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Global interest in sugarcane has increased significantly in recent years due to its economic impact on sustainable energy production. Sugarcane breeding and better agronomic practices have contributed to a huge increase in sugarcane yield in the last 30 years. Additional increases in sugarcane yield are expected to result from the use of biotechnology tools in the near future. Genetically modified (GM) sugarcane that incorporates genes to increase resistance to biotic and abiotic stresses could play a major role in achieving this goal. However, to bring GM sugarcane to the market, it is necessary to follow a regulatory process that will evaluate the environmental and health impacts of this crop. The regulatory review process is usually accomplished through a comparison of the biology and composition of the GM cultivar and a non-GM counterpart. This review intends to provide information on non-GM sugarcane biology, genetics, breeding, agronomic management, processing, products and byproducts, as well as the current technologies used to develop GM sugarcane, with the aim of assisting regulators in the decision-making process regarding the commercial release of GM sugarcane cultivars.

A new viviparous mutant of maize (Zea mays L.), associated with genetic instability and designated viviparous-12 (vp12), was identified in a synthetic Tuxpeño adapted to tropical regions. In the present work, the linkage group of this new locus was determined. Progenies of inbred line L477 segregating for the vp12 mutant were crossed with waxy-marked reciprocal translocation stocks. The phenotypic frequencies of the wx and vp12 mutants were analyzed in F2 progenies. The results demonstrated that the Viviparous-12 locus of maize is located on the long arm of chromosome 6.

Photosynthetic efficiency is considered one of the traits potentially suitable to differentiate hybrids from their inbred lines. Previous evaluations concerning photosynthetic efficiencies of maize (Zea mays L.) plants in the field have shown inconsistent and contradictory data. In this work, we attempted to study photosynthetic O2 evolution through photoacoustic spectroscopy in intact undetached leaves of dark-adapted seedlings of inbreds and their hybrids. The results indicate that photosynthetic efficiencies of inbreds and hybrids can be differentiated by photoacoustic measurements of oxygen evolution, providing a parameter that might prove useful in evaluating plant genotypes.

A new and highly sensitive method, based on the photoacoustic effect, is described for in vivo and in situ studies of photosynthetic activity of undetached leaves. The general utility of this simple photothermal method is demonstrated by examining the spectroscopy and photosynthetic activity of green, striped, and albino plants of maize (Zea mays L.).

O efeito do fotoperíodo curto na morfologia e biologia reprodutiva dos teosintos, Zea mays ssp. mexicana (Schräder) Iltis (raças Central Plateau e Chalco Los Reyes), Z. mays ssp. parviglumis var. huehuetenanguensis (Iltis & Doebley), Z. luxuriam (Durieu & Ascherson) Bird e Z. diploperennis (Iltis, Doebley & Guzman) e do milho mazóide 1-8, Z. mays ssp. mays L., foi estudado na Área Experimental da UNICAMP (SP) 22º54' latitude sul, de fevereiro a julho de 1989. Os representantes da espécie Z. mays ssp. mexicana foram os mais precoces, seguidos do Z. mays ssp. mays, Z. diploperennis, Z. luxurians e Z. mays ssp. parviglumis var. huehuetenanguensis. Pela análise canónica, observou-se que esses acessos de germoplasma estão distribuídos em 4 diferentes grupos, onde as características: início e fim da antese na panícula terminal e início e fim da antese nas panículas dos ramos laterais foram as principais responsáveis pela discriminação das várias populações de teosinto e do milho. Z. mays ssp. parviglumis var. huehuetenanguensis foi colocada num grupo intermediário entre representantes da Seção Zea e da Seção Luxuriantes. Esses resultados corroboram dados recentes de outros pesquisadores baseados em análises isoenzimáticas, e discordam portanto da classificação de Doebley & Iltis (1980), baseada na morfologia das inflorescências masculinas e forma da cúpula que reveste o fruto.The effect of short daylength on the morphology and reproduction of teosinte, Zea mays ssp. mexicana (Schräder) Iltis (races Central Plateau and Chalco Los Reyes), Z. mays ssp. parviglumis var. huehuetenanguensis (Iltis & Doebley), Z. luxurians (Durieu & Ascherson) Bird and Z. diploperennis (litis, Doebley & Guzman) were studied in comparison with a maize population at the experimental area of UNICAMP (SP), 22º54' S, on February-July 1989. Daily phenological observations showed that Z. mays ssp. mexicana populations were the earliest to flower followed by Z. mays ssp. mays, Z. diploperennis, Z. luxurians and Z. mays ssp. parviglumis var. huehuetenanguensis. According to a canonical analysis it was found that these germplasm accessions were distributed in four different groups according to the traits begining and ending of flowering of terminal panicles, and begining and ending of flowering of panicles of lateral branches. The population of Z. mays ssp. parviglumis var. huehuetenanguensis was placed as a intermediary group between Section Zea and Section Luxuriantes. These findings agree with recent works based on isoenzymatic analysis and disagree with the classification by Doebley & litis (1980) based on morphology of male inflorescence and shape of the cupule.

