Modification of lignin biosynthesis in transgenic Nicotiana through expression of an antisense O-methyltransferase gene from Populus.
An aspen lignin-specific O-methyltransferase (bi-OMT; S-adenosyl-L-methionine: caffeic acid/5-hydroxyferulic acid 3/5-O-methyltransferase, EC 2.1.1.68) antisense sequence in the form of a synthetic gene containing the cauliflower mosaic virus 35S gene sequences for enhancer elements, promoter and terminator was stably integrated into the tobacco genome and inherited in transgenic plants with a normal phenotype. Leaves and stems of the transgenes expressed the antisense RNA and the endogenous tobacco bi-OMT mRNA was suppressed in the stems. Bi-OMT activity of stems was decreased by an average of 29% in the four transgenic plants analyzed. Chemical analysis of woody tissue of stems for lignin building units indicated a reduced content of syringyl units in most of the transgenic plants, which corresponds well with the reduced activity of bi-OMT. Transgenic plants with a suppressed level of syringyl units and a level of guaiacyl units similar to control plants were presumed to have lignins of distinctly different structure than control plants. We concluded that regulation of the level of bi-OMT expression by an antisense mechanism could be a useful tool for genetically engineering plants with modified lignin without altering normal growth and development.
Dwivedi
U N
UN
Phytotechnology Research Center, Michigan Technological University, Houghton 49931-1295.
Campbell
W H
WH
Yu
J
J
Datla
R S
RS
Bugos
R C
RC
Chiang
V L
VL
Podila
G K
GK
D001483:Base Sequence; D018506:Gene Expression Regulation, Plant; D008031:Lignin / Q000032:analysis / Q000096:biosynthesis*; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D016372:RNA, Antisense / Q000235:genetics*; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism; D014197:Trees / Q000201:enzymology
D016372:RNA, Antisense; D008031:Lignin; D008780:Methyltransferases; C019608:caffeate O-methyltransferase