Leaf scald, caused by Xanthomonas albilineans, is a severe disease affecting sugarcane worldwide. One of the most practical ways to control it is by developing resistant sugarcane cultivars. It is essential to identify genes associated with the response to leaf scald. A panel of 170 sugarcane genotypes was evaluated for resistance to leaf scald in field conditions for 2 years, followed by a 1-year greenhouse experiment. The phenotypic evaluation data showed a wide continuous distribution, with heritability values ranging from 0.58 to 0.84. Thirteen single nucleotide polymorphisms (SNPs) were identified, significantly associated with leaf scald resistance. Among these, eight were stable across multiple environments and association models. The candidate genes identified and validated based on RNA-seq and qRT-PCR included two genes that encode NB-ARC leucine-rich repeat (LRR)-containing domain disease-resistance protein. These findings provide a basis for developing marker-assisted selection strategies in sugarcane breeding programs.

This study aimed to assess the effectiveness of urban derived biochars such as Sugarcane bagasse (SB), Brinjal Stem (BS), and Citrus Peel (CP) produced at two different pyrolysis conditions (450 and 600 °C for 60 min) for soil heavy metal bioremediation potential. An ex-situ study was conducted to remediate single heavy metal-contaminated SoilRite with lead (Pb), copper (Cu), chromium (Cr) and cadmium (Cd), with biochars applied at different rates. Heavy metal status in soilrite was evaluated using various extraction methods (water-soluble, exchangeable, TCLP (Toxicity Characteristic Leaching Procedure), and PBET (Physiologically Based Extraction Tests)) to determine the biochar treatments\' efficacy. The findings show that SB biochar at 450-60 are more effective in immobilizing heavy metals in water-soluble (Cd-100% Pb and Cu-70%), exchangeable (Pb:91%, Cd and Cu by 70-80%) and PBET-extracted forms (Cd-91%, Pb-80%, and Cu-75%), whereas biochar derived from BS (84%) and CP (90%) at 600-60 are more effective in immobilizing TCLP-extracted form of Pb and Cu. Urban derived biochars significantly reduced the toxicity of Pb, Cu, and Cd in various extractable forms and can stabilize and convert them into less accessible forms except for Cr. These extraction methods aid in evaluating environmental risks and influencing remediation strategies for soil heavy metal pollution. Urban biochar, as a cost-effective and eco-friendly solution, significantly solves this issue, facilitating sustainable waste management.

The auxin/indoleacetic acid (Aux/IAA) family plays a central role in regulating gene expression during auxin signal transduction. Nonetheless, there is limited knowledge regarding this gene family in sugarcane. In this study, 92 members of the IAA family were identified in Saccharum spontaneum, distributed on 32 chromosomes, and classified into three clusters based on phylogeny and motif compositions. Segmental duplication and recombination events contributed largely to the expansion of this superfamily. Additionally, cis-acting elements in the promoters of SsIAAs involved in plant hormone regulation and stress responsiveness were predicted. Transcriptomics data revealed that most SsIAA expressions were significantly higher in stems and basal parts of leaves, and at nighttime, suggesting that these genes might be involved in sugar transport. QRT-PCR assays confirmed that cold and salt stress significantly induced four and five SsIAAs, respectively. GFP-subcellular localization showed that SsIAA23 and SsIAA12a were localized in the nucleus, consistent with the results of bioinformatics analysis. In conclusion, to a certain extent, the functional redundancy of family members caused by the expansion of the sugarcane IAA gene family is related to stress resistance and regeneration of sugarcane as a perennial crop. This study reveals the gene evolution and function of the SsIAA gene family in sugarcane, laying the foundation for further research on its mode of action.

