cDNA clones encoding 1,3-beta-glucanase and a fimbrin-like cytoskeletal protein are induced by Al toxicity in wheat roots.
A cDNA library made from mRNA of Al-treated roots of an Al-sensitive wheat (Triticum aestivum cv Victory) cultivar was screened with a degenerate oligonucleotide probe derived from the partial amino acid sequence of the Al-induced protein TAI-18. Of seven clones that initially hybridized with the probe, one encoded a novel 1,3-beta-glucanase having a calculated molecular weight of 46.3 and an isoelectric point of 6.0. Like the A6 1,3-beta-glucanase gene products from Brassica napus and Arabidopsis thaliana, the predicted wheat protein had a C-terminal extension with three potential glycosylation sites. Northern analysis revealed that wheat 1,3-beta-glucanase mRNA was up-regulated in Al-intoxicated roots, with highest expression after 12 h. The antibody to A6 1,3-beta-glucanase from B. napus cross-reacted with a 56-kD protein that was induced after 24 h. A second partial cDNA clone showed similarity to genes encoding cytoskeletal fimbrin-like (actin-bundling) proteins. Although well studied in animals and fungi, fimbrins have not previously been described in plants. Fimbrin-like transcripts were up-regulated after 24 h of Al treatment in the Al-sensitive wheat cv Victory. In the Al-tolerant cv Atlas 66, fimbrin-like mRNA was up-regulated within 12 h by Al concentrations that did not inhibit root growth. Cellular stress associated with Al toxicity therefore causes up-regulation of a defense-related gene and a gene involved in the maintenance of cytoskeletal function.
Cruz-Ortega
R
R
Department of Botany, Oklahoma State University, Stillwater 74078, USA.
Cushman
J C
JC
Ownby
J D
JD
D000535:Aluminum / Q000633:toxicity*; D000595:Amino Acid Sequence; D001937:Brassica / Q000201:enzymology; D003001:Cloning, Molecular; D003429:Cross Reactions; D003598:Cytoskeletal Proteins / Q000235:genetics*; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D043326:Glucan 1,3-beta-Glucosidase; D008562:Membrane Glycoproteins / Q000235:genetics*; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000187:drug effects* / Q000235:genetics; D001617:beta-Glucosidase / Q000235:genetics*
D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D012333:RNA, Messenger; C026742:plastin; D000535:Aluminum; D001617:beta-Glucosidase; D043326:Glucan 1,3-beta-Glucosidase