A novel plant defensin-like gene of winter wheat is specifically induced during cold acclimation.
A novel cDNA clone, Tad1, was isolated from crown tissue of winter wheat after differential screening of cold acclimation-induced genes. The Tad1 cDNA encoded a 23kDa polypeptide with a potential N-terminal signal sequence. The putative mature sequence showed striking similarity to plant defensins or gamma-thionins, representing low molecular size antipathogenic polypeptides. High levels of Tad1 mRNA accumulation occurred within one day of cold acclimation in crown tissue and the level was maintained throughout 14 days of cold acclimation. Similar rapid induction was observed in young seedlings treated with low temperature but not with exogenous abscisic acid. In contrast to defensins from other plant species, neither salicylic acid nor methyl jasmonate induced expression of Tad1. The recombinant mature form of TAD1 polypeptide inhibited the growth of the phytopathogenic bacteria, Pseudomonas cichorii; however, no antifreeze activity was detected. Collectively, these data suggested that Tad1 is induced in cold-acclimated winter wheat independent of major defense signaling(s) and is involved in low temperature-induced resistance to pathogens during winter hardening.
Koike
Michiya
M
Winter Stress Laboratory, National Agricultural Research Center for Hokkaido Region, NARO, Hitsujigaoka, Toyohira-ku, Sapporo 062-8555, Japan.
Okamoto
Takashi
T
Tsuda
Sakae
S
Imai
Ryozo
R
D000064:Acclimatization; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D021301:Antifreeze Proteins / Q000494:pharmacology; D001483:Base Sequence; D003080:Cold Temperature; D018076:DNA, Complementary / Q000302:isolation & purification; D023082:Defensins; D017343:Genes, Plant; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000494:pharmacology; D018749:RNA, Plant / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015854:Up-Regulation
D000900:Anti-Bacterial Agents; D021301:Antifreeze Proteins; D018076:DNA, Complementary; D023082:Defensins; D010940:Plant Proteins; D018749:RNA, Plant