A Novel Stress-induced Sugarcane Gene Confers Tolerance To Drought, Salt And Oxidative Stress In Transgenic Tobacco Plants.

Drought is a major abiotic stress that affects crop productivity worldwide. Sugarcane can withstand periods of water scarcity during the final stage of culm maturation, during which sucrose accumulation occurs. Meanwhile, prolonged periods of drought can cause severe plant losses. In a previous study, we evaluated the transcriptome of drought-stressed plants to better understand sugarcane responses to drought. Among the up-regulated genes was Scdr1 (sugarcane drought-responsive 1). The aim of the research reported here was to characterize this gene. Scdr1 encodes a putative protein containing 248 amino acids with a large number of proline (19%) and cysteine (13%) residues. Phylogenetic analysis showed that ScDR1is in a clade with homologs from other monocotyledonous plants, separate from those of dicotyledonous plants. The expression of Scdr1 in different varieties of sugarcane plants has not shown a clear association with drought tolerance. The overexpression of Scdr1 in transgenic tobacco plants increased their tolerance to drought, salinity and oxidative stress, as demonstrated by increased photosynthesis, water content, biomass, germination rate, chlorophyll content and reduced accumulation of ROS. Physiological parameters, such as transpiration rate (E), net photosynthesis (A), stomatal conductance (gs) and internal leaf CO(2) concentration, were less affected by abiotic stresses in transgenic Scdr1 plants compared with wild-type plants. Overall, our results indicated that Scdr1 conferred tolerance to multiple abiotic stresses, highlighting the potential of this gene for biotechnological applications.7e4469

A Novel Stress-Induced Sugarcane Gene Confers Tolerance to Drought, Salt and Oxidative Stress in Transgenic Tobacco Plants

Background: Drought is a major abiotic stress that affects crop productivity worldwide. Sugarcane can withstand periods of water scarcity during the final stage of culm maturation, during which sucrose accumulation occurs. Meanwhile, prolonged periods of drought can cause severe plant losses. Methodology/Principal Findings: In a previous study, we evaluated the transcriptome of drought-stressed plants to better understand sugarcane responses to drought. Among the up-regulated genes was Scdr1 (sugarcane drought-responsive 1). The aim of the research reported here was to characterize this gene. Scdr1 encodes a putative protein containing 248 amino acids with a large number of proline (19%) and cysteine (13%) residues. Phylogenetic analysis showed that ScDR1is in a clade with homologs from other monocotyledonous plants, separate from those of dicotyledonous plants. The expression of Scdr1 in different varieties of sugarcane plants has not shown a clear association with drought tolerance. Conclusions/Significance: The overexpression of Scdr1 in transgenic tobacco plants increased their tolerance to drought, salinity and oxidative stress, as demonstrated by increased photosynthesis, water content, biomass, germination rate, chlorophyll content and reduced accumulation of ROS. Physiological parameters, such as transpiration rate (E), net photosynthesis (A), stomatal conductance (gs) and internal leaf CO2 concentration, were less affected by abiotic stresses in transgenic Scdr1 plants compared with wild-type plants. Overall, our results indicated that Scdr1 conferred tolerance to multiple abiotic stresses, highlighting the potential of this gene for biotechnological applications.National Council for Scientific and Technological Development (CNPq)National Council for Scientific and Technological Development (CNPq)Fundacao de Amparo a Pesquisa de Sao Paulo (FAPESP)Fundacao de Amparo a Pesquisa de Sao Paulo (FAPESP) [2008/5798-6, 2008/57908-6]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) [574002/2008-1, 552802/2007-7]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Financiadora de Estudos e Projetos (FINEP) [815/07]Financiadora de Estudos e Projetos (FINEP

Analysis of gene expression profiles under water stress in tolerant and sensitive sugarcane plants

