Ethylene causes the accumulation of seven different
proteins (each designated AZxx according to its molecular mass, xx in kD) in excised primary leaves of azuki bean (Vigna angularis) (F. Ishige, H. Mori, K. Yamazaki, H. Imaseki [1991] Plant Cell Physiol 32: 681-690). A
complementary DNA encoding an
ethylene-induced basic
glycoprotein, AZ42, from azuki bean was cloned and its complete nucleotide sequence was determined. Characterization of the
cDNA was accomplished by monitoring expression of an immunoreactive
protein in Escherichia coli that harbored the
cDNA and by the identification of a partial amino acid sequence that was the same as that determined from the purified
protein. An open reading frame (1071 base pairs) in the
cDNA encoded a
protein of 357
amino acids with a molecular mass of 39.3 kD. The amino acid sequence contained three regions that are highly conserved among
peroxidases from eight different plants. Purified AZ42 exhibited
peroxidase activity. The basic
glycoprotein induced by
ethylene was identified as a cationic
isozyme of
peroxidase. The corresponding
mRNA was not present in leaves that had not been treated with
ethylene, but it appeared after 1 h of treatment with
ethylene and its level increased for the next 15 h. Accumulation of the
mRNA was also induced after wounding or treatment with
salicylate. The
wound-induced increase in the level of the
mRNA was suppressed by
2,5-norbornadiene, but the
salicylate-induced increase was not.