tailieunhanh - báo cáo khoa học: " Phloem small RNAs, nutrient stress responses, and systemic mobility"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Phloem small RNAs, nutrient stress responses, and systemic mobility | Buhtz et al. BMC Plant Biology 2010 10 64 http 1471-2229 10 64 BMC Plant Biology RESEARCH ARTICLE _ Open Access Phloem small RNAs nutrient stress responses and systemic mobility Anja Buhtz21 Janin Pieritzt2 Franziska Springer2 and Julia Kehr 1 Abstract Background Nutrient availabilities and needs have to be tightly coordinated between organs to ensure a balance between uptake and consumption for metabolism growth and defense reactions. Since plants often have to grow in environments with sub-optimal nutrient availability a fine tuning is vital. To achieve this information has to flow cell-to-cell and over long-distance via xylem and phloem. Recently specific miRNAs emerged as a new type of regulating molecules during stress and nutrient deficiency responses and miR399 was suggested to be a phloem-mobile longdistance signal involved in the phosphate starvation response. Results We used miRNA microarrays containing all known plant miRNAs and a set of unknown small s RNAs earlier cloned from Brassica phloem sap 1 to comprehensively analyze the phloem response to nutrient deficiency by removing sulfate copper or iron respectively from the growth medium. We show that phloem sap contains a specific set of sRNAs that is distinct from leaves and roots and that the phloem also responds specifically to stress. Upon S and Cu deficiencies phloem sap reacts with an increase of the same miRNAs that were earlier characterized in other tissues while no clear positive response to -Fe was observed. However -Fe led to a reduction of Cu- and P-responsive miRNAs. We further demonstrate that under nutrient starvation miR399 and miR395 can be translocated through graft unions from wild type scions to rootstocks of the miRNA processing hen1-1 mutant. In contrast miR171 was not transported. Translocation of miR395 led to a down-regulation of one of its targets in rootstocks suggesting that this transport is of functional relevance and that miR395 in addition to the .