Auxin-induced elongation growth and expressions of cell wall-bound exo- and endo-beta-glucanases in barley coleoptiles.
When auxin stimulates rapid cell elongation growth of cereal coleoptiles, it causes a degradation of 1,3:1,4-beta-glucan in hemicellulosic polysaccharides. We examined gene expressions of endo-1,3:1,4-beta-glucanase (EI) and exo-beta-glucanase (ExoII), of which optimum pH are about 5, and molecular distribution of hemicellulosic polysaccharides in barley (Hordeum vulgare L.) coleoptile segments treated with or without IAA. IAA (10(-5) M) stimulated the gene expression of EI, while it did not affect that of ExoII. IAA induced gene expression of EI after 4 h and increased wall-bound glucanase activity after 8 h. The molecular weight distribution of hemicellulosic polysaccharides from coleoptile cell walls was shifted to lower molecular weight region by 2 h of IAA treatment. Fusicoccin (10(-6) M) mimicked IAA-induced elongation growth and the decrease in molecular weight of hemicellulosic 1,3:1,4-beta-glucan of coleoptiles in the first 4 h, but it did not promote elongation growth thereafter. These facts suggest that acidification of barley cell walls by IAA action enhances pre-existing cell wall-bound glucanase activity in the early first phase of IAA-induced growth and the late second phase involves the gene expression of EI by IAA.
Kotake
T
T
Department of Environmental Studies, Faculty of Integrated Arts & Sciences, Hiroshima University, Higashi-Hiroshima, 739-8521 Japan.
Nakagawa
N
N
Takeda
K
K
Sakurai
N
N
D015152:Blotting, Northern; D002473:Cell Wall / Q000187:drug effects* / Q000201:enzymology; D002480:Cellulase / Q000235:genetics*; D018548:Cotyledon / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D043326:Glucan 1,3-beta-Glucosidase; D005947:Glucose / Q000378:metabolism; D006027:Glycosides / Q000494:pharmacology; D001467:Hordeum / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008970:Molecular Weight; D010937:Plant Growth Regulators / Q000494:pharmacology; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D018749:RNA, Plant / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D001617:beta-Glucosidase / Q000235:genetics*
D006027:Glycosides; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D011134:Polysaccharides; D018749:RNA, Plant; C007808:fusicoccin; C030737:indoleacetic acid; C007916:hemicellulose; D001617:beta-Glucosidase; D002480:Cellulase; D043326:Glucan 1,3-beta-Glucosidase; D005947:Glucose