Moriyama H, Horiuchi H, Koga R, Fukuhara T
Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho, 3-5-8, Fuchu, Tokyo 183-8509, Japan.
J Biol Chem. 1999 Mar 12;274(11):6882-8. doi: 10.1074/jbc.274.11.6882.
We completely sequenced 13,936 nucleotides (nt) of a double-stranded RNA (dsRNA) of wild rice (W-dsRNA). A single long open reading frame (13,719 nt) containing the conserved motifs of RNA-dependent RNA polymerase and RNA helicase was located in the coding strand. The identity between entire nucleotide sequence of W-dsRNA and that of the dsRNA of temperate japonica rice (J-dsRNA, 13,952 nt) was 75.5%. A site-specific discontinuity (nick) was identified at nt 1,197 from the 5' end of the coding strand of W-dsRNA. This nick is also located at nt 1,211 from the 5' end in the coding strand of J-dsRNA. The dsRNA copy number was increased more than 10-fold in pollen grains of both rice plants. This remarkable increase may be responsible for the highly efficient transmission of J-dsRNA via pollen that we already reported. J-dsRNA and W-dsRNA were also efficiently transmitted to interspecific F1 hybrids. Seed-mediated dsRNA transmission to F2 plants was also highly efficient when the maternal parent was wild rice. The efficiency of dsRNA transmission to F2 plants was reduced when the maternal parent was temperate japonica rice; however, the reduced rates in F2 plants were returned to high levels in F3 plants.
我们对野生稻双链RNA（W-dsRNA）的13936个核苷酸（nt）进行了全序列测定。在编码链上发现了一个单一的长开放阅读框（13719 nt），其中包含依赖RNA的RNA聚合酶和RNA解旋酶的保守基序。W-dsRNA的整个核苷酸序列与温带粳稻双链RNA（J-dsRNA，13952 nt）的核苷酸序列同一性为75.5%。在W-dsRNA编码链5'端第1197 nt处鉴定出一个位点特异性间断（切口）。该切口在J-dsRNA编码链5'端第1211 nt处也有出现。两种水稻植株花粉粒中的双链RNA拷贝数增加了10倍以上。这种显著增加可能是我们之前报道的J-dsRNA通过花粉高效传播的原因。J-dsRNA和W-dsRNA也能有效地传递到种间F1杂种中。当母本为野生稻时，种子介导的双链RNA向F2植株的传递也非常高效。当母本为温带粳稻时，双链RNA向F2植株的传递效率降低；然而，F2植株中的降低率在F3植株中又恢复到高水平。
