Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: In Medicago truncatula, water deficit modulates the transcript accumulation of components of small RNA pathways | Capitão et al. BMC Plant Biology 2011 11 79 http 1471-2229 11 79 BMC Plant Biology RESEARCH ARTICLE Open Access In Medicago truncatula water deficit modulates the transcript accumulation of components of small RNA pathways Cláudio Capitão 1 Jorge AP Paiva2 Dulce M Santos3 and Pedro Fevereiro1 4 Abstract Background Small RNAs sRNAs are 20-24 nucleotide nt RNAs and are involved in plant development and response to abiotic stresses. Plants have several sRNA pathways implicated in the transcriptional and post-transcriptional silencing of gene expression. Two key enzyme families common to all pathways are the Dicer-like DCL proteins involved in sRNAs maturation and the Argonautes AGOs involved in the targeting and functional action of sRNAs. Post-transcriptional silencing mediated by AGOs may occur by cleavage or translational repression of target mRNA s while transcriptional silencing may be controlled by DNA methylation and chromatin remodeling. Thus far these gene families have not been characterized in legumes nor has their involvement in adaptation to water deficit been studied. Results A bioinformatic search in Medicago truncatula genome databases using Arabidopsis thaliana AGO and DCL cDNA and protein sequences identified three sequences encoding for putative Dicer-like genes and twelve sequences encoding for putative Argonaute genes. Under water deficit conditions and mainly in roots MtDCL1 and MtAGO1 two enzymes probably involved in the processing and activation of microRNAs miRNAs increased their transcript levels. mir162 which target DCL1 mRNA and mir168 which target AGO1 mRNA reduced their expression in the roots of plants subjected to water deficit. Three putative genes MtDCL3 MtAGO4b and MtAGO4c probably involved in DNA methylation mechanisms increased their mRNA levels. However the mRNA levels of MtAGO6 reduced which probably encodes a protein with functions similar to MtAGO4. MtAGO7 mRNA levels increased and possibly encodes a .
