Sugarcane, a vital cash crop, contributes significantly to the world’s sugar supply and raw materials for biofuel production, playing a significant role in the global sugar industry. However, sustainable productivity is severely hampered by biotic and abiotic stressors. Genetic engineering has been used to transfer useful genes into sugarcane plants to improve desirable traits and has emerged as a basic and applied research method to maintain growth and productivity under different adverse environmental conditions. However, the use of transgenic approaches remains contentious and requires rigorous experimental methods to address biosafety challenges. Clustered regularly interspaced short palindromic repeat (CRISPR) mediated genome editing technology is growing rapidly and may revolutionize sugarcane production. This review aims to explore innovative genetic engineering techniques and their successful application in developing sugarcane cultivars with enhanced resistance to biotic and abiotic stresses to produce superior sugarcane cultivars.
Sugars transported from leaves (source) to stems (sink) energize cell growth, elongation, and maintenance. which are regulated by a variety of genes. This review reflects progress and prospects in the regulatory mechanism for maximum sucrose accumulation, including the role of sucrose metabolizing enzymes, sugar transporters and the elucidation of post-transcriptional control of sucrose-induced regulation of translation (SIRT) in the accumulation of sucrose. The current review suggests that SIRT is emerging as a significant mechanism controlling Scbzip44 activities in response to endogenous sugar signals (via the negative feedback mechanism). Sucrose-controlled upstream open reading frame (SC-uORF) exists at the 5′ leader region of Scbzip44's main ORF, which inhibits sucrose accumulation through post-transcriptional regulatory mechanisms. Sucrose transporters (SWEET1a/4a/4b/13c, TST, SUT1, SUT4 and SUT5) are crucial for sucrose translocation from source to sink. Particularly, SWEET13c was found to be a major contributor to the efflux in the transportation of stems. Tonoplast sugar transporters (TSTs), which import sucrose into the vacuole, suggest their tissue-specific role from source to sink. Sucrose cleavage has generally been linked with invertase isozymes, whereas sucrose synthase (SuSy)-catalyzed metabolism has been associated with biosynthetic processes such as UDP-Glc, cellulose, hemicellulose and other polymers. However, other two key sucrose-metabolizing enzymes, such as sucrose-6-phosphate phosphohydrolase (S6PP) and sucrose phosphate synthase (SPS) isoforms, have been linked with sucrose biosynthesis. These findings suggest that manipulation of genes, such as overexpression of SPS genes and sucrose transporter genes, silencing of the SC-uORF of Scbzip44 (removing the 5′ leader region of the main ORF that is called SIRT-Insensitive) and downregulation of the invertase genes, may lead to maximum sucrose accumulation. This review provides an overview of sugarcane sucrose-regulating systems and baseline information for the development of cultivars with higher sucrose accumulation.
1 December 2020 in Research in Astronomy and Astrophysics
Thanks to more and more gamma-ray bursts with measured redshift and extended emission detected by the recent space telescopes, it is urgent and possible to check whether those previous energy correlations still satisfy the particular sample involving only the bursts accompanied by tail radiations. Using 20 long and 22 short bursts with extended emission, we find that the popular γ -ray energy correlations of the intrinsic peak energy versus the isotropic energy (Amati relation) and the intrinsic peak energy versus the peak luminosity (Yonetoku relation) do exist in both short and long bursts. However, it is much better if these gamma-ray bursts with extended emissions are reclassified into two subgroups of E-I and E-II that make the above energy correlations more tight. As proposed by Zhang et al., the energy correlations can be utilized to distinguish these kinds of gamma-ray bursts in the plane of bolometric fluence versus peak energy as well. Interestingly, the peculiar short GRB 170817A belongs to the E-I group in the fluence versus peak energy plane, but it is an outlier of both the Amati and Yonetoku relations even though the off-axis effect has been corrected. Furthermore, we compare the radiation features between the extended emissions and the prompt gamma-rays in order to search for their possible connections. Taking into account all these factors, we conclude that gamma-ray bursts with extended emission are still required to model with dichotomic groups, namely E-I and E-II classes, which hint that they might have different origins.