In the past ten years considerable progress has been made on plant regeneration from tissues, cells, and protoplasts of various Gramineae species. In maize, plant regeneration was first described in 19751. After the initial reports on somatic embryogenesis in maize in 19822,3, plant regeneration from embryo-derived callus was extended to numerous other genotypes4,5,6. Genetic variability for plant regeneration has been reported within maize germplasms adapted to temperate7,8,9,10,11 and tropical6 regions. Further studies on the genetic control of somatic embryogenesis are still needed to better understand and manipulate this trait. Considerable attention has also been directed at studying the genetic variability observed among plants derived from maize callus for use in genetics and breeding12,13,14,15. The possibility of regenerating plants from maize cell suspension and protoplast cultures has opened new perspectives for direct gene transfer. Nevertheless, reports on the establishment of maize cell suspension and protoplast cultures capable of regenerating plants remain limited to a few genotypes16,17,18,19.

An open-cell photoacoustic (OCPA) spectroscopic technique is described which can assess genetically rooted differences in the response of live specimens of corn (Zea Mays L.) to the toxic action of aluminium. Specimens from a susceptible and a tolerant inbred line were examined. The differences in their OCPA in vivo leaf spectra were evident and an interpretation is given based on the genetically controlled response of the inbreds to aluminium toxicity. An earlier discrimination among specimens is obtained with this technique than has been possible so far with previous techniques.

Photoacoustic spectroscopy is an efficient tool for the non-destructive assessment of chlorophyll and carotenoid deficient mutants of Zea mays L. Intact leaf samples taken from the mutants Albina, Luteus I and Luteus II were compared with those from the corresponding isogenic normals. The results are compared with those obtained applying some commonly used destructive techniques.

Lysine-ketoglutarate reductase activity was detected and characterized in the developing endosperm of maize (Zea mays L.). The enzyme showed specificity for its substrates: lysine, alpha-ketoglutarate, and NADPH. Formation of the reaction product saccharopine was demonstrated. The pH optimum of the enzyme was close to 7, and the K(m) for lysine and alpha-ketoglutarate were 5.2 and 1.8 millimolar, respectively.