Water stress decreases plant productivity. To detect genes expressed under drought conditions, we performed a gene expression study using drought tolerant (SP83-5073) and sensitive (SP90-1638) sugarcane plants. Gene expression profiles were monitored by macroarray membranes containing 3575 cDNA clones from sugarcane leaf libraries, and the results were confirmed by real time PCR analysis. In the tolerant cultivar, we identified 165 genes that were expressed in response to water stress, in contrast with the sensitive cultivar, in which a higher number of genes (n = 432) were responsive to the stress treatment. The number of expressed genes in the sensitive cultivar increased with the severity of water deficit. In despite few genes had been differentially expressed in tolerant plants, 94% of them were up-regulated by stress, while 45% of the genes expressed in sensitive plants were down-regulated under water stress conditions. Comparing the gene expression profiles verified 91 common genes between both cultivars, the majority of which were up-regulated by water deficit. Genes were organized according to roles in cellular metabolism. Important stress-related pathways were repressed in sensitive plants. In both cultivars, we observed a great number of unknown genes, which will provide news insights in water deficit tolerance studies. (C) 2008 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Overexpression of an evolutionarily conserved drought-responsive sugarcane gene enhances salinity and drought resilience

Improving drought adaptation is more pressing for crops such as sugarcane, rice, wheat and maize, given the high dependence of these crops on irrigation. One option for enhancing adaptation to water limitation in plants is by transgenic approaches. An increasing number of genes that are associated with mechanisms used by plants to cope with water scarcity have been discovered. Genes encoding proteins with unknown functions comprise a relevant fraction of the genes that are modulated by drought. We characterized a gene in response to environmental stresses to gain insight into the unknown fraction of the sugarcane genome. Scdr2 (Sugarcane drought-responsive 2) encodes a small protein and shares highly conserved sequences within monocots, dicots, algae and fungi. Methods Plants overexpressing the Scdr2 sugarcane gene were examined in response to salinity and drought. Measurements of the gas exchange parameters, germination rate, water content, dry mass and oxidative damage were performed. Seeds as well as juvenile plants were used to explore the resilience level of the transgenic plants when compared with wild-type plants. Key Results Overexpression of Scdr2 enhanced germination rates in tobacco seeds under drought and salinity conditions. Juvenile transgenic plants overexpressing Scdr2 and subjected to drought and salinity stresses showed higher photosynthesis levels, internal CO2 concentration and stomatal conductance, reduced accumulation of hydrogen peroxide in the leaves, no penalty for photosystem II and faster recovery after submission to both stress conditions. Respiration was not strongly affected by both stresses in the Scdr2 transgenic plants, whereas wild-type plants exhibited increased respiration rates. Conclusions Scdr2 is involved in the response mechanism to abiotic stresses. Higher levels of Scdr2 enhanced resilience to salinity and drought, and this protection correlated with reduced oxidative damage. Scdr2 confers, at the physiological level, advantages to climate limitations. Therefore, Scdr2 is a potential target for improving sugarcane resilience to abiotic stress1244691700CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informação2008/57908-6K.B. was the recipient of a CNPq (National Council for Scientific and Technological Development) fellowship. This work was developed as part of the research network from the National Institute of Science and Technology of Bioethanol (Ministry of Science and Technology and grant 2008/57908-6 from FAPESP), and it was also partially funded by grant 815/07 from FINEP (Research and Projects Financing

Seed quality, chlorophyll content index and leaf nitrogen levels in maize inoculated with Azospirillum brasilense

