A novel plant defensin-like gene of winter wheat is specifically induced during cold acclimation

• Published in: Biochemical and biophysical research communications Vol. 298; no. 1; pp. 46 - 53
• Main Authors: Koike, Michiya, Okamoto, Takashi, Tsuda, Sakae, Imai, Ryozo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18-10-2002
• Subjects: Acclimatization; Amino Acid Sequence; Anti-Bacterial Agents - pharmacology; Antifreeze protein; Antifreeze Proteins - pharmacology; Antimicrobial protein; Base Sequence; Cold acclimation; Cold Temperature; Defensins; DNA, Complementary - isolation & purification; Genes, Plant; Molecular Sequence Data; Phylogeny; Plant defensin; Plant Proteins - biosynthesis; Plant Proteins - genetics; Plant Proteins - pharmacology; RNA, Plant - biosynthesis; Sequence Homology, Amino Acid; Thionin; Triticum - genetics; Triticum - metabolism; Triticum - physiology; Up-Regulation; Plant defensin; Antimicrobial protein; Antifreeze protein; Thionin; Cold acclimation
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/S0006-291X(02)02391-4

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 23
kDa polypeptide with a potential N-terminal signal sequence. The putative mature sequence showed striking similarity to plant defensins or γ-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.