Tobacco proteinase inhibitor I genes are locally, but not systemically induced by stress.
A cDNA library of tobacco mosaic virus (TMV)-infected tobacco was screened with polymerase chain reaction products obtained using a degenerate primer corresponding to proteinase inhibitor I (PI-I) of tomato and potato. The resulting clones encoded two highly similar, putative tobacco PI-I proteins, indicating that both genes identified in tobacco are probably expressed. The tobacco PI-I's were approximately 50% identical to wound-inducible potato and tomato PI-I and 80% identical to an ethylene-regulated tomato PI-I. Northern blot analyses indicated that healthy tobacco leaf contains only minor amounts of PI-I mRNA, and that the inhibitor genes are induced by TMV infection, salicylate treatment, ethephon spraying, UV light irradiation and wounding. The results indicate that the tobacco PI-I genes are coordinately expressed with the genes for the basic pathogenesis-related proteins. Contrary to PI-I genes of tomato and potato, wound induction of the tobacco genes occurs only locally; the upper, unwounded leaves do not show any wound-induced PI-I gene expression.
Linthorst
H J
HJ
Department of Biochemistry, Leiden University, Netherlands.
Brederode
F T
FT
van der Does
C
C
Bol
J F
JF
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA; D005786:Gene Expression Regulation; D007700:Kinetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D010947:Plants, Toxic; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015842:Serine Proteinase Inhibitors / Q000235:genetics* / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics*
C075489:PI-I protein, Nicotiana tabacum; D010940:Plant Proteins; D015842:Serine Proteinase Inhibitors; C053376:pathogenesis-related proteins, plant; D004247:DNA