Bacteria within the Paenibacillus genus are known to secrete a diverse array of enzymes capable of breaking down plant cell wall polysaccharides. We studied the extracellular xylanolytic activity of Paenibacillus xylanivorans and examined the complete range of secreted proteins when grown on carbohydrate-based carbon sources of increasing complexity, including wheat bran, sugar cane straw, beechwood xylan and sucrose, as control. Our data showed that the relative abundances of secreted proteins varied depending on the carbon source used. Extracellular enzymatic extracts from wheat bran (WB) or sugar cane straw (SCR) cultures had the highest xylanolytic activity, coincidently with the largest representation of carbohydrate active enzymes (CAZymes). Scaling-up to a benchtop bioreactor using WB resulted in a significant enhancement in productivity and in the overall volumetric extracellular xylanase activity, that was further concentrated by freeze-drying. The enzymatic extract was efficient in the deconstruction of xylans from different sources as well as sugar cane straw pretreated by alkali extrusion (SCRe), resulting in xylobiose and xylose, as primary products. The overall yield of xylose released from SCRe was improved by supplementing the enzymatic extract with a recombinant GH43 β-xylosidase (EcXyl43) and a GH62 α-L-arabinofuranosidase (CsAbf62A), two activities that were under-represented. Overall, we showed that the extracellular enzymatic extract from P. xylanivorans, supplemented with specific enzymatic activities, is an effective approach for targeting xylan within lignocellulosic biomass.

CONCLUSIONS: We reported the graph-based mitochondrial genomes of three foundation species (Saccharum spontaneum, S. robustum and S. officinarum) for the first time. The results revealed pan-structural variation and evolutionary processes in the mitochondrial genomes within Saccharum. Saccharum belongs to the Andropogoneae, and cultivars species in Saccharum contribute nearly 80% of sugar production in the world. To explore the genomic studies in Saccharum, we assembled 15 complete mitochondrial genomes (mitogenome) of three foundation species (Saccharum spontaneum, S. robustum and S. officinarum) using Illumina and Oxford Nanopore Technologies sequencing data. The mitogenomes of the three species were divided into a total of eight types based on contig numbers and linkages. All mitogenomes in the three species encoded 51 unique genes, including 32 protein-coding, 3 ribosomal RNA (rRNA) and 16 transfer RNA (tRNA) genes. The existence of long and short-repeat-mediated recombinations in the mitogenome of S. officinarum and S. robustum was revealed and confirmed through PCR validation. Furthermore, employing comparative genomics and phylogenetic analyses of the organelle genomes, we unveiled the evolutionary relationships and history of the major interspecific lineages in Saccharum genus. Phylogenetic analyses of homologous fragments between S. officinarum and S. robustum showed that S. officinarum and S. robustum are phylogenetically distinct and that they were likely parallel rather than domesticated. The variations between ancient (S. sinense and S. barberi) and modern cultivated species (S. hybrid) possibly resulted from hybridization involving different S. officinarum accessions. Lastly, this project reported the first graph-based mitogenomes of three Saccharum species, and a systematic comparison of the structural organization, evolutionary processes, and pan-structural variation of the Saccharum mitogenomes revealed the differential features of the Saccharum mitogenomes.

Sugarcane is a central crop for sugar and ethanol production. Investing in sustainable practices can enhance productivity, technological quality, mitigate impacts, and contribute to a cleaner energy future. Among the factors that help increase the productivity of sugarcane, the physical, chemical and biological parameters of the soil are amongst the most important. The use of poultry litter has been an important alternative for soil improvement, as it acts as a soil conditioner. Therefore, this work aimed to verify the best doses of poultry litter for the vegetative, reproductive and technological components of sugarcane. The experiment was carried out at Usina Denusa Destilaria Nova União S/A in the municipality of Jandaia, GO. The experimental design used was a complete randomized block design with four replications: 5 × 4, totaling 20 experimental units. The evaluated factor consisted of four doses of poultry litter plus the control (0 (control), 2, 4, 6 and 8 t ha-1). In this study, were evaluated the number of tillers, lower stem diameter, average stem diameter, upper stem diameter, plant height, stem weight and productivity. The technological variables of total recoverable sugar, recoverable sugar, Brix, fiber, purity and percentage of oligosaccharides were also evaluated. It was observed, within the conditions of this experiment, that the insertion of poultry litter did not interfere significantly in most biometric, productive and technological variables of the sugarcane. But it can also be inferred that there was a statistical trend toward better results when the sugarcane was cultivated with 4 t ha-1 of poultry litter.

