PRE-GERMINATION AND CATECHOLASE (PPO) ACTIVITY IN PHASEOLUS LUNATUS WHOLE SEED, TESTA AND TESTA STRATA

摘要

The paper characterizes pre-germination behavior and catecholase (PPO) activity in mature seeds, seed testa and several laboratory separated seed testa strata of Phaseolus lunatus. Imbibition coefficients were 1.56 for whole seeds, 3.14 for whole testa, 2.6 for exotesta, 3.25 for meso and endotesta, 3.9 for mesotesta and 2.54 for endotesta. Enzymatic activity was measured polarographically. Catecholase activity was clearly deatectable and measured in all samples. The lowest activity was in whole seedwith the total testa (11.0 nmol O-2 h~1 gdm~(-1)) and highest in the separated total testa (743.0 nmol 0-2 h~(-1) gdm~(-1)). Separation of the testa strata showed differences in catecholase activity in the different strata (397.3 nmol 0-2 h~(-1) gdm~(-1) in exotesta, 155.5 nmol O-2h~(-1)gdm~(-1) in meso and endotesta combined, but 119.7 nmol O-2h~(-1_gdm~(-1) in the separated mesotesta and only 35.0 nmol 0-2h~(-1) gdm~(-1) in the separated endotesta). The novel contribution of the present paper is theanalysis of the relative contribution of different testa subtractions to the pool of catecholase activity, indicating that catecholase activity in whole seed is lower than in testa. The variations in catecholase activity were relatively large. The results demonstrate the functional role of catecholase and can be used in plant breeding and plant biotechnologies to promote immunity and germination.