Sel’skokhozyaistvennaya Biologiya [Agricultural Biology], 2011, № 5, p. 51-55 UDC 635.263:578.85/.86:578.2:577.217 THE DICER-LIKE PROTEINS CODING NUCLEOTIDE SEQUENCES IN SHALLOT Allium cepa L. var. aggregatum G. Don A.V. Arkhipov, V.K. Vishnichenko All-Russia Research and Development Institute of Agricultural Biotechnology, RAAS, Moscow 127550, Russia e-mail: vish@iab.ac.ru Received June 6, 2011 S u m m a r y For the first time in the world literature the authors presented the evidence of expression in shallot plants(Allium cepa L. var. aggregatum G. Don) of nucleotide sequences coding the polypeptides homologous to known plant Dicer-like protein (DCL), obtained by PCR, sequencing and computer analysis. <...> The investigated polypeptides contain specific for DCL-protein the dsRNA bind, PAZ and RIBOc domens. <...> The solution of assigned task is available only with use of diagnostic oligonucleotide primers, the design of which was accomplished on the basis of information on EST-sequences (expressed sequence tags) in Allium sativum (GarlicESTdb integrated database). <...> The results permit to draw a conclusion about high extent of divergence of DCL-proteins in Arabidopsis, poplar, rice, on the one hand, and the plants of Allium genus, on the other hand, that is revealed on level both nucleotide sequences of mRNA, and amino acid sequences of studied polypeptides. <...> Keywords: RNA-interference, Dicer&Dicer-like (DCL) proteins, shallot (Allium cepa L. var. aggregatum), Shallot virus X. In plants, the degree of expression of many genes can be modulated at epigenetic level trough RNA interference, which mechanisms involve the key elements – endoribonucleases (RNase III) Dicer or Dicer-like (DCL), endonucleases Argonautes (AGOs) and cellular RNA-dependent RNA polymerase ( RDR) (1). <...> The action of these enzymes results in a wide range of small RNAs (microRNAs and small interfering RNA - siRNA) participating different biological processes, particularly those involved in development of plants (2). <...> Phytoviruses are potent exogenous inducers of RNA interference in plants; viral infection leads to a socalled virus-induced gene silencing, VIGS (3), that develops as the result of specific cleavage of replication viral RNA (doublestranded) by plant DCL-proteins. <...> Degradation of viral RNA by these endoribonucleases is accompanied by formation <...>