Understanding the germination and post-germination from the peptidases metabolism in Parkia multijuga Benth.: an Amazonian dominant legume tree species

Enzymes are pivotal molecules orchestrating seed germination and metabolism, regardless of plant species. Peptidases are particularly important to the advancement of the germination process since their catalytic diversity ensures a nitrogen source for seedling establishment through extensive hydrolysis of storage proteins. This study aimed to investigate the peptidase activity and occurrence of peptidase inhibitors through different stages of the seed germination and seedling establishment of an Amazonian dominant legume tree species. The enzyme activities were measured in quiescent seeds (QS); after imbibition (IS), radicle protrusion (PR), expansion of the cotyledon node (ECN), and the emergence of the shoots (ES) corresponding to days 0, 1, 5, 8 and 12 days, after imbibition, respectively. The protein content reduction was observed from PR on. The breakdown of storage proteins reached the maximum at ES as measured by proteolysis. The inhibition of trypsin, papain, and bromelain was consistent throughout, increasing in ES. Inhibitors, with trypsin-like features, were observed at all stages studied. Thus, inhibitors of serine and cysteine peptidases may be involved in the regulation of proteolysis during the seed germination and post-germination of Parkia multijuga. Our findings reveal the critical role of the peptidases and peptidase inhibitors during seed germination, as well as the potential applications in research aimed at improved plant defense.