Associação genômica ampla para mapeamento de QTLs ligados a conteúdos de proteína e óleo em soja

The objective of this work was to identify single-nucleotide polymorphism (SNP) markers linked with quantitative trait loci (QTLs) associated with increased contents of protein and oil in soybean. A total of 169 Brazilian soybean varieties, genotyped with 6,000 SNP markers, were evaluated. Protein and oil contents were obtained with the near-infrared reflectance method. Correlation and multiple linear regression analyses were used to identify linkage disequilibrium between SNP markers and the QTLs associated with the two characteristics. Seven QTLs were found to be associated with protein content, on six chromosomes (2, 6, 11, 12, 13, and 16), explaining 60.9% of the variation in this trait. For oil content, eight QTLs were identified on six chromosomes (1, 4, 5, 6, 17, and 19), explaining 78.3% of the variation in the trait. The correlation between the number of loci containing favorable alleles and the evaluated characteristics was 0.49 for protein content and 0.60 for oil content. The molecular markers identified are mapped in genomic regions containing QTLs previously mapped for both characteristics, which reinforces the association between these regions and the genetic control of oil and protein contents in soybean.O objetivo deste trabalho foi identificar marcadores de polimorfismos de nucleotídeo único (SNPs) ligados a locos controladores de características quantitativas (QTLs) associados a maiores conteúdos de proteína e óleo em soja. Foram avaliadas 169 cultivares brasileiras de soja, genotipadas com 6 mil marcadores SNPs. Os conteúdos de proteína e óleo foram obtidos pelo método de refletância no infravermelho próximo. As análises de correlação e regressão linear múltipla foram utilizadas para a identificação de desequilíbrio de ligação entre os marcadores SNPs e os QTLs associados às duas características. Foram identificados sete QTLs associados ao conteúdo de proteína, em seis cromossomos (2, 6, 11, 12, 13 e 16), o que explicou 60,9% da variação nesta característica. Para o conteúdo de óleo, foram identificados oito QTLs em seis cromossomos (1, 4, 5, 6, 17 e 19), o que explicou 78,3% da variação na característica. A correlação entre o número de locos com alelos favoráveis e as características avaliadas foi de 0,49 para o conteúdo de proteína e de 0,60 para o conteúdo de óleo. Os marcadores moleculares identificados estão mapeados em regiões genômicas que contêm QTLs previamente mapeados para as duas características, o que reforça a associação dessas regiões com o controle genético dos conteúdos de óleo e proteína em soj

Cross tolerance by heat and water stress at germination of common beans

Common beans are legumes of extreme importance for the food security of developing countries. Because it is widely cultivated in tropical and subtropical regions, it is subject to the stress effects caused by this type of climate, such as water stress and heat. Cross-tolerance allows plants to acclimate to a range of different stresses after exposure to a specific short-term stress. The present work had as objective to evaluate the induction of cross-tolerance by heat stress at 38ºC and water stress simulated by polyethylene glycol (PEG) in 3 different osmotic potentials in the germination of the brazilian cultivars IPR Uirapuru and IPR Campos Gerais in a randomized block design, setting up a 2 x 2 x 3 factorial scheme, with eight replicates of 25 seeds. The following variables were evaluated: percentage of germination, root and shoot length, and fresh root and shoot mass. The data were submitted to Tukey test with 5% significance. The results indicate a possible memory to the primary stress when the IPR UIRAPURU and IPR Campos Gerais varieties are subjected to an initial stress of 38°C, making them better adapt to an osmotic stress at the evaluated stages. The results indicated that there was a statistically significant difference of the treatments applied in relation to the germination of the cultivars where the cultivar IPR Uirapuru obtained higher germination indexes for all treatments evaluated when compared to the cultivar IPR Campos Gerais. The results indicate that in both cultivars there was induction of cross tolerance by heat followed by water stress

