Dataset Information

Identification of drought-response genes and a study of their expression during sucrose accumulation and water deficit in sugarcane culms.

ABSTRACT:

Background

The ability of sugarcane to accumulate high concentrations of sucrose in its culm requires adaptation to maintain cellular function under the high solute load. We have investigated the expression of 51 genes implicated in abiotic stress to determine their expression in the context of sucrose accumulation by studying mature and immature culm internodes of a high sucrose accumulating sugarcane cultivar. Using a sub-set of eight genes, expression was examined in mature internode tissues of sugarcane cultivars as well as ancestral and more widely related species with a range of sucrose contents. Expression of these genes was also analysed in internode tissue from a high sucrose cultivar undergoing water deficit stress to compare effects of sucrose accumulation and water deficit.

Results

A sub-set of stress-related genes that are potentially associated with sucrose accumulation in sugarcane culms was identified through correlation analysis, and these included genes encoding enzymes involved in amino acid metabolism, a sugar transporter and a transcription factor. Subsequent analysis of the expression of these stress-response genes in sugarcane plants that were under water deficit stress revealed a different transcriptional profile to that which correlated with sucrose accumulation. For example, genes with homology to late embryogenesis abundant-related proteins and dehydrin were strongly induced under water deficit but this did not correlate with sucrose content. The expression of genes encoding proline biosynthesis was associated with both sucrose accumulation and water deficit, but amino acid analysis indicated that proline was negatively correlated with sucrose concentration, and whilst total amino acid concentrations increased about seven-fold under water deficit, the relatively low concentration of proline suggested that it had no osmoprotectant role in sugarcane culms.

Conclusions

The results show that while there was a change in stress-related gene expression associated with sucrose accumulation, different mechanisms are responding to the stress induced by water deficit, because different genes had altered expression under water deficit.

SUBMITTER: Iskandar HM

PROVIDER: S-EPMC3030532 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Publications

Identification of drought-response genes and a study of their expression during sucrose accumulation and water deficit in sugarcane culms.

Iskandar Hayati M HM Casu Rosanne E RE Fletcher Andrew T AT Schmidt Susanne S Xu Jingsheng J Maclean Donald J DJ Manners John M JM Bonnett Graham D GD

BMC plant biology 20110113

<h4>Background</h4>The ability of sugarcane to accumulate high concentrations of sucrose in its culm requires adaptation to maintain cellular function under the high solute load. We have investigated the expression of 51 genes implicated in abiotic stress to determine their expression in the context of sucrose accumulation by studying mature and immature culm internodes of a high sucrose accumulating sugarcane cultivar. Using a sub-set of eight genes, expression was examined in mature internode ...[more]

PMID: 21226964

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Project description:BACKGROUND: Sucrose content is a highly desirable trait in sugarcane as the worldwide demand for cost-effective biofuels surges. Sugarcane cultivars differ in their capacity to accumulate sucrose and breeding programs routinely perform crosses to identify genotypes able to produce more sucrose. Sucrose content in the mature internodes reach around 20% of the culms dry weight. Genotypes in the populations reflect their genetic program and may display contrasting growth, development, and physiology, all of which affect carbohydrate metabolism. Few studies have profiled gene expression related to sugarcane's sugar content. The identification of signal transduction components and transcription factors that might regulate sugar accumulation is highly desirable if we are to improve this characteristic of sugarcane plants. RESULTS: We have evaluated thirty genotypes that have different Brix (sugar) levels and identified genes differentially expressed in internodes using cDNA microarrays. These genes were compared to existing gene expression data for sugarcane plants subjected to diverse stress and hormone treatments. The comparisons revealed a strong overlap between the drought and sucrose-content datasets and a limited overlap with ABA signaling. Genes associated with sucrose content were extensively validated by qRT-PCR, which highlighted several protein kinases and transcription factors that are likely to be regulators of sucrose accumulation. The data also indicate that aquaporins, as well as lignin biosynthesis and cell wall metabolism genes, are strongly related to sucrose accumulation. Moreover, sucrose-associated genes were shown to be directly responsive to short term sucrose stimuli, confirming their role in sugar-related pathways. CONCLUSION: Gene expression analysis of sugarcane populations contrasting for sucrose content indicated a possible overlap with drought and cell wall metabolism processes and suggested signaling and transcriptional regulators to be used as molecular markers in breeding programs. Transgenic research is necessary to further clarify the role of the genes and define targets useful for sugarcane improvement programs based on transgenic plants.

Project description:Sugarcane is an economically important crop contributing to the world’s sugar and ethanol production with 80% and 40%, respectively. In recent years, the growing demands for sugar and ethanol production has prompted the necessity to increase sugarcane productivity through conventional breeding programs. However, sugarcane breeders have encountered several difficulties to raise productivity, mainly due to its complex genetics. Sugarcane has a polyploidy genome, with many varieties being aneuploidy. Today, the majority of the planted sugarcane cultivars are complex hybrids derived mainly from crosses between Saccharum officinarum and S. spontaneum. Therefore, proteomics can provide some insight into deciphering gene regulation and changes in carbon metabolism and sucrose accumulation in the culms at different stages of plant development. The aim of this work was to compare the quantitative changes of proteins in sugarcane culms, during plant growth and sucrose accumulation. Total proteins were isolated from both, juvenile and maturing internodes at three stages of plant development. Label free shotgun proteomics was used for protein profiling and quantification. The internodes 5 (I5) and 9 (I9) of 4, 7 and 10 month-old-plants (4M, 7M and 10M, respectively) were harvested and used for proteomic analyses. To mimic field conditions of sucrose accumulation during sugarcane maturation, we stopped watering 10M plants for 10 days. An average of 1130 proteins, unique and differentially expressed across all ages were identified and quantified. Proteins were categorized within 27 functional groups, related to biological process. The patterns of expression for some categories, such as cellular amino acids, metabolic processes, secondary metabolic processes and translation were down-regulated in the immature internode (I5-10M), while up-regulated in the mature I9-10M. We observed an increase in the abundance of several enzymes of the glycolytic pathway and isoforms of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC), in the juvenile stages of development of I9. These changes in enzymes contents indicates that at the early stages of internode development, hypoxia is increasing the glycolytic and ethanolic fermentation pathways, in order to supply ATP for plant growth and NAD+ for mitochondrial respiration, which might be impaired by the low oxygen availability inside the culm.

Dataset Information

Identification of drought-response genes and a study of their expression during sucrose accumulation and water deficit in sugarcane culms.

Background

Results

Conclusions

Publications

Identification of drought-response genes and a study of their expression during sucrose accumulation and water deficit in sugarcane culms.

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