Differential influence of herbicide treatments on activity and kinetic parameters of C4 photosynthetic enzymes from Zea mays

摘要: Abstract The recommended field dose of rimsulfuron, imazethapyr, alachlor, atrazine or fluometuron differentially reduced shoot fresh and dry weight 10-day-old maize seedlings as well leaf protein content during the following 12 days. These reductions seemed consistent whole period with fluometuron, alachlor but appeared to be nullified by 5th day treatment rimsulfuron imazethapyr. On other hand, all herbicides mostly provoked significant inhibitions in specific activities phospho enol pyruvate carboxylase (PEPC, EC 4.1.1.31), malate dehydrogenase (MDH, 1.1.1.82), phosphate dikinase (PPDK, 2.7.9.1) ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, 4.1.1.39) leaves first 2 Thereafter, inhibition was recovered samples treated leveled off consistently augmented fluometuron. kinetic characterization showed that imazethapyr unchanged V max enzymes vitro, however, PEPC, PPDK Rubisco were decreased vivo. Nevertheless, substantially while a reduction this value MDH Rubisco. Thus atrazine, and, lower extent, concentrations for only contrary, K m values progressively increased indicating different altered structural integrity enzymes. findings conclude competitively inhibited revealed mixed Atrazine whereas either competitive inhibitor