RESUMO
Recent studies have identified microRNAs as post-transcriptional regulators involved in stress responses. miR1514a is a legume microRNA that is induced in response to drought stress in Phaseolus vulgaris (common bean) and shows differential accumulation levels in roots during water deficit in two cultivars with different drought tolerance phenotypes. A recent degradome analysis revealed that miR1514a targets the transcripts of two NAC transcription factors (TFs), Phvul.010g121000 and Phvul.010g120700. Furthermore, expression studies and small RNA-seq data indicate that only Phvul.010g120700 generates phasiRNAs, which also accumulate under water deficit conditions. To confirm these results, we over-expressed miR1514a in transgenic hairy roots, and observed a reduced accumulation of Phvul.010g120700 and an increase in NAC-derived phasiRNAs; inhibition of miR1514a activity resulted in the opposite effect. Moreover, we determined that a NAC-derived phasiRNA associates with ARGONAUTE 1 (AGO1), suggesting that it is functional. In addition, a transcriptome analysis of transgenic hairy roots with reduced miR1514a levels revealed several differentially expressed transcripts, mainly involved in metabolism and stress responses, suggesting they are regulated by the NAC TF and/or by phasiRNAs. This work therefore demonstrates the participation of miR1514 in the regulation of a NAC transcription factor transcript through phasiRNA production during the plant response to water deficit.
Assuntos
Secas , Regulação da Expressão Gênica de Plantas , MicroRNAs/genética , MicroRNAs/fisiologia , Phaseolus/genética , Phaseolus/fisiologia , Fatores de Transcrição/genética , Produtos Agrícolas/genética , Produtos Agrícolas/fisiologia , Estresse Fisiológico/genética , Estresse Fisiológico/fisiologiaRESUMO
As sessile organisms, plants have to cope with the ever-changing environment as well as with numerous forms of stress. To react to these external cues, plants have evolved a suite of response mechanisms operating at many different levels, ranging from physiological to molecular processes that provide the organism with a wide phenotypic plasticity, allowing for fine tuning of the reactions to these adverse circumstances. During the past decade, non-coding RNAs (ncRNAs) have emerged as key regulatory molecules, which contribute to a significant portion of the transcriptome in eukaryotes and are involved in the control of transcriptional and post-transcriptional gene regulatory pathways. Although accumulated evidence supports an important role for ncRNAs in plant response and adaptation to abiotic stress, their mechanism(s) of action still remains obscure and a functional characterization of the ncRNA repertoire in plants is still needed. Moreover, common features in the biogenesis of different small ncRNAs, and in some cases, cross talk between different gene regulatory pathways may add to the complexity of these pathways and could play important roles in modulating stress responses. Here we review the various ncRNAs that have been reported to participate in the response to abiotic stress in plants, focusing on their importance in plant adaptation and evolution. Understanding how ncRNAs work may reveal novel mechanisms involved in the plant responses to the environment.
Assuntos
Plantas/genética , Pequeno RNA não Traduzido/genética , Estresse Fisiológico/genética , Adaptação Fisiológica/genética , Evolução Biológica , Regulação da Expressão Gênica de Plantas/genética , RNA de Plantas/genética , RNA de Plantas/metabolismo , Pequeno RNA não Traduzido/fisiologiaRESUMO
This study is a retrospective review of 956 patients comparing cases first-assisted by physician assistants (PAs) to those first-assisted by surgeons, examining whether PAs can function safely and efficiently in the role of first assistant surgeon for cardiac surgery. No differences were found between the two cohorts.