A cultura da cana-de-açúcar está exposta a diversos patógenos, entre eles, o fungo Sporisorium scitamineum, agente causal do carvão, que causa perdas significativas na produção e na qualidade do caldo. O uso de genótipos resistentes é o principal método de controle da doença, o que torna essencial o conhecimento das bases genéticas da resistência, favorecendo a seleção de genótipos superiores. Neste estudo, uma população F1 segregante, derivada do cruzamento entre \'IAC66-6\' e \'TUC71-7\', foi genotipada usando marcadores EST-SSR e TRAP, os quais foram alocados em um mapa prévio, visando identificar marcadores associados a locos quantitativos de resistência a esse patógeno. A incidência de carvão foi avaliada em dois ensaios realizados nos anos de 2009 e 2010, em delineamento experimental inteiramente casualizado. O principal sintoma do carvão (número de chicotes) foi tomado ao longo dos ensaios e os dados foram utilizados para o cálculo da área sob a curva de progresso da doença (AUDPC), sendo os valores de AUDPC normalizados e analisados por meio de modelos mistos. O mapeamento de locos quantitativos (QTL) seguiu a abordagem de mapeamento por intervalo composto (CIM). O mapa aqui construído contém 721 marcadores, compilando EST-SSRs, TRAPs, além de AFLPs e marcadores direcionados ao retrotransposon scIvana_1 já alocados no mapa prévio. Estes foram posicionados em 124 grupos de co-segregação, sendo 65 deles atribuídos em dez grupos de homo(eo)logia, com base em locos EST-SSR em comum. O mapa totaliza 6.223,0 cM e tem uma densidade média de um marcador a cada 8,6 cM. O uso da metodologia CIM permitiu detectar oito locos quantitativos associados à resistência de S. scitamineum, sendo quatro deles identificados na primeira avaliação, dois novos locos na segunda avaliação e dois considerando-se o comportamento médio dos genótipos nos dois anos de avaliação. Observou-se a predominância de alelos com efeitos aditivos de resistência, comparativamente aos efeitos de dominância, sendo seis deles relacionados à diminuição da suscetibilidade e quatro com o aumento. Dentre os QTL, cinco segregaram na proporção 1:1, dois 3:1 e um na proporção de 1:2:1. Os QTLs foram capazes de explicar individualmente de 3,4% a 5,7% da variação fenotípica. O QTL que explicou a maior porcentagem da variação, detectado na primeira avaliação (5,7%), foi posicionado a 5,0 cM de outro QTL considerando-se o comportamento médio dos genótipos, sugerindo que estes QTLs localizam-se na mesma região genômica. Interessantemente, um dos QTLs está posicionado em um intervalo que contém uma marca TRAP e outra ancorada no retrotransposon scIvana. Espera-se que esses resultados contribuam para estudos futuros sobre genes candidatos envolvidos na resistência, o papel dos retrotransposons na resposta da planta a patógenos, bem como possam dar subsídios a programas de seleção assistida por marcadores. The sugarcane is exposed to several pathogens, including the fungus Sporisorium scitamineum, the smut disease´s causal agent, which causes significant losses in yield and juice quality. The use of resistant genotypes is the main strategy to control the disease, therefore it is essential the knowledge on the genetic basis of resistance for selecting superior genotypes. In this study, a F1 segregating population derived from a cross between \'IAC66-6\' and \'TUC71-7\' were genotyped using EST-SSR and TRAP markers that were placed on a prior map aiming at to identify markers associated to the smut resistance genes. The incidence of smut was evaluated in two trials performed in 2009 and 2010 in a completely randomized design. The main smut symptom (number of whips) was recorded in both trials, and data were used to calculate the area under the disease-progression curve (AUDPC). The values were normalized and analyzed using mixed models. The mapping of quantitative loci (QTL) followed the composite interval mapping (CIM) method. The map here in constructed contains 721 single dose markers compiling EST-SSRs, TRAPs as well as AFLPs and markers anchored in the retrotransposon scIvana_1, both previously allocated. Markers were positioned on 124 co-segregation groups, and 65 of them were assigned to ten groups of homo(eo)logy, based on common EST-SSR loci. The map totalized 6223.0 cM with a marker density of one marker every 8.6 cM. The use of CIM methodology allowed the detection of eight loci associated with quantitative resistance to S. scitamineum, four being identified in the first trial, two new QTLs in the second trial, and two considering the average genotype behavior in both years of evaluation. There was predominance of additive effects in comparison to the dominance effects, six of them related to decreased susceptibility and four related to increased susceptibility. Out of the QTLs, five segregated in a 1:1 ratio, two in a 3:1 ratio, and two in a 1:2:1 ratio. QTLs were able to explain individually 3.4% to 5.7% of the phenotypic variation. The QTL that explained the largest percentage of the variation, detected in the first trial (5.7%) was located at a distance of 5.0 cM from other QTL detected when considering the genotype average behavior, suggesting that these QTLs are positioned in the same genomic region. Interestingly, one QTL was located in an interval that contains a TRAP marker and a scIvana_1-anchored marker. We expect that our results contribute to future studies on disease resistance candidate genes, the role of retrotransposon in plant responses to pathogens, as well as to add marker-assisted selection programs.

