Validation of Novel Reference Genes for Reverse Transcription Quantitative Real-Time PCR in Drought-Stressed Sugarcane

One of the most challenging aspects of RT-qPCR data analysis is the identification of reliable reference genes. Ideally, they should be neither induced nor repressed under different experimental conditions. To date, few reference genes have been adequately studied for sugarcane (Saccharum spp.) using statistical approaches. In this work, six candidate genes (αTUB, GAPDH, H1, SAMDC, UBQ, and 25S rRNA) were tested for gene expression normalization of sugarcane root tissues from drought-tolerant and -sensitive accessions after continuous dehydration (24 h). By undergoing different approaches (GeNorm, NormFinder, and BestKeeper), it was shown that most of them could be used in combinations for normalization purposes, with the exception of SAMDC. Nevertheless three of them (H1, αTUB, and GAPDH) were considered the most reliable reference genes. Their suitability as reference genes validated the expression profiles of two targets (AS and PFPα1), related to SuperSAGE unitags, in agreement with results revealed by previous in silico analysis. The other two sugarcane unitags (ACC oxidase and PIP1-1), after salt stress (100 mM NaCl), presented their expressions validated in the same way. In conclusion, these reference genes will be useful for dissecting gene expression in sugarcane roots under abiotic stress, especially in transcriptomic studies using SuperSAGE or RNAseq approaches

Sugarcane (Saccharum X officinarum): A Reference Study for the Regulation of Genetically Modified Cultivars in Brazil

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

Differential response to aluminum in populations of Stylosanthus guianensis (Aubl.) Sw

O trabalho desenvolvido avaliou a resposta diferencial ao alumínio em 25 populações do Stylosanthus guianensis, urna leguminosa forrageira de origem americana e de ampla distribuição geográfica. Para tanto, as 25 populações foram submetidas a 4 diferentes concentrações de alumínio (0, 4, 8 e 12 ppm) em solução nutritiva. Foram utilizados corno parâmetros avaliativos o comprimento da raiz, comprimento da parte aérea, peso seco da raiz e peso seco da parte aérea. As análises dos diferentes ·caracteres estudados indicaram que haviam diferenças quanto a resposta das populações ao alumínio. O comprimento da raiz é o parâmetro mais indicado para determinar o efeito do alumínio, enquanto o comprimento da parte aérea foi o parâmetro que menor influência sofreu. Os outros caracteres situaram-se numa faixa de sensibilidade intermediária. A análise da regressão dos diferentes parâmetros em função dos níveis de alumínio, foi utilizada para discriminar as populações mais tolerantes das mais sensíveis. Os coeficientes angulares das regressões permitiram identificar as populações EMGOPA 136/75, EPAMIG 66 9/70, EPAMIG 366/76 e SEA 75013, como sensíveis ao alumínio e as populações EPAMIG 664/76, EPAMIG 682/76, EPAMIG 379/76 e SEA 68004 como as mais tolerantes entre as populações estudadas.The differential response to aluminum was evaluated in 25 populations of Stylosanthus guianensis a tropical leguminous forage species of American origin and wide geographical distribution. For such, the 25 populations were submited to 4 different aluminurn concentrations (0, 4, 8 and 12 ppm) in nutrient solution. The parameters used to evaluate the behavior of the different populations were the length of root, length of aerial portion, dry weigth of roots and the dry weight of the aerial portion. The variances of the different characters were analysed and indicated the existence of differences in response of the populations to aluminurn in nutrient solution. The length of root is the best pararneter to measure the sensibility or tolerance to aluminurn. The least influenced character was the aerial portion while the weight of roots and the weight of the aerial portion were considered of medium sensibility to aluminum toxity. The regression analysis of the different parameters as functions of the alurninum concentration was used to distinguish the more tolerant populations from the more sensible. The regressions angular coefficients (slope) permitted the identification of populations EMGOPA 136/75, EPAMIG 669/76, EPAMIG 336/76 and SEA 75013 as sensitive to aluminum and the populations EPAMIG 664/76, EPAMIG 682/76, EPAMIG 379/76 and SEA 68004 as being the most tolerant anongst the populations studied

Análise dialélica em clones de cana-de-açúcar

Visando avaliar a ação gênica predominante em caracteres de importância econômica da cana-de-açúcar e identificar cruzamentos com potencial genético favorável para o desenvolvimento de novos cultivares, avaliaram-se oito genótipos segundo um esquema em dialelo desbalanceado, e também, progênies de 44 cruzamentos no delineamento látice 7 x 7, com três repetições, no Centro de Pesquisa e Melhoramento da Cana-de-Açúcar (CECA), da Universidade Federal de Viçosa. Os caracteres estudados foram: Brix % caldo da cana, número de colmos, massa média de colmo, toneladas de colmos por hectare, toneladas de Brix por hectare e porcentagem de florescimento. Os resultados evidenciaram a importância tanto dos efeitos gênicos aditivos como dos não-aditivos na expressão das características avaliadas. Os genótipos SP82-6108 e IAC86-2210 e as combinações híbridas SP82-6108 x SP88-754, SP82-6108 x SP87-365, SP81-1763 x SP82-6108, IAC86-2210 x SP88-754, IAC86-2210 x SP86-96, IAC86-2210 x SP81-1763, SP88-819 x SP87-365, SP84-2029 x SP87-365 e SP88-754 x SP87-365, mostraram maior potencial para elevar a produtividade de cana-de-açúcar

