Project description:Sugarcane established industrial crop providing sugar, ethanol and biomass-derived electricity around the world. Cane sugar content is an important, breeding target, but its improvement remains very slow in many breeding programmes. Biotechnology strategies to improve sucrose accumulation made little progress at crop level, mainly due to the limited understanding of its regulation. MiRNAs regulate many metabolic processes in plants. However, their roles and target genes associated with sugarcane sucrose accumulation remains unknown. Here, we conducted high-throughput sequencing of transcriptome, small RNAs and degradome of leaves and stem of two sugarcane genotypes with contrasting sucrose content from the early to late stages of sucrose accumulation stages, which provided more insights into miRNA-associated gene regulation during sucrose accumulation. Transcriptome analysis identified 18,722 differentially expressed genes (DEGs) between both genotypes during sucrose accumulation. The major DEGs identified were involved in starch and sucrose metabolism, and photosynthesis etc. miRNA sequencing identified 563 known and 281 novel miRNAs from both genotypes during sucrose accumulation. Of these, 311 miRNAs were differentially expressed.752 targets of 368 miRNAs (609 targets for 260 known miRNAs and 168 targets for 108 novel miRNAs) were identified by degradom sequencing.Several known and novel miRNAs and their target genes associated with sugar metabolism, sugar transport and sucrose storage were identified in this study.This new insight into the complex network of sucrose accumulation in sugarcane will help identify candidate targets for sucrose improvement in sugarcane through molecular means.
Project description:Background: Sugarcane is an important sugar and energy crop largely used for bioethanol production in the world. The development of sugarcane cultivars with high sucrose content and yield is one of the biggest challenges of breeding programs nowadays. To identify genes networks that underlie sucrose content and yield, we used a custom designed oligonucleotide array with 21,901 different probes to study the transcriptome from breeding populations of sugarcane contrasting to sucrose content and genotypes contrasting to photosynthesis rate. Results: Physiological and biochemical data reveals that the transcriptome profiles described here showed a close relationship between sucrose content and stem development. A total of 2135 genes were differentially expressed in at least one experimental hybridization. We identified genes related to carbohydrate metabolism, cell wall metabolism and signal transduction. The same oligoarrays was used to detect transcription in both sense and antisense orientation. The enriched functional category from antisense expressed genes reveals light harvesting and circadian clock as the two top categories that can be related to photosynthesis and yield in sugarcane. Conclusions: Knowledge on the mechanisms underlying carbon partitioning and its relationship with sucrose accumulation in sugarcane stems would help defines routes to increase yield. Our findings showed for instance that sucrose accumulation and yield in sugarcane may be regulated by hormone signaling pathways, light harvesting and circadian clock genes. Analysis of the expression data and gene category enrichment provided an insight into signaling pathways and transcriptional control contrasting in high brix and low brix plants as well as differing photosynthesis rates and yield.
Project description:The rate of improvement of sugar content in sugarcane remains low for decades worldwide. Our previous transcriptome studies provided an atlas of sucrose accumulation-related gene expression but little is known about proteins involved. Here this knowledge gap is addressed by a proteomic analysis of experimentally altered sucrose accumulation in sugarcane. Analysis of stem proteomes of ripener ethephon-treated high- and low-sugar genotypes had identified 2983 proteins of which 139 were significantly differentially expressed (DEPs). These DEPs were found to be involved in sugar metabolism-related processes with 25 of them may have a regulatory role in sucrose accumulation. The key proteins identified include UDP-glucose 6-dehydrogenase associated with amino sugar and nucleotide sugar metabolism; those involved in carbon fixation; and fructokinase, β-D-glucosidase and α-glucan phosphorylase involved in starch and sucrose metabolism. Distinct genotype- and ethephon-dependent DEP expression was evident providing new insights on one of the most intractable sugarcane traits to breeding.
Project description:Comparatively transcriptomic analysis revealed outperforming photosynthesis, water retention, and stress responding gene expressions of a sugarcane providing high yield under drought
Project description:Sugarcane accumulates high concentrations of sucrose in the mature stalk, with numerous physiological processes in maturing stalk tissue both directly and indirectly involved. A considerable portion of carbohydrate metabolism is also devoted to cell wall synthesis and fibre production. Previously, we have identified differentially expressed transcripts correlated with sucrose accumulation and fibre production in various internodes of the sugarcane stalk. In this study, we have examined tissue-specific expression patterns to further explore gene pathways responsible for sucrose accumulation and fibre synthesis. We performed large-scale expression profiling of storage parenchyma, vascular bundles and rind dissected from a maturing stalk internode from field-grown commercial sugarcane harvested at 11 months of age. We identified 10 cellulose synthase subunit genes in sugarcane and examined significant differences in the expression of their corresponding transcripts and those of several sugar transporters between the different tissues. These were further correlated with differential expression patterns for transcripts of specific COBRA-like proteins and other proteins with acknowledged roles in cell wall metabolism. We found that the sugar transporters ShPST2a, ShPST2b and ShSUT4 were significantly up-regulated in storage parenchyma while ShSUT1 was up-regulated in vascular bundles. Two co-ordinately expressed groups of cell wall related transcripts were also identified. One group which is associated with primary cell wall synthesis (ShCesA1, ShCesA7, ShCesA9 and Shbk2l3) was up-regulated in parenchyma. The other group which is associated with secondary cell wall synthesis (ShCesA10, ShCesA11, ShCesA12 and Shbk-2) was up-regulated in rind. We also report an unexpected paucity in differential expression of cell wall-related genes in vascular bundles. Our results indicate that there is spatial separation for elevated expression of these important targets in both sucrose accumulation and cell wall synthesis, allowing for increased clarity in our understanding of sucrose transport and fibre synthesis in sugarcane.