Molecular Soil Biology 2024, Vol.15, No.1, 28-36 http://bioscipublisher.com/index.php/msb 30 By leveraging the genetic diversity and high BNF capacity of wild sugarcane progenitors like Saccharum spontaneumL., it is possible to develop new sugarcane varieties that are more resilient and efficient in nitrogen utilization (Luo et al., 2023). 3 Mechanisms of Symbiotic Nitrogen Fixation in Sugarcane 3.1 Biological pathways and interactions between sugarcane and nitrogen-fixing bacteria The interaction between sugarcane and nitrogen-fixing bacteria involves complex biological pathways. Diazotrophic bacteria, such as Pseudomonas, Bacillus, and Enterobacter species, colonize the rhizosphere and endophytic tissues of sugarcane, facilitating nitrogen fixation (Singh et al., 2020). These bacteria possess the nifH gene, which encodes for the nitrogenase enzyme responsible for the conversion of atmospheric nitrogen to ammonia (Singh et al., 2021). The colonization of sugarcane roots by these bacteria leads to the formation of specialized structures and physiological modifications that enhance nitrogen uptake and assimilation (Lindström and Mousavi, 2019; Aasfar et al., 2021). 3.2 Genetic and molecular aspects of nitrogen fixation in sugarcane The genetic and molecular mechanisms underlying nitrogen fixation in sugarcane involve the regulation of various genes and metabolic pathways. Studies have shown that the expression of genes related to nitrogen metabolism, such as nifH, and stress-related genes, including those encoding for catalase, superoxide dismutase, and phenylalanine ammonia-lyase, are upregulated in sugarcane inoculated with nitrogen-fixing bacteria (Singh et al., 2020). Additionally, transcriptome analyses have revealed differential gene expression in sugarcane genotypes with varying BNF efficiencies, highlighting the role of auxin signaling and microorganism perception pathways in modulating nitrogen fixation (Carvalho et al., 2022; Luo et al., 2023). 3.3 Recent research findings on enhancing nitrogen fixation efficiency Recent research has focused on enhancing the efficiency of nitrogen fixation in sugarcane through the selection and inoculation of effective diazotrophic strains. For instance, the inoculation of sugarcane with Pseudomonas koreensis CY4 and Pseudomonas entomophila CN11 has been shown to significantly increase nitrogen fixation and plant growth under greenhouse conditions (Singh et al., 2023). Similarly, the use of Bacillus megateriumCY5 and Bacillus mycoides CA1 strains has demonstrated substantial improvements in nitrogen accumulation and pathogen resistance in sugarcane (Figure 1) (Singh et al., 2020). Furthermore, the identification of high-BNF sugarcane genotypes and the exploration of their genetic diversity offer promising avenues for developing nitrogen-efficient sugarcane varieties (Carvalho et al., 2022; Luo et al., 2023). Singh et al. (2020) displays fluorescence (GFP) micrographs of sugarcane plant parts (leaf, stem, and root) colonized by GFP-tagged Bacillus megaterium(CY5) and Bacillus mycoides (CA1), highlighting the interaction between the bacterial strains and the plant tissues. Control plant parts (A-C) show no bacterial colonization, while the inoculated plant parts (D-I) exhibit green fluorescence indicating the presence of GFP-tagged bacteria. The images reveal bacterial colonization on the surface of roots, junction areas, stems, and leaves, with blue arrowheads marking individual or clusters of bacterial cells. This study demonstrates the successful colonization of sugarcane by beneficial bacteria, potentially enhancing nutrient uptake and plant growth. The use of GFP tagging and confocal laser scanning microscopy effectively visualizes bacterial distribution within the plant, providing valuable insights into the symbiotic relationship and its implications for sustainable agriculture. This research underlines the potential of biofertilizers in reducing chemical fertilizer dependency and promoting healthier crop growth. 4 Technological Advancements in Symbiotic Nitrogen Fixation 4.1 Genetic engineering and biotechnology approaches Genetic engineering and biotechnology have significantly advanced our understanding and application of SNF in non-leguminous crops like sugarcane. Researchers have identified and manipulated key genes involved in nitrogen fixation, such as the nifH gene, which encodes a component of the nitrogenase enzyme complex responsible for converting atmospheric nitrogen into a bioavailable form (Guo et al., 2020; Singh et al., 2022). For
RkJQdWJsaXNoZXIy MjQ4ODYzMg==