A cultura do milho (Zea mays L.) apresenta grande importância cultural, social e econômica, tanto no Brasil como no mundo. Entre os fatores que contribuem grandemente para a diminuição de sua produtividade estão as doenças. A mancha de cercospora ou cercosporiose, causada pelo fungo Cercospora zeae-maydis Tehon & Daniels, é uma das principais doenças da cultura em vários países. Uma vez que o uso de híbridos resistentes é a medida mais eficiente para o seu controle, a caracterização e a discriminação de genótipos de milho quanto ao nível de resistência e de isolados do patógeno quanto ao nível de agressividade é uma etapa fundamental de qualquer programa de melhoramento. Isolados de C. zeae-maydis podem ser classificados em dois grupos genéticos, denominados I e II, segundo análise por marcadores AFLP e por restrição da região intergênica espaçadora do rDNA 5.8S. No Brasil, há ocorrência dos dois grupos, mas nos Estados Unidos há uma prevalência do grupo I sobre o grupo II, ao passo que em países do sul da África verifica-se somente a presença de indivíduos do grupo II. Presentemente, não há nenhum relato sistemático sobre diferenças em agressividade entre indivíduos destes grupos. Assim, o objetivo deste trabalho foi avaliar a agressividade de 20 isolados de C. zeae-maydis dos grupos genéticos I e II quando inoculados em um híbrido de milho suscetível e também testar o comportamento de 10 linhagens de milho frente a oito isolados em dois ambientes para verificar a possível presença de interação diferencial entre isolado, linhagem e local. Para tanto, os isolados foram cultivados em sementes de sorgo para produção de inóculo. Sementes colonizadas foram depositadas no cartucho das plantas e as avaliações foram realizadas utilizando-se escalas diagramáticas. No experimento em casa de vegetação foi verificada uma variação em agressividade entre os isolados do grupo genético I, do grupo genético II e entre os grupos. Observou-se ainda que isolados pertencentes ao grupo genético II são, em média, mais agressivos que isolados do grupo genético I. Este é o primeiro relato de diferenças em agressividade entre os grupos genéticos. No experimento em campo não foram observadas diferenças significativas quanto à agressividade dos isolados avaliados em Jardinópolis (SP) e Indianópolis (MG). Entretanto, observou-se forte interação entre linhagens e locais, indicando que o ambiente exerce influência na doença. Dessa forma, recomendam-se avaliações em ambientes diferentes e a utilização de isolados mais agressivos e pertencentes aos dois grupos genéticos a fim de otimizar a discriminação de genótipos de milho com relação à resistência a C. zeae-maydis. Maize (Zea maydis L.) is of great social, cultural and economical importance in Brazil and in the world. Maize diseases are the main factors that reduce crop yield. Gray leaf spot, caused by the fungus Cercospora zeae-maydis Tehon & Daniels, is one of the most important diseases in many countries. Given that the disease can be controlled by the use of resistant maize hybrids, the characterization and discrimination of maize genotypes according to their level of resistance and of pathogen isolates according to their aggressiveness are fundamental steps in any breeding program. Isolates of C. zeae-maydis can be classified into two genetic groups, named I and II, by analysis with AFLP markers and restriction of the intergenic spacer region of the 5.8S rDNA. In Brazil, both groups occur whereas in the United States isolates from group I prevail and in some South African countries only isolates from group II can be found. Presently, there are no systematic reports on differences in aggressiveness between these groups. Therefore, the objective of this study was to evaluate the aggressiveness of 20 isolates of C. zeae-maydis from both genetic groups when inoculated in a susceptible maize hybrid and also to test the reaction of 10 maize inbreds to eight C. zeae-maydis isolates in two environments in order to assess the possible occurrence of differential interaction between isolates, inbreds, and locations. Isolates were cultivated in sorghum seeds for innoculum production. Colonized seeds were placed into the whorl of the plants and the disease reaction was evaluated using a diagrammatic scale. In the greenhouse experiment significant variation in aggressiveness was observed among isolates of group I, group II and between groups. Also, it was observed that isolates from group II were, on average, more aggressive than isolates from group I. This is the first report on differences in aggressiveness between the two genetic groups of C. zeae-maydis. In the field experiment no significant differences were observed in aggressiveness among isolates evaluated in Jardinópolis (SP) and Indianópolis (MG) for the inbreds tested. However, a strong interaction between reactions of maize inbreds and regions was observed indicating that the environment influences the disease. Thus, evalutions in several locations with aggressive isolates from both groups is recommended in order to optimize the discrimination of maize genotypes regarding their resistance to C. zeae-maydis.

