Assembly and comparative genome analysis of four mitochondrial genomes from Saccharum complex species.

Saccharum complex includes genera Saccharum, Miscanthus, Erianthus, Narenga, and Tripidium. Since the Saccharum complex/Saccharinae constitutes the gene pool used by sugarcane breeders to introduce useful traits into sugarcane, studying the genomic characterization of the Saccharum complex has become particularly important. Here, we assembled graph-based mitochondrial genomes (mitogenomes) of four Saccharinae species (T. arundinaceum, E. rockii, M. sinensis, and N. porphyrocoma) using Illumina and PacBio sequencing data. The total lengths of the mitogenomes of T. arundinaceum, M. sinensis, E. rockii and N. porphyrocoma were 549,593 bp, 514,248 bp, 481,576 bp and 513,095 bp, respectively. Then, we performed a comparative mitogenomes analysis of Saccharinae species, including characterization, organelles transfer sequence, collinear sequence, phylogenetics analysis, and gene duplicated/loss. Our results provided the mitogenomes of four species closely related to sugarcane breeding, enriching the mitochondrial genomic resources of the Saccharinae. Additionally, our study offered new insights into the evolution of mitogenomes at the family and genus levels and enhanced our understanding of organelle evolution in the highly polyploid Saccharum genus.

Metabolic and proteomic analysis of nitrogen metabolism mechanisms involved in the sugarcane - Fusarium verticillioides interaction.

Pokkah boeng disease (PBD) is a foliar disease causing severe losses in sugarcane crop production. Research into resistance mechanisms against the causal agent, Fusarium verticillioides, is particularly important for farmers and researchers. This work based on the comprehensive analysis of metabolic, proteomic, and bioinformatics data on nitrogen (N) metabolism, which revealed that this biosynthetic reactions was closely related to resistance mechanisms in the sugarcane- F. verticillioides interaction. Our results suggested that pathogen infection reduced the suppression of nitrate reductase (NR) activity, reducing ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) assimilation, which reduces glutamine synthetase (GS), glutamate synthetase (GOGAT) activity and polynucleotide synthesis and promotes RNA degradation, resulting in a decrease in ribosome levels and protein synthesis. Cysteine was found to be associated with the symptoms of PBD, while alanine, lysine, proline, and glutamic acid were found to be involved in protective and regulatory mechanisms as well. Additionally, glutamate played an important role in sugarcane defense against pathogens through the biosynthesis of proline and polyamines. Cyanamide, glutamate, proline, tyrosine, and arachidonic acid metabolism actively participate in resistance and response to stress. C5XPZ6 and C5XCA6 were considered to be critical proteins and key effectors according to this study. In conclusion, we have identified potential proteins and pathways involved in sugarcane resistance to F. verticillioides, revealing new findings that may be useful in the design of future diagnostics or sugarcane protection strategies and providing new insights into the molecular mechanisms of sugarcane-pathogen interactions.