INDUCTION OF A GERMINATION SPECIFIC, LOW-MOLECULAR-WEIGHT, ACID-PHOSPHATASE ISOZYME WITH SPECIFIC PHOSPHOTYROSINE PHOSPHATASE-ACTIVITY IN LENTIL (LENS ESCULENTA) SEEDS

A germination specific isozyme of acid phosphatase (EC 3.1.3.2) hydrol ysing O-phospho-L-Tyrosine, pH optima 5.5 is induced in lentil seeds, When seeds at 0 h, 24 h and 36 h of germination are electrophorezed, n ative PAGE on specific enzyme staining shows several constitutive isoz ymes of acid phosphatases. At 48 h, an isozyme is induced which gradua lly decreases and then disappears at 108 h of germination. The short l ived, induced isozyme is present in the embryo and seed-coat but not i n the plumule and the radical. Induction of this isozyme is inhibited by cycloheximide and actinomycin-D and increased by plant growth regul ators such as heteroauxin and gibbrellic acid treatment during germina tion. The induced isozyme is a single 30 kD polypeptide, with subunit molecular mass of 25 kD, shows activity for O-phospho-L-Tyrosine. It i s strongly inhibited by vanadate (mu M), molybdate, tungustate as also by iodoacetate, p-chloromercuribenzoate and diethylpyrocarbonate. Thi s study shows for the first time that the germination induced low mole cular weight Acid phosphatase is a Tyrosine phosphatase super family c lass IV enzyme, having a role in cellular differentiation and developm ent during seed germination. (C) 1998 Academic Press.