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Ethylene negatively regulates local expression of plant defense lectin genes
Author(s) -
ZhuSalzman Keyan,
Salzman Ron A.,
Koiwa Hisashi,
Murdock Larry L.,
Bressan Ray A.,
Hasegawa Paul M.
Publication year - 1998
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1998.1040311.x
Subject(s) - biology , methyl jasmonate , salicylic acid , gene expression , biochemistry , gene , complementary dna , microbiology and biotechnology
Griffonia simplicifolia leaf lectin II (GS‐II) is a N ‐acetylglucosamine (GlcNAc) binding protein, consisting of large (rGS‐II) and small (sGS‐II) subunits, that is presumed to function in plant defense because both the holoprotein and the rGS‐II inhibited insect growth and development in feeding bioassays. A cDNA encoding sGS‐II has been isolated and the deduced peptide has sequence similarity to class III chitinases. However, neither the GS‐II holoprotein nor bacterially expressed recombinant sGS‐II proteins had detectable chitinase or lysozyme activities. Both rGS‐II and sGS‐II mRNAs accumulated in response to methyl jasmonate (Me‐JA) treatment but not after wounding in local leaves unless injury was followed by treatment with the ethylene action inhibitor norbornadiene (NBD). Salicylic acid (SA) suppressed wounding/NBD induction of GS‐II transcript accumulation and ethylene inhibited Me‐JA‐induced expression. Apparently, defensive gene expression induced by signal transduction through the octadecanoid pathway in local leaves is suppressed by stress induced ethylene that is produced as a consequence of wounding. However, in leaves systemic to the wound site, rGS‐II mRNA levels increased substantially indicating that physiological levels of ethylene are insufficient to down regulate defensive gene expression away from the site of injury. It seems that G. simplicifolia has evolved a rather specialized response to herbivore attack whereby local activation of defensive gene expression is attenuated in order to mount a more substantial defense distal to the site of invasion.