Characterization of autonomous Dart1 transposons belonging to the hAT superfamily in rice.
An endogenous 0.6-kb rice DNA transposon, nDart1-0, was found as an active nonautonomous element in a mutable virescent line, pyl-v, displaying leaf variegations. Here, we demonstrated that the active autonomous element aDart in pyl-v corresponds to Dart1-27 on chromosome 6 in Nipponbare, which carries no active aDart elements, and that aDart and Dart1-27 are identical in their sequences and chromosomal locations, indicating that Dart1-27 is epigenetically silenced in Nipponbare. The identification of aDart in pyl-v was first performed by map-based cloning and by detection of the accumulated transposase transcripts. Subsequently, various transposition activities of the cloned Dart1-27 element from Nipponbare were demonstrated in Arabidopsis. Dart1-27 in Arabidopsis was able to excise nDart1-0 and Dart1-27 from cloned sites, generating footprints, and to integrate into new sites, generating 8-bp target site duplications. In addition to Dart1-27, Nipponbare contains 37 putative autonomous Dart1 elements because their putative transposase genes carry no apparent nonsense or frameshift mutations. Of these, at least four elements were shown to become active aDart elements in transgenic Arabidopsis plants, even though considerable sequence divergence arose among their transposases. Thus, these four Dart1 elements and Dart1-27 in Nipponbare must be potential autonomous elements silenced epigenetically. The regulatory and evolutionary implications of the autonomous Dart1 elements and the development of an efficient transposon-tagging system in rice are discussed.
Shimatani
Zenpei
Z
National Institute for Basic Biology, Okazaki, 444-8585, Japan.
Takagi
Kyoko
K
Eun
Chang-Ho
CH
Maekawa
Masahiko
M
Takahara
Hiroyuki
H
Hoshino
Atsushi
A
Qian
Qian
Q
Terada
Rie
R
Johzuka-Hisatomi
Yasuyo
Y
Iida
Shigeru
S
Tsugane
Kazuo
K
D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics*; D020868:Gene Silencing; D005822:Genetic Vectors; D012275:Oryza / Q000235:genetics*; D030821:Plants, Genetically Modified; D014170:Transformation, Genetic
D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D018744:DNA, Plant; C036483:T-DNA