et al, 2018 ; Chen and Liu, 2019 ; Romano et al, 2020 ; Singh et al, 2020b , 2021b ; Suman et al, 2020 ), but little is known about their potential for disease control and N-fixation in sugarcane. Considering the widespread occurrence of diseases and the large reduction in N input required in sugarcane crops in China, we studied the disease control and BNF properties of members of Pantoea and Kosakonia genera, and the results are presented here.…”

A Thermotolerant Marine Bacillus amyloliquefaciens S185 Producing Iturin A5 for Antifungal Activity against Fusarium oxysporum f. sp. cubense

“…Plantlets were removed after 72–96 h of growth, rinsed with distilled water, and CLSM was used to check for bacterial colonization. Banana leaf, stem, and root (inoculated and uninoculated) samples were sliced into 1 cm lengths and put on the bridge slide with 10% ( v / v ) of glycerol before being detected with CLSM at varying emission rates depending on the intensity of autofluorescence UV light (Leica DMI 6000, Mannheim, Germany) [ 79 ].…”

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

“…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 ). At present, 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 ).…”