Sugarcane genes associated with sucrose content

<p>Abstract</p> <p>Background -</p> <p>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.</p> <p>Results -</p> <p>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.</p> <p>Conclusion -</p> <p>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.</p

Influência da época de colheita e do armazenamento em atmosfera controlada na qualidade da maçã 'Braeburn' Influence of harvest maturity and controlled atmosphere conditions on the quality of 'Braeburn' apple

Foi avaliado o efeito da época de colheita e das condições de armazenamento em atmosfera controlada sobre a firmeza da polpa, acidez titulável, ºBrix e, principalmente, sobre a ocorrência de degenerescência da polpa em maçãs (Malus domestica cv. Braeburn). Os tratamentos consistiram na combinação da data de colheita (27/3/1997 e 9/4/1997) com condição de armazenamento (temperatura de 0,5°C com: 1 kPa de O2/4,0 kPa de CO2; 1 kPa de O2/3,0 kPa de CO2; 1 kPa de O2/2,0 kPa de CO2; 21 kPa de O2/0,0 kPa de CO2, e temperatura de -0,5°C com: 1kPa de O2/3,0 kPa de CO2; 1 kPa de O2/2,0 kPa de CO2). Após oito meses de armazenamento, não foi observada suscetibilidade da maçã cv. Braeburn à baixa temperatura de armazenamento (-0,5ºC) e os frutos armazenados em ambiente refrigerado apresentaram baixa qualidade para o consumo. As condições de atmosfera controlada de 1 kPa de O2 associadas com 2 e 3 kPa de CO2 e a -0,5ºC apresentaram menor incidência de podridões, rachaduras e degenerescência senescente. Os frutos colhidos tardiamente, em 9/4/1997, apresentaram maior incidência de podridões, polpa farinhenta, degenerescência com cortiça e rachaduras. Nos parâmetros firmeza da polpa, acidez titulável e teor de sólidos solúveis totais não se observaram diferenças entre as condições de atmosfera controlada, após sete dias de exposição à temperatura de 25ºC.<br>This work was carried out to evaluate the effect of harvest maturity and controlled atmosphere on the quality and internal breakdown incidence in apples (Malus domestica) cv. Braeburn. The treatments consisted in the combination of harvest maturity (March 27, 1997 and April 9, 1997) with storage conditions (0.5°C with: 1 kPa O2/4 kPa CO2; 1 kPa O2/3 kPa CO2; 1 kPa O2/2 kPa CO2; 21 kPa O2/0 kPa CO2-cold storage and; -0.5°C with: 1 kPa O2/3 kPa CO2; 1 kPa O2/2 kPa CO2). After eight months of storage, there was no low temperature injury on fruits stored at -0.5ºC, and the cold storage fruits presented low quality for consumption. Under controlled atmosphere conditions of 1 kPa O2 combined with 2 and 3 kPa CO2 in -0.5ºC, the fruits presented lower rot, fruit cracking and internal breakdown incidence. Late harvested fruits (April 9, 1997) presented higher rot, mealy pulps, cork breakdown and craked fruits incidence. For flesh firmness, titratable acidity and TSS there was no significant difference among controlled atmosphere conditions after seven days in shelf life

Conservação da maçã (Malus domestica Borkh.) cv. Braeburn Storage in controlled atmosphere of 'Braeburn' (Malus domestica, Borkh.) apples

O experimento foi desenvolvido com o objetivo de avaliar o efeito da temperatura e de diferentes regimes de armazenamento em atmosfera controlada (AC) sobre as qualidades físico-químicas e ocorrência de distúrbios fisiológicos da maçã cv. Braeburn. O delineamento experimental foi o inteiramente casualizado, com duas repetições e a unidade experimental composta por 40 frutos. Os frutos foram armazenados nas seguintes condições de AC: na temperatura de 1ºC com 1,5kPaO2/ 4,0kPaCO2, 1,5kPaO2/3,0kPaCO2, 1,0kPaO2/1,0kPaCO2, 1,0kPaO2/2,0kPaCO2, 1,0kPaO2/3,0kPaCO2 e em armazenamento refrigerado (AR) e na temperatura de 0ºC com 1,0kPaO2/3,0kPaCO2 e em AR. A umidade relativa foi mantida a 96%. As análises laboratoriais foram realizadas aos oito meses de armazenamento, na abertura das câmaras e após sete dias de exposição à temperatura ambiente (±31ºC). Logo após a retirada dos frutos da câmara, não se observaram diferenças significativas na firmeza de polpa, acidez titulável e teor de sólidos solúveis totais (SST) entre as condições de AC. Contudo, após sete dias de exposição à temperatura ambiente, o tratamento com 1,0kPaO2/3,0kPaCO2, na temperatura de 0ºC, manteve a firmeza de polpa, acidez titulável e o teor de SST mais elevados, além de não exibir degenerescência senescente. O armazenamento em AC com 4,0kPa de CO2 e o armazenamento refrigerado causaram degenerescência senescente. Já a degenerescência com cortiça foi induzida pelo uso de 3,0 e 4,0kPa de CO2, associado com 1,5kPa de O2. As podridões foram significativamente maiores em AR do que em AC, sendo mais freqüente em baixa concentração de CO2 (1kPa). A incidência de rachaduras e escaldadura foi insignificante e não foi associada a nenhuma condição de armazenamento. No armazenamento refrigerado, os frutos apresentaram qualidade insatisfatória para a comercialização e consumo após oito meses de armazenamento.<br>The experiment was carried out with the objective of evaluating the effect of the temperature and of different controlled atmosphere (CA) storage regimes on the fruit qualities, and occurrence of physiological disorders of 'Braeburn' apples. The experimental design was the completely randomized with two replication. Fruits were stored in cold storage at 0 and 1ºC and in the following CA conditions: at temperature of 1ºC with 1,5kPaO2/4,0KkPaCO2, 1,5kPaO2/3,0kPaCO2, 1,0kPaO2/ 1,0kPaCO2, 1,0kPaO2/2,0kPaCO2, 1,0kPaO2/3,0kPaCO2 and at temperature of 0ºC with 1,0kPaO2/3,0kPaCO2. The relative humidity was maintained around 96%. The evaluation was done after eight months of storage, at the opening of the chambers and after seven days shelf life (31ºC). At chambers openning, there was no significant difference in the flesh firmness, titratable acidity and total soluble solids (TSS) among the CA conditions. However, after seven days in shelf life, the treatment with 1,0kPaO2/3,0kPaCO2 in the temperature of 0ºC maintained higher flesh firmness, titratable acidity and TSS, and did not exhibiting flesh breakdown. The CA storage, with 4,0kPa CO2 and cold storage caused flesh breakdown. Already the cork breakdown, was induced by 3,0 and 4,0kPa of CO2 associated with 1,5kPa of O2. The occurrence of rot was significantly higher in cold storage than in CA and more frequent al low CO2 (1kPa). The incidence of mealiness and scald could not be associated with any storage condition. Cold storage fruits presented unsatisfactory quality for marketing and consumption after 8 months of storage