Ascorbic Acid Oxidase Activity in Apple Buds: Relation to Thidiazuron-induced Lateral Budbreak

Abstract

<jats:p>The activity of ascorbic acid oxidase (AAO) was studied in apple <jats:italic>(Malus domestica</jats:italic> Borkh.) buds during dormancy and thidiazuron-induced budbreak. In dormant buds, activity of AAO was low compared with buds that were treated with thidiazuron and had resumed growth. An increase in AAO activity began at the time of metabolic transition from dormancy to budbreak. The highest level of activity was reached 10 days after thidiazuron induction during the expansion growth phase. In vitro AAO activity of apple bud extract was increased by addition of Cu (CuSO) and inhibited by Cu-chelating agents, diethyldithiocarbamate (DDC), sodium azide (NaN), and 8-hydroxyquinoiine (8-OH-Q). In vivo treatment of apple buds with Cu-chelating agents inhibited AAO activity and bud growth but not budbreak. Chemical name used: <jats:italic>N-</jats:italic> phenyl <jats:italic>-N'</jats:italic> -1,2,3-thidiazol-5-ylurea (thidiazuron).</jats:p>

Response of pepper leaves epidermal cell under ozone stress to ascorbic acid treatment

“…This result agrees to a certain extent with the findings of Ali (2001), Ali et al (2015), and Hendi and Boghdady (2016), where they reported that AS induces some anatomical changes in the plants. In addition, the present result was in conformity with the results of previous studies, which reported that AS plays a role in the expansion and elongation of the cells (Padh, 1990;Wang and Faust, 1992;De Gara et al, 1996;Smirnoff and Pallanca, 1996;Tommasi et al, 1999;Horemans et al, 2000;Kaviani, 2014;Cavusoglu and Bilir, 2015).…”

Changes in the Antioxidant System Associated with Budbreak in `Anna' Apple (Malus domestica Borkh.) Buds

“…These treatments also increased the ratios of ascorbate : dehydroascorbate and GSH : GSSG and activities of AFR, ascorbate peroxidase, DHAR, ascorbate oxidase, and GR. Based on recent studies (Wang and Faust, 1992;Wang et al, 1991a-d) and the results presented here, a proposed scheme of ascorbate-glutathione cycle associated with budbreak for removing free radicals in apple buds is summarized in Fig. 6.…”

“…The enzymes associated with peroxidase scavenging systems are AFR, ascorbate peroxidase, DHAR, and ascorbate oxidase. The activities of these enzymes increased when budbreak was induced by hot water, cold temperature, allyl disulfide (Tables 1 and 2), or thidiazuron (Wang and Faust, 1992;Wang et al, 1991a). 1.9 ± 0.5 6.9 ± 1.1 5.1 ± 0.9 5.3 ± 0.9 Dehydroascorbate [µmol (g dry wt)] 0.9 ± 0.1 0.5 ± 0.1 0.…”

“…The concurrent increase in the concentration of ascorbate and the activities of AFR, DHAR, ascorbate peroxidase, and ascorbate oxidase during the induction of budbreak in paradormant or endodormant buds by treatment with high or low temperatures or by allyl disulfide indicates that an increased capacity for free-radical scavenging is associated with budbreak. AAO is largely localized in the cell walls of apple buds (Wang and Faust, 1992). High AAO activity is characteristic of diverse, actively growing tissue (Newcomb, 1951).…”