Plant resistance against biotic stressors is significantly influenced by pathogenesis-related 1 (PR1) proteins. This study examines the systematic identification and characterization of PR1 family genes in sugarcane (Saccharum spontaneum Np-X) and the transcript expression of selected genes in two sugarcane cultivars (ROC22 and Zhongtang3) in response to Ustilago scitaminea pathogen infection. A total of 18 SsnpPR1 genes were identified at the whole-genome level and further categorized into four groups. Notably, tandem and segmental duplication occurrences were detected in one and five SsnpPR1 gene pairs, respectively. The SsnpPR1 genes exhibited diverse physio-chemical attributes and variations in introns/exons and conserved motifs. Notably, four SsnpPR1 (SsnpPR1.02/05/09/19) proteins displayed a strong protein-protein interaction network. The transcript expression of three SsnpPR1 (SsnpPR1.04/06/09) genes was upregulated by 1.2-2.6 folds in the resistant cultivar (Zhongtang3) but downregulated in the susceptible cultivar (ROC22) across different time points as compared to the control in response to pathogen infection. Additionally, SsnpPR1.11 was specifically upregulated by 1.2-3.5 folds at 24-72 h post inoculation (hpi) in ROC22, suggesting that this gene may play an important negative regulatory role in defense responses to pathogen infection. The genetic improvement of sugarcane can be facilitated by our results, which also establish the basis for additional functional characterization of SsnpPR1 genes in response to pathogenic stress.

Over two decades, the area with sugarcane has more than doubled, from 4.8 million hectares in 2000 to 10 million in 2018, in Brazil. São Paulo State is mostly responsible for the sugarcane production in the country, accounting for 51% of the national production. In 2008, a study was conducted analysing the relationship between sugarcane cultivation and the aquatic macroinvertebrate community, showing the impacts of sugarcane on the macroinvertebrate aquatic fauna. The present study aims to gather actual information on the aquatic macroinvertebrate community in the same streams studied in 2008, to make a historical comparison with studies previously carried out. Eight streams were selected; four located in areas of sugarcane cultivation and four located in preserved areas. Three samples were carried out between 2018 and 2020. The aquatic macroinvertebrates were collected using a D-frame aquatic net (250 μm) including riffle and pools areas and identified using specific identification keys. The results of the historical assessment showed better ecological conditions of the streams in 2008 when compared to 2018 in areas of sugarcane cultivation, suggesting that the environmental impact was maintained and increased after ten years.

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Sugarcane smut is the most damaging disease that is present almost across the globe, causing mild to severe yield losses depending upon the cultivar types, pathogen races and climatic conditions. Cultivation of smut-resistant cultivars is the most feasible and economical option to mitigate its damages. Previous investigations revealed that there is a scarcity of information on early detection and effective strategies to suppress etiological agents of smut disease due to the characteristics overlapping within species complexes. In this study, 104 sugarcane cultivars were screened by artificial inoculation with homogenate of all possible pathogen races of Sporisorium scitamineum during two consecutive growing seasons. The logistic smut growth pattern and the disease intrinsic rate were recorded by disease growth curve. Variable levels of disease incidence i.e., ranging from 0 to 54.10% were observed among these sugarcane cultivars. Besides, pathogen DNA in plant shoots of all the cultivars was successfully amplified by PCR method using smut-specific primers except 26 cultivars which showed an immune reaction in the field trial. Furthermore, the plant germination and tillering of susceptible sugarcane cultivars were greatly influenced by pathogen inoculation. In susceptible cultivars, S. scitamineum caused a significant reduction in setts germination, coupled with profuse tillering, resulting in fewer millable canes. Correlation analysis demonstrated that there was a positive relationship between reduction in setts germination and increase in the number of tillers. The present study would be helpful for the evaluation of smut resistance in a wide range of sugarcane germplasm, especially from the aspects of setts germination and tillers formation, and it also screened out several excellent germplasm for potential application in sugarcane breeding.