Signal transduction-related responses to phytohormones and environmental challenges in sugarcane

Abstract

BackgroundSugarcane is an increasingly economically and environmentally important C4 grass, used for the production of sugar and bioethanol, a low-carbon emission fuel. Sugarcane originated from crosses of Saccharum species and is noted for its unique capacity to accumulate high amounts of sucrose in its stems. Environmental stresses limit enormously sugarcane productivity worldwide. To investigate transcriptome changes in response to environmental inputs that alter yield we used cDNA microarrays to profile expression of 1,545 genes in plants submitted to drought, phosphate starvation, herbivory and N2-fixing endophytic bacteria. We also investigated the response to phytohormones (abscisic acid and methyl jasmonate). The arrayed elements correspond mostly to genes involved in signal transduction, hormone biosynthesis, transcription factors, novel genes and genes corresponding to unknown proteins.ResultsAdopting an outliers searching method 179 genes with strikingly different expression levels were identified as differentially expressed in at least one of the treatments analysed. Self Organizing Maps were used to cluster the expression profiles of 695 genes that showed a highly correlated expression pattern among replicates. The expression data for 22 genes was evaluated for 36 experimental data points by quantitative RT-PCR indicating a validation rate of 80.5% using three biological experimental replicates. The SUCAST Database was created that provides public access to the data described in this work, linked to tissue expression profiling and the SUCAST gene category and sequence analysis. The SUCAST database also includes a categorization of the sugarcane kinome based on a phylogenetic grouping that included 182 undefined kinases.ConclusionAn extensive study on the sugarcane transcriptome was performed. Sugarcane genes responsive to phytohormones and to challenges sugarcane commonly deals with in the field were identified. Additionally, the protein kinases were annotated based on a phylogenetic approach. The experimental design and statistical analysis applied proved robust to unravel genes associated with a diverse array of conditions attributing novel functions to previously unknown or undefined genes. The data consolidated in the SUCAST database resource can guide further studies and be useful for the development of improved sugarcane varieties.

Expression Profile of Signal Transduction Components in a Sugarcane Population Segregating for Sugar Content

“…In plants, SNF1-related kinases have been named SnRK1 [14] and comprise three distinct sub-families (SnRK1, SnRK2 and SnRK3). Members of all three sub-families were identified in sugarcane [48]. Studies led to the hypothesis that once SnRK1 is activated in response to high intracellular sucrose and/or low intracellular glucose levels, SnRK1 can phosphorylate plant enzymes and activate starch synthesis in potato tubers [16,44].…”

“…It is interesting to note that eight stress-related genes were upregulated in the LS plants. Most of them are cold and drought-induced and they were also previously identified in association with sucrose content in sugarcane internodes [37,38,48].…”

Caracterização de promotores de expressão especifica de cana-de-açucar (Saccharum ssp.) em sistema modelo Micro-Tom (Solanum lycopersicum L)

“…As plantas reagem a alterações ambientais através de uma variedade de respostas celulares, causando alterações fisiológicas que podem ser moduladas por regulação da transcrição para a indução ou repressão de genes, levando a mudanças morfológicas, fisiológicas, bioquímicas e moleculares, afetando adversamente o crescimento e desenvolvimento vegetal (SCHENK et al, 2000;WANG et al, 2001;ROCHA et al, 2007).…”

“…O ataque de insetos-praga a partes aéreas e/ou sistema radicular das plantas, prejudica a produtividade da cana, reduzindo a eficiência econômica de produção tanto para a indústria do açúcar como do álcool (ROCHA et al, 2007). Entre as pragas, a principal é a broca da cana (Diatraea saccharalis), cujas larvas danificam a planta de cana perfurando o colmo, onde empupam e de onde os adultos emergem (WHITE et al, 2001;SILVA, 2008).…”

“…Rushton et al (2002) Considerando que as cascatas de sinalização em resposta a ataque de agentes bióticos, insetos-praga, o uso de promotores sintéticos é uma abordagem relevante para amplificação do sinal de ataque de insetos-praga (RUSHTON et al, 2002;HEIL, 2009). No entanto, a caracterização de regiões promotoras, assim como a introdução de genes exógenos em plantas (transgenia), requer o estabelecimento de técnicas de transformação genética e regeneração de plantas altamente eficientes, associados a avanços nos sistemas de manipulação de genes (ROCHA et al, 2007).…”