Identification of novel soybean microRNAs involved in abiotic and biotic stresses.

BACKGROUND: Small RNAs (19-24 nt) are key regulators of gene expression that guide both transcriptional and post-transcriptional silencing mechanisms in eukaryotes. Current studies have demonstrated that microRNAs (miRNAs) act in several plant pathways associated with tissue proliferation, differentiation, and development and in response to abiotic and biotic stresses. In order to identify new miRNAs in soybean and to verify those that are possibly water deficit and rust-stress regulated, eight libraries of small RNAs were constructed and submitted to Solexa sequencing. RESULTS: The libraries were developed from drought-sensitive and tolerant seedlings and rust-susceptible and resistant soybeans with or without stressors. Sequencing the library and subsequent analyses detected 256 miRNAs. From this total, we identified 24 families of novel miRNAs that had not been reported before, six families of conserved miRNAs that exist in other plants species, and 22 families previously reported in soybean. We also observed the presence of several isomiRNAs during our analyses. To validate novel miRNAs, we performed RT-qPCR across the eight different libraries. Among the 11 miRNAs analyzed, all showed different expression profiles during biotic and abiotic stresses to soybean. The majority of miRNAs were up-regulated during water deficit stress in the sensitive plants. However, for the tolerant genotype, most of the miRNAs were down regulated. The pattern of miRNAs expression was also different for the distinct genotypes submitted to the pathogen stress. Most miRNAs were down regulated during the fungus infection in the susceptible genotype; however, in the resistant genotype, most miRNAs did not vary during rust attack. A prediction of the putative targets was carried out for conserved and novel miRNAs families. CONCLUSIONS: Validation of our results with quantitative RT-qPCR revealed that Solexa sequencing is a powerful tool for miRNA discovery. The identification of differentially expressed plant miRNAs provides molecular evidence for the possible involvement of miRNAs in the process of water deficit- and rust-stress responses.

Evaluation of economically important traits from sixteen parental strains of the silkworm Bombyx mori L (Lepidoptera: Bombycidae).

The classification and characterization of silkworm strains are important for sericulture, which is supported by the constant development of new hybrids. In this study, 16 parental strains of Bombyx mori L from the germplasm banks of the Universidade Estadual de Maringá--UEM, and Associação dos Criadores de Bicho-da-Seda de Nova Esperança e Regiões Sericícolas do Paraná--ACESP, were evaluated regarding biological and productive traits economically important. The Chinese C122-B and C121-A, and the Japanese HA-A and HA-B strains yielded the highest cocoon weight, which is related to the raw silk percentage. Our data will be useful in breeding programs for the production of superior silkworm strains and hybrids.

Evaluation of economically important traits from sixteen parental strains of the silkworm Bombyx mori L (Lepidoptera: Bombycidae) / Avaliação de características economicamente importantes de dezesseis linhagens do bicho-da-seda Bombyx mori L (Lepidoptera: Bombycidae)

The classification and characterization of silkworm strains are important for sericulture, which is supported by the constant development of new hybrids. In this study, 16 parental strains of Bombyx mori L from the germplasm banks of the Universidade Estadual de Maringá - UEM, and Associação dos Criadores de Bicho-da-Seda de Nova Esperança e Regiões Sericícolas do Paraná - ACESP, were evaluated regarding biological and productive traits economically important. The Chinese C122-B and C121-A, and the Japanese HA-A and HA-B strains yielded the highest cocoon weight, which is related to the raw silk percentage. Our data will be useful in breeding programs for the production of superior silkworm strains and hybrids.

A classificação e caracterização de linhagens de Bombyx mori L é importante para a sericicultura, uma vez que essa atividade é sustentada pelo constante desenvolvimento de novos híbridos da espécie. Neste trabalho, 16 linhages parentais de B. mori do banco de germoplasma da Universidade Estadual de Maringá - UEM, e da Associação dos Criadores de Bicho-da-Seda de Nova Esperança e Regiões Sericícolas do Paraná - ACESP, foram avaliadas em relação às características biológicas e produtivas consideradas economicamente importantes. As linhagens C122-B e C121-A, de origem Chinesa, e as HA-A e HA-B, Japonesas, apresentaram o maior peso de casulo (CW), o qual é associado ao teor de seda (RSP). Os resultados apresentados neste trabalho podem ser utilizados em vários programas de melhoramento visando à produção de linhagens e híbridos geneticamente superiores.