As pesquisas com os peptídeos hormonais de plantas se iniciaram na década de noventa com a descoberta da sistemina. Hoje existem diversos peptídeos identificados, e alguns deles já em avançado estágio de caracterização. O envolvimento desta classe de moléculas em diversas funções básicas e específicas da biologia dos vegetais despertou o interesse da comunidade científica. Dentre os peptídeos em fase de caracterização, destacam-se os representantes da família RALF. Os peptídeos RALF estão presentes em basicamente todo o reino vegetal, desde o musgo Physcomitrela pattens até as plantas superiores mono e dicotiledôneas. A conservação destes peptídeos no reino vegetal sugere um importante papel na fisiologia vegetal, e evidências recentes indicam a participação de RALF em processos básicos do desenvolvimento das plantas. O mecanismo pelo qual o peptídeo RALF atua e é percebido pela célula constitui etapa fundamental para sua caracterização funcional. Para tanto, no presente trabalho foram empregadas técnicas para identificação de proteínas de interação com RALF. Os resultados indicam que este peptídeo possivelmente tem sua atividade regulada pelo íon cálcio, através da interação com uma proteína de ligação a cálcio que, assim como o RALF, é secretada para o apoplasto. Estes dados colocam RALF em um cenário até o momento inédito no mecanismo de ação hormonal em plantas. A exemplo de animais e leveduras, observou-se também que o processamento de RALF ocorre em um sítio dibásico. A mutação de um dos aminoácidos deste sítio foi suficiente para impedir processamento do peptídeo in vivo e in vitro. A utilização de extratos protéicos da fração microsomal de Arabidopsis no ensaio in vitro indica que esta atividade é desempenhada por uma protease presente no sistema de endomembranas celular, provavelmente da classe das convertases. Os resultados publicados marcam o início dos estudos de caracterização do processamento de prohormônios em plantas. The peptide hormone research has begun during the 90s decade with the systemin discovery. Nowadays several peptides have already been identified, and some of them are further characterized. The involvement of these molecules with a range of basic and specific biological functions has raised the scientific communitys interest. Among the peptides being studied, the RALF family is particularly intriguing. The RALF peptides can be found throughout the plant kingdom, from the moss Physcomitrella patens to the mono and dicot plant groups. The conserved occurrence of these peptides along the plant kingdom suggests an important role in the plant physiology field. Recent evidences indicate that RALF plays a role in basic mechanisms of plant development. The RALF mechanism of action and its perception by the cell are fundamental information in order to characterize this peptide function. In the present work experiments to identify RALF interacting proteins were employed. The results indicate that RALF peptides activity is possibly regulated by the calcium ion. This regulation is mediated by the interaction with a calcium binding protein. This calcium binding protein was found to be secreted to the apoplast. Presented data suggests that RALF is regulated by a mechanism never described before in the plant hormone research field. As previously described in animals and yeast the RALF propeptide processing takes place in a dibasic site. A single amino acid site specific mutation disrupted peptide processing in vivo and in vitro. The correct processing is mediated by proteases of the Arabidopsis microsomal fraction. This processing seems to occur at the endomembrane system, possibly catalized by a convertase class enzyme. The published results points the beginning of the peptide processing studies in plants.