Sugarcane, a key cash crop in tropical and subtropical regions, is primarily cultivated for sucrose and bioethanol. However, Sugarcane Leaf Scald Disease, caused by the Gram-negative bacterium Xanthomonas albilineans, significantly threatens global sugarcane production. This review examines the disease cycle, epidemics, host–pathogen interactions, integrated management strategies, and future prospects for combating leaf scald. It highlights advancements in understanding pathogenicity, immune responses, and sustainable management of bacterial plant diseases to enhance control and prevention efforts. An analysis of GenBank data revealed 21 strains of X. albilineans, with some featuring complete genome maps and varying guanine-cytosine (GC) content. Advanced genomic tools, including clustered regularly interspaced short palindromic repeats (CRISPR), and molecular techniques, such as polymerase chain reaction (PCR), enable accurate pathogen detection and facilitate the identification of resistance genes, aiding breeding programs. Recent progress in whole-genome sequencing and reduced costs have enabled the assembly of multiple X. albilineans genomes, enhancing bioinformatics analysis. Despite these advancements, research on the global genetic diversity of X. albilineans remains limited. Addressing this gap is crucial for developing more sustainable strategies to manage leaf scald, ensuring stable sugarcane yields and supporting global production. Further studies will strengthen efforts to mitigate this significant agricultural challenge.
1 December 2022 in Plant Genetic Resources: Characterization and Utilization
Germplasm innovation can provide materials for breeding sugarcane cultivars. Saccharum officinarum is the main source of high-sugar and high-yield genes in sugarcane breeding. ‘Nobilization’ is the theoretical basis for exploiting S. officinarum, and S. officinarum authenticity directly affects sugarcane nobility breeding efficiency. Herein, the authenticity of 22 SLC-series S. officinarum clones imported from Sri Lanka and preserved in the China National Germplasm Repository of Sugarcane (NGRS) was explored by four-primer amplification-arrested mutation PCR (ARMS PCR) and somatic chromosome number counting. The amplified bands from SLC 08 120 and SLC 08 131 were the same with those from S. officinarum clone Badila, i.e. a common band of 428 bp and a S. officinarum-specific band of 278 bp, hence they were tentatively assigned as S. officinarum clones. The other 20 SLC clones had both 278 bp (S. officinarum-specific) and 203 bp (S. spontaneum-specific) bands, which are hybrid characteristics. In addition, the chromosome numbers of SLC 08 120 and SLC 08 131 are both 80, belong to typical S. officinarum. While the chromosome numbers of the other 20 materials are ranging from 101 to 129, consistent with hybrids of S. officinarum and S. spontaneum. This molecular cytological characterization indicates that among the 22 introduced SLC-series clones, only two, SLC 08 120 and SLC 08 131, were S. officinarum. Future agronomic trait and resistance analyses could facilitate their use as crossing parents in sugarcane breeding.
Fructose-1,6-bisphosphatase (FBP) is a crucial regulatory enzyme in sucrose synthesis and photosynthetic carbon assimilation, functioning through two distinct isoforms: cytosolic FBP (cyFBP) and chloroplastic FBP (cpFBP). However, the identification and functional characterization of FBP genes in Saccharum remains limited. In this study, we conducted a systematic identification and comparative genomics analyses of FBPs in three Saccharum species. We further examined their expression patterns across leaf developmental zones, spatiotemporal profiles, and responses to diurnal rhythms and hormonal treatments. Our analysis identified 95 FBP genes, including 44 cyFBPs and 51 cpFBPs. Comparative analyses revealed significant divergence in physicochemical properties, gene structures, and motif compositions between the two isoforms. Expression profiling indicated that both cyFBPs and cpFBPs were predominantly expressed in leaves, particularly in maturing and mature zones. During diurnal cycles, their expression peaked around the night–day transition, with cpFBPs exhibiting earlier peaks than cyFBPs. FBP genes in Saccharum spontaneum displayed greater diurnal sensitivity than those in Saccharum officinarum. Hormonal treatments further revealed significant regulatory divergence in FBP genes, both between isoforms and across species. Notably, cyFBP_2 and cpFBP_2 members consistently exhibited higher expression levels across all datasets, suggesting their pivotal roles in sugarcane physiology. These findings not only identify potential target genes for enhancing sucrose accumulation, but also highlight the breeding value of S. spontaneum and S. officinarum in sugarcane breeding.