Salicylic acid at beans germination against salt stress

The common bean (Phaseolus vulgaris L.) is an important legume that is part of the daily food of the brazilians, being important for other countries. Because it is widely cultivated in almost all brasilian regions, is subject to environmental inclemencies, such as saline stress. Salicylic acid (S.A.) is an important plant hormone known to participate in pathways of systemic acquired resistance (SAR) against pathogens and also reported as a participant in the response to abiotic stresses. This study aimed to evaluate the action of salicylic acid prior to saline stress from three different concentrations of sodium chloride at the germination of a Brazilian common bean, cultivar Avaluna. The experiment was designed in randomized blocks, setting a 2x4 factorial scheme, with eight replicates of 25 seeds each. The following variables were evaluated: percentage of germination, root and shoot length, fresh root and shoot mass. The data were submitted to Tukey test with significance of 5%. The results indicated that there was statistically significant difference in the treatments in relation to the use of AS, that presented stable germination indexes for all evaluated treatments. This result was different from that observed in the treatments with water, where the increase of NaCl concentration resulted in a significant decrease in the percentage of germination. The results also indicated that, for the concentrations of NaCl and S.A. used in the cultivar Avaluna in this experiment, S.A. did not act as a protector against salt stress during the plant growth and development stage evaluated

Genes Acting on Transcriptional Control during Abiotic Stress Responses

Abiotic stresses are the major cause of yield loss in crops around the world. Greater genetic gains are possible by combining the classical genetic improvement with advanced molecular biology techniques. The understanding of mechanisms triggered by plants to meet conditions of stress is of fundamental importance for the elucidation of these processes. Current genetically modified crops help to mitigate the effects of these stresses, increasing genetic gains in order to supply the agricultural market and the demand for better quality food throughout the world. To obtain safe genetic modified organisms for planting and consumption, a thorough grasp of the routes and genes that act in response to these stresses is necessary. This work was developed in order to collect important information about essential TF gene families for transcriptional control under abiotic stress responses

Genetic variability in Brazilian wheat cultivars assessed by microsatellite markers

Wheat (Triticum aestivum) is one of the most important food staples in the south of Brazil. Understanding genetic variability among the assortment of Brazilian wheat is important for breeding. The aim of this work was to molecularly characterize the thirty-six wheat cultivars recommended for various regions of Brazil, and to assess mutual genetic distances, through the use of microsatellite markers. Twenty three polymorphic microsatellite markers (PMM) delineated all 36 of the samples, revealing a total of 74 simple sequence repeat (SSR) alleles, i.e. an average of 3.2 alleles per locus. Polymorphic information content (PIC value) calculated to assess the informativeness of each marker ranged from 0.20 to 0.79, with a mean of 0.49. Genetic distances among the 36 cultivars ranged from 0.10 (between cultivars Ocepar 18 and BRS 207) to 0.88 (between cultivars CD 101 and Fudancep 46), the mean distance being 0.48. Twelve groups were obtained by using the unweighted pair-group method with arithmetic means analysis (UPGMA), and thirteen through the Tocher method. Both methods produced similar clusters, with one to thirteen cultivars per group. The results indicate that these tools may be used to protect intellectual property and for breeding and selection programs

Genetic variability in Brazilian wheat cultivars assessed by microsatellite markers

Abstract Wheat (Triticum aestivum) is one of the most important food staples in the south of Brazil. Understanding genetic variability among the assortment of Brazilian wheat is important for breeding. The aim of this work was to molecularly characterize the thirty-six wheat cultivars recommended for various regions of Brazil, and to assess mutual genetic distances, through the use of microsatellite markers. Twenty three polymorphic microsatellite markers (PMM) delineated all 36 of the samples, revealing a total of 74 simple sequence repeat (SSR) alleles, i.e. an average of 3.2 alleles per locus. Polymorphic information content (PIC value) calculated to assess the informativeness of each marker ranged from 0.20 to 0.79, with a mean of 0.49. Genetic distances among the 36 cultivars ranged from 0.10 (between cultivars Ocepar 18 and BRS 207) to 0.88 (between cultivars CD 101 and Fudancep 46), the mean distance being 0.48. Twelve groups were obtained by using the unweighted pair-group method with arithmetic means analysis (UPGMA), and thirteen through the Tocher method. Both methods produced similar clusters, with one to thirteen cultivars per group. The results indicate that these tools may be used to protect intellectual property and for breeding and selection programs