Soybean has a wide range of applications in the industry and, due to its crop potential, its improvement is widely desirable. During drought conditions, soybean crops suffer significant losses in productivity. Therefore, understanding the responses of the soybean under this stress is an effective way of targeting crop improvement techniques. In this study, we employed the Suppressive Subtractive Hybridization (SSH) technique to investigate differentially expressed genes under water deficit conditions. Embrapa 48 and BR 16 soybean lines, known as drought-tolerant and -sensitive, respectively, were grown hydroponically and subjected to different short-term periods of stress by withholding the nutrient solution. Using this approach, we have identified genes expressed during the early response to water deficit in roots and leaves. These genes were compared among the lines to assess probable differences in the plant transcriptomes. In general, similar biochemical processes were predominant in both cultivars; however, there were more considerable differences between roots and leaves of Embrapa 48. Moreover, we present here a fast, clean and straightforward method to obtain drought-stressed root tissues and a large enriched collection of transcripts expressed by soybean plants under water deficit that can be useful for further studies towards the understanding of plant responses to stress.

O objetivo deste trabalho foi avaliar a expressão, por RT-qPCR, dos genes de nodulação nodC e nodW e do gene nopP da estirpe CPAC 15, que provavelmente atuam na infecção das raízes da soja. Foram realizados dois experimentos. No primeiro, a expressão dos genes foi avaliada nas células após a incubação com genisteína por 15 min, 1, 4 e 8 horas. Os resultados revelaram que os três genes apresentaram maior expressão imediatamente após o contato com o indutor (15 min). No segundo experimento, a bactéria foi cultivada na presença de indutores (genisteína ou exsudatos de sementes de soja) por 48 horas. A expressão dos três genes foi maior na presença de genisteína, com valores de expressão para nodC, nodW e nopP superiores ao controle. Os resultados obtidos confirmam a funcionalidade dos três genes na estirpe CPAC 15, com ênfase para o nopP, cuja funcionalidade em Bradyrhizobium japonicum foi descrita pela primeira vez.

The objective of this work was to evaluate, by RT-qPCR, the expression of the nodC and nodW nodulation genes and of the nopP gene of the CPAC 15 strain, which probably play a role in the infection of soybean roots. Two experiments were done. In the first, the gene expression was evaluated in cells after incubation with genistein for 15 min, 1, 4 and 8 hours. Results showed that the three genes showed higher expression immediately after contact with the inducer (15 min). In the second experiment, the bacterium was grown in the presence of inducers (genistein or soybean seed exudates) for 48 hours. The expression of the three genes was greater when induced by genistein, and the expression of nodC, nodW and nopP had higher values than the control. The results confirm the functionality of the three genes in the CPAC 15 strain, with an emphasis on the nopP, whose functionality in Bradyrhizobium japonicum was described for the first time.

A presença crescente de produtos derivados de plantas geneticamente modificadas (GM) na dieta humana e de animais tem levado ao desenvolvimento de métodos de detecção capazes de distinguir entre alimentos derivados da biotecnologia e alimentos convencionais. As técnicas de PCR convencional e em tempo real têm sido as mais utilizadas para detectar e quantificar resíduos GM em alimentos altamente processados, respectivamente. A extração de DNA é um passo crítico durante o processo de análise. Alguns fatores, tais como, degradação de DNA, efeito de matriz e a presença de inibidores da PCR, implicam que um limite de detecção ou quantificação estabelecido para um determinado método é restrito à matriz usada durante validação e não pode ser estendido a qualquer outra matriz fora do escopo do método. No Brasil, amostras de salsicha constituíram a principal classe de produtos, nas quais resíduos de soja Roundup Ready® (RR) foram detectados. Então a validação de metodologias para detecção e quantificação destes resíduos é urgente. Amostras de salsicha foram submetidas a dois diferentes métodos de extração de DNA: Wizard modificado e CTAB. O rendimento e a qualidade foram comparados em ambos os métodos. As amostras foram analisadas por PCR convencional e em tempo real para detecção e quantificação de resíduos de soja RR. Pelo menos 200 ng de DNA total da amostra de salsicha foram necessários para garantir uma quantificação confiável. Reações contendo concentrações de DNA abaixo deste limite apresentaram grande variação nos valores de porcentagem de GM esperados. Na PCR convencional, o limite de detecção variou de 1,0 a 500 ng, dependendo do conteúdo de soja GM na amostra. A precisão, performance e linearidade foram relativamente altas, indicando que o método de análise foi satisfatório.

The increasing presence of products derived from genetically modified (GM) plants in human and animal diets has led to the development of detection methods to distinguish biotechnology-derived foods from conventional ones. The conventional and real-time PCR have been used, respectively, to detect and quantify GM residues in highly processed foods. DNA extraction is a critical step during the analysis process. Some factors such as DNA degradation, matrix effects, and the presence of PCR inhibitors imply that a detection or quantification limit, established for a given method, is restricted to a matrix used during validation and cannot be projected to any other matrix outside the scope of the method. In Brazil, sausage samples were the main class of processed products in which Roundup Ready® (RR) soybean residues were detected. Thus, the validation of methodologies for the detection and quantification of those residues is absolutely necessary. Sausage samples were submitted to two different methods of DNA extraction: modified Wizard and the CTAB method. The yield and quality were compared for both methods. DNA samples were analyzed by conventional and real-time PCR for the detection and quantification of Roundup Ready® soybean in the samples. At least 200 ng of total sausage DNA was necessary for a reliable quantification. Reactions containing DNA amounts below this value led to large variations on the expected GM percentage value. In conventional PCR, the detection limit varied from 1.0 to 500 ng, depending on the GM soybean content in the sample. The precision, performance, and linearity were relatively high indicating that the method used for analysis was satisfactory.