Influência da profundidade de semeadura na germinação de gramíneas e leguminosas forrageiras

Na Estação Experimental Central do Instituto de Zootecnia em Nova Odessa (SP), foram testadas três espécies de leguminosas — labelabe (Macrotyloma lablab), soja-perene (Glicyne wighii) e galáxia (Galactia striala) — e duas espécies de gramíneas — braquiária (Brachiaria decumbens) e colonião (Panicum maximum) às profundidades de: 0,0, 2,5 e 5,0cm, com a finalidade de verificar o efeito do enterrio na germinação de sementes de diferentes tamanhos. Constatou-se que a profundidade de 2,5cm foi significativamente mais favorável às leguminosas e que a semeadura superficial propiciou melhor germinação às gramíneas, em casa de vegetação, sem limitação de água

Influência da profundidade de semeadura na germinação de gramíneas e leguminosas forrageiras

Na Estação Experimental Central do Instituto de Zootecnia em Nova Odessa (SP), foram testadas três espécies de leguminosas €” labelabe (Macrotyloma lablab), soja-perene (Glicyne wighii) e galáxia (Galactia striala) €” e duas espécies de gramíneas €” braquiária (Brachiaria decumbens) e colonião (Panicum maximum) às profundidades de: 0,0, 2,5 e 5,0cm, com a finalidade de verificar o efeito do enterrio na germinação de sementes de diferentes tamanhos. Constatou-se que a profundidade de 2,5cm foi significativamente mais favorável às leguminosas e que a semeadura superficial propiciou melhor germinação às gramíneas, em casa de vegetação, sem limitação de água

Validation of novel reference genes for reverse transcription quantitative real-time PCR in drought-stressed sugarcane

One of the most challenging aspects of RT-qPCR data analysis is the identification of reliable reference genes. Ideally, they should be neither induced nor repressed under different experimental conditions. To date, few reference genes have been adequately studied for sugarcane (Saccharum spp.) using statistical approaches. In this work, six candidate genes (αTUB, GAPDH, H1, SAMDC, UBQ, and 25S rRNA) were tested for gene expression normalization of sugarcane root tissues from drought-tolerant and -sensitive accessions after continuous dehydration (24 h). By undergoing different approaches (GeNorm, NormFinder, and BestKeeper), it was shown that most of them could be used in combinations for normalization purposes, with the exception of SAMDC. Nevertheless three of them (H1, αTUB, and GAPDH) were considered the most reliable reference genes. Their suitability as reference genes validated the expression profiles of two targets (AS and PFPα1), related to SuperSAGE unitags, in agreement with results revealed by previous in silico analysis. The other two sugarcane unitags (ACC oxidase and PIP1-1), after salt stress (100 mM NaCl), presented their expressions validated in the same way. In conclusion, these reference genes will be useful for dissecting gene expression in sugarcane roots under abiotic stress, especially in transcriptomic studies using SuperSAGE or RNAseq approaches

Expression analysis of sugarcane aquaporin genes under water deficit

The present work is a pioneer study specifically addressing the aquaporin transcripts in sugarcane transcriptomes. Representatives of the four aquaporin subfamilies (PIP, TIP, SIP, and NIP), already described for higher plants, were identified. Forty-two distinct aquaporin isoforms were expressed in four HT-SuperSAGE libraries from sugarcane roots of drought-tolerant and -sensitive genotypes, respectively. At least 10 different potential aquaporin isoform targets and their respective unitags were considered to be promising for future studies and especially for the development of molecular markers for plant breeding. From those 10 isoforms, four (SoPIP2-4, SoPIP2-6, OsPIP2-4, and SsPIP1-1) showed distinct responses towards drought, with divergent expressions between the bulks from tolerant and sensitive genotypes, when they were compared under normal and stress conditions. Two targets (SsPIP1-1 and SoPIP1-3/PIP1-4) were selected for validation via RT-qPCR and their expression patterns as detected by HT-SuperSAGE were confirmed. The employed validation strategy revealed that different genotypes share the same tolerant or sensitive phenotype, respectively, but may use different routes for stress acclimation, indicating the aquaporin transcription in sugarcane to be potentially genotype-specific

Agricultural Trade Liberalization: Policies and Implications for Latin America

This book investigates key issues in regard to liberalization of agricultural trade in the Western Hemisphere, including potential scenarios for liberalization at the regional and multilateral levels, the effects of U.S. and European Union agricultural policies on trade, and how a Free Trade Area of the Americas and a European Union-MERCOSUR trade agreement might affect agricultural trade flows. It also examines agricultural liberalization in the U.S.-Central America Free Trade Agreement and suggests a food security typology for use by the World Trade Organization.