Molecular cloning and induction of β-1,3-glucanase gene from Nicotiana glutinosa L.

Abstract

Cloning and characterization of disease-response genes in plants could be an initial step toward understanding the complex disease resistance mechanism. To better understand the complex step, we isolated one of the pathogenesis-related proteins, β-1,3-glucanase, cDNA from a cDNA library of Nicotiana glutinosa showing systemic resistance. One clone (GN-3) was a partial cDNA of β-1,3-glucanase 800 bp in size with a 171 amino acid coding region. This clone had a 90% nucleotide homology with the β-1,3-glucanase gene of N. tabacum cv. BY4. A deduced amino acid sequence of GN-3 clones indicated a 91% identity with the β-1,3-glucanase of tobacco, 58% with that of Lycopersicon esculentum, and 51% with that of Glycine max. Northern blot analysis showed that expression of β-1,3-glucanase mRNAs was induced by TMV infection and salicylic acid treatment. In addition to that this gene was highly induced by CuSO4 and β-aminobutyric acid which are known as inducers of plant disease resistance. The possible role of this gene expression in relation to chemical-induced plant defense responses is discussed.