Studies on the mechanism of auxin-induced elongation growth in Poaceae plants

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We purified and identified five glucanases bound to barley cell walls ; [1], endo-1,3 ; 1,4-glucanase (31KD) ; [2], endo-1,3-glucanase-1 (31kD) ; [3], endo-1,3-glucanase-2 (31kD) ; [4], exo-glucanase-1 (66kD) ; [5], exo-glucanase-2 (68kD). The enzymes involved in 1,3 ; 1,4-glucan degradation in cereal plants are likely glucanase [1] and [4]. The exo-glucanase-1 [4] has the highest activity toward 1,3 ; 1,4-beta-glucans, and accounts for the 60% of total glucanase activity bound to the cell walls. The endo-glucanase [1] caused a drastic molecular downshift of 1,3 ; 1,4-beta-glucans. N-terminal amino acid sequences of glucanase [1] and [4] were determined. The sequence of glucanase [4] (30 AA residues) has a high homology to cDNA sequence of genomic DNA of rice (D40610). The sequence of glucanase [1] (five AA residues) is homorogous to cDNA expression tag of rice (D39445). The mucleotide sequence if 400 bp from 3' and 5' end of the D39445 cDNA were determined. These results serves as the basic knowledge for the future study on the regulation mechanism of auxin on cis element of the upstream of glucanase genes in elongation growth of cereal plants.