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

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.

Characterization of rhizospheric bacteria isolated from soil cultivated with sugarcane in Tamaulipas state, Mexico

The state of Tamaulipas, Mexico, has two important sugar mills, with plantations of sugarcane (Saccharum officinarum L.) of more than 50 years, the objective of the study was the identification and bacterial characterization in the production of indole-3-acetic acid (IAA), the solubilization of phosphorus and plant growth of bacterial isolates from the rhizosphere of sugarcane. The isolation and morphological characterization were in 30 rhizosphere soil samples of the sugarcane variety CP 72-2086 using the Luria-Bertani media, Congo Red Agar and Potato Dextrose Agar. The molecular characterization was with the 16S rRNA gene and the bacterial inoculation consisted of seedlings of the variety CP 72-2086. 121 strains (38 species) were isolated, being Bacillus sp. most frequently, 14 species were positive for phosphorus solubilization: Bacillus sp. (6), Pseudomonas spp. (5), Paenibacillus (2) Streptomyces venezuelae (1) stand out. The greater phosphorus solubilization was Pseudomonas mediterranea (21.6 mm). Nine bacteria showed production close to 5 ppm IAA: Bacillus aryabhattai (6 ppm), Bacillus pumilus (5.8 ppm) and Ensifer adhaerens (5.6 ppm). Bacillus megaterium showed a higher percentage of chlorophyll and foliar nitrogen. In the present analysis, 38 bacterial species associated with the rhizosphere of the sugarcane variety CP 72-2086 were identified, so these results showed the potential to select native bacteria that have the ability to stimulate plant growth of the variety CP 72-2086.

Potassium application for sugarcane in a sandy loam Oxisol of the Brazilian Cerrado

The objective of this work was to evaluate rates and methods of potassium application for plant cane (Saccharum spp.) grown in a dystrophic Typic Haplustox with a sandy loam texture in the Brazilian Cerrado. The experiment was carried out in the municipality of Aporé, in the state of Goiás, using the RB92579 sugarcane variety. The experimental design was randomized complete blocks, with three replicates, in a 5x3 factorial arrangement, with five potassium rates (0, 60, 110, 160, and 200 kg ha-1 K2O as potassium chloride) and three application methods (100% at the bottom of the planting furrow and covered with soil, 100% side-dressed on the sugarcane rows 60 days after planting, and 50% in the planting furrow and 50% side-dressed). The amount of potassium in the stalks in the control treatment was greater than that of the potassium stock extractable by Mehlich-1 in the 0-60 cm soil layer. Stalk and sugar yields increase linearly with potassium rates, approximately 20% with 200 kg ha-1 K2O compared with the control treatment (without potassium). Potassium content in stalks also increases with potassium rates. There is no significant effect of the potassium application methods on stalk and sugar yields and on cane quality variables.

Productive Potential of Nitrogen and Zinc Fertigated Sugarcane

The relevance of sugarcane (Saccharum officinarum L.) in the agribusiness is irrefutable because it not only contributes greatly to the development of countries but is also an important source of job creation and income generation. The objective of this study was to evaluate the stalk productivity (SP) and sugar and alcohol yields of plant and ratoon crops of sugarcane (variety IACSP 95-5000) under N and Zn fertigation treatments using a central pivot, in Cerrado Red Latosol soil. The experiment was conducted under field conditions, in the municipality of Jataí, Goiás (GO), Brazil. A randomized block design was used, with a 4 × 5 split-plot arrangement and three replications. The fertilization treatments consisted of four doses of N (0, 60, 120, and 180 kg ha−1) and five doses of Zn (0, 2.5, 5.0, 7.5, and 10.0 kg ha−1) in plant and ratoon crops. N fertilization treatments, in the form of urea, were divided into three applications from 60 days after planting. Zn fertilization, in the form of Zn sulfate, was applied in a single application. Sugarcane was harvested 330 days after planting. The productivity (SP) was determined by weighing the stalks present in the respective subplots. Sugar and alcohol yields were calculated from the amount of raw sugar determined in the technological analysis. The sugar and alcohol yields of sugarcane (variety IACSP 95-5000) were improved with the fertigation of 180 kg ha−1 of N, in relation to Zn doses. Compared with the control (without N fertigation), sugarcane productivity (plant and ratoon crops) increased by 38.90% and 13.70% when treated with 180 kg ha−1 of N at the Zn dose of 10 kg ha−1. Sugarcane (variety IACSP 95-5000) has productive performance, sugar and alcohol yield, optimized and maximized when fertigated with 10 kg ha−1 of zinc and 180 kg ha−1 of nitrogen.