Plant growth regulators induced urease activity in Cucurbita pepo L. cotyledons

What is it about?

This study is aimed to investigate the activity of urease (EC 3.5.1.5, urea amidohydrolase) that catalyzes the hydrolysis of urea in 5-day-old Cucurbita pepo cotyledons subjected to various concentrations of different growth regulators. The treatment of C. pepo cotyledons with different concentrations (100–600 μmol) of different auxins [indole-3-acetic acid (IAA), indole butyric acid (IBA), indole propionic acid (IPA) and naphthalene acetic acid (NAA)]; or with different concentrations (100–300 μmol) of different cytokinins [kinetin, zeatin and benzyladenine (6-BA)] resulted in a significant increase of urease activity, compared to control. The optimal effects were recorded for each of 500 μmol of IAA and 300 μmol of zeatin treatments. A gradual increase in urease activity was detected in cotyledons treated with various concentrations (0.2–1.0 mM) of 28-homobrassinolide (HBL), in relative to control. A substantial increase in urease activity was observed in cotyledons subjected to different concentrations of triazole (10–60 mg L–1), containing either triadimefon (TDM) or hexaconazole (HEX), compared to control. The combination of 300 μmol zeatin with any of protein inhibitors, namely 5-fluorouridine (FUrd), cordycepin and α-amanitin, resulted in the alleviation of their inhibitory effect on the urease activity.

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Why is it important?

phytohormones [auxins (IAA, IBA, IPA and NAA); cytokinins (kinetin, zeatin and 6-BA); HBL; triazole (TDM and HEX)] stimulated the urease activity in 5-day-old C. pepo cotyledons. The greatest increase in urease activity in response to phytohormones was recorded in 500 μmol IAA and in 300 μmol zeatintreated cotyledons. Combination each of FUrd, cordycepin and α-amanitin with 300 μmol zeatin resulted in high amelioration of their inhibitory effects on urease activity. Combination of zeatin with cordycepin was the best, whereas it resulted in increasing the relative activity from 53.5% up to 206.3%.

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