The aim of this study was to evaluate differences between maize genotypes in relation to the germination response of the seeds and the growth of seedlings inoculated with Azospirillum brasilense, as well as the effect of inoculation on nitrogen levels and the chlorophyll content index of the leaves. The physiological seeds quality from the single-cross hybrids AG7098 and 2B707, and from the experimental synthetic varieties V2 and V4, inoculated with A. brasilense, was tested for germination, percentage and rate of emergence, and dry matter weight of the shoots and roots. Nitrogen levels and chlorophyll content index were evaluated in leaves of the same four genotypes grown in a greenhouse under different nitrogen supply systems and methods of inoculation with A. brasilense. The genotypes differ with regard to inoculation with A. brasilense. The hybrids were responsive to inoculation with A. brasilense for root dry matter weight. The V2 variety had a lower performance as regards root dry matter weight, with the opposite being seen for the dry matter weight of the shoots. V4 displayed no significant differences when inoculated. The results of the chlorophyll content index were not significant. Each genotype under evaluation displayed a different response for leaf nitrogen levels. It is possible to infer that the hybrids responded better to inoculation with the bacteria, with the greater root development leading to a better utilisation of water and nutrients.O objetivo deste estudo foi avaliar diferenças entre genótipos de milho quanto à resposta germinativa das sementes e crescimento de plântulas inoculadas com Azospirillum brasilense, assim como o efeito da inoculação no teor de nitrogênio e índice de conteúdo de clorofila foliar. A qualidade fisiológica de sementes dos híbridos simples, AG7098 e 2B707, e das variedades sintéticas experimentais, V2 e V4, inoculados com A. brasilense foi avaliada por meio de testes de germinação, porcentagem e velocidade de emergência e, massa de matéria seca de parte aérea e raiz. O teor de nitrogênio e o índice de conteúdo de clorofila foram avaliados em folhas dos mesmos quatro genótipos cultivados em casa de vegetação sob diferentes sistemas de fornecimento de nitrogênio e formas de inoculação com A. brasilense. Os genótipos diferem em relação à inoculação com A. brasilense. Os híbridos foram responsivos à inoculação com A. brasilense para massa de matéria seca de raiz. A variedade V2 apresentou comportamento inferior quanto à massa de matéria seca de raiz, mas o contrário foi observado para massa de matéria seca de parte aérea, e V4 não apresentou diferenças significativas quando inoculada. Os resultados de índice de conteúdo de clorofila não foram significativos. Para teor de nitrogênio foliar, cada genótipo avaliado respondeu de maneira particular. É possível inferir que os híbridos avaliados responderam melhor à inoculação com a bactéria, sendo que o maior desenvolvimento de raízes leva ao maior aproveitamento de água e nutrientes.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Seed quality, chlorophyll content index and leaf nitrogen levels in maize inoculated with Azospirillum brasilense

ABSTRACTThe aim of this study was to evaluate differences between maize genotypes in relation to the germination response of the seeds and the growth of seedlings inoculated with Azospirillum brasilense, as well as the effect of inoculation on nitrogen levels and the chlorophyll content index of the leaves. The physiological seeds quality from the single-cross hybrids AG7098 and 2B707, and from the experimental synthetic varieties V2 and V4, inoculated with A. brasilense, was tested for germination, percentage and rate of emergence, and dry matter weight of the shoots and roots. Nitrogen levels and chlorophyll content index were evaluated in leaves of the same four genotypes grown in a greenhouse under different nitrogen supply systems and methods of inoculation with A. brasilense. The genotypes differ with regard to inoculation with A. brasilense. The hybrids were responsive to inoculation with A. brasilense for root dry matter weight. The V2 variety had a lower performance as regards root dry matter weight, with the opposite being seen for the dry matter weight of the shoots. V4 displayed no significant differences when inoculated. The results of the chlorophyll content index were not significant. Each genotype under evaluation displayed a different response for leaf nitrogen levels. It is possible to infer that the hybrids responded better to inoculation with the bacteria, with the greater root development leading to a better utilisation of water and nutrients

Microtranscriptome analysis of sugarcane cultivars in response to aluminum stress.

Although several metallic elements are required for plant growth, excessive amounts of aluminum ions (Al3+) can result in the inhibition of root growth, thus triggering water and nutrient deficiencies. Plants under stress undergo gene expression changes in specific genes or post-transcriptional gene regulators, such as miRNAs, that can lead to stress tolerance. In this study, we investigated the miRNAs involved in the response of sugarcane to aluminum stress. Four miRNA libraries were generated using sugarcane roots of one tolerant and one sensitive sugarcane cultivar grown under aluminum stress and used to identify the miRNAs involved in the sugarcane aluminum toxicity response. The contrast in field phenotypes of sugarcane cultivars in the field during aluminum stress was reflected in the micro-transcriptome expression profiles. We identified 394 differentially expressed miRNAs in both cultivars, 104 of which were tolerant cultivar-specific, 116 were sensitive cultivar-specific, and 87 of which were common among cultivars. In addition, 52% of differentially expressed miRNAs were upregulated in the tolerant cultivar while the majority of differentially expressed miRNAs in the sensitive cultivar were downregulated. Real-time quantitative polymerase chain reaction was used to validate the expression levels of differentially expressed miRNAs. We also attempted to identify target genes of miRNAs of interest. Our results show that selected differentially expressed miRNAs of aluminum-stressed sugarcane cultivars play roles in signaling, root development, and lateral root formation. These genes thus may be important for aluminum tolerance in sugarcane and could be used in breeding programs to develop tolerant cultivars