Betacyanin accumulation and guaiacol peroxidase activity in Beta vulgaris L. leaves following copper stress

Abstract

The effect of copper stress on betacyanin accumulation and guaiacol peroxidase (GPOD) activity in leaves of different age was evaluated in red beet (Beta vulgaris L. var. Crosby Egyptian) plants. In hydroponic culture, plants were treated with 0.3 μM (control), 50 μM, 100 μM, and 250 μM of CuSO 4 for 6 days. Copper was taken up and accumulated in old roots but was not translocated to leaves. However in young leaves, the increase of lipid peroxidation and reduction of growth were evident from day 3 of copper exposure; whereas in old leaves, the lipid peroxidation and growth were the same from either copper-treated or control plants. In response to copper exposure, the betacyanin accumulation was evident in young leaves by day 3, and continued to increase until day 6. Betacyanin only were accumulated in old leaves until day 6, but the contents were from 4 to 5 times lower than those observed in young leaves at the same copper concentrations. GPOD activity increased 3.3-and 1.4-fold in young and old leaves from day 3 of copper treatment respectively, but only in the young leaves was sustained at the same level until day 6. Old roots shown betacyanin in the control plants, but the betacyanin level and growth were reduced with the copper exposure. In contrast, young roots emerged by copper effect also accumulated copper and showed the highest betacyanin content of all plant parts assayed. These results indicate that betacyanin accumulation and GPOD activity are defense responses to copper stress in actively growing organs.

The Impact of Copper Ions on Oxidative Stress in Garden Cress Lepidium sativum

“…In addition, it was observed, that induction of GPOX activity in copper-treated plants of Beta vulgaris L. was higher in young leaves than in old leaves [28]. The high activity of guaiacol peroxidase in Lepidium sativum shoots treated by the highest dose of Cu 2+ suggest resistance of this plants to copper stress.…”

“…Increases in the level of MDA have been found in plants treated with copper such as Eichornia crassipes [29], Potamogeton pusillus [30], Hydrilla verticillata [17], Spirodela polyrhiza [4], Brassica juncea [23], Astragalus neo-mobayenii [26], Beta vulgaris [28], Allium sativum [27] and Solanum nigrum [31].…”

Are betalain pigments the functional homologues of anthocyanins in plants?

“…Betalains are also known to complex with metal ions such as Cu 2+ and Hg 2+ (Herbach et al, 2006), and betalain biosynthesis is upregulated in response to Co 2+ , Mo 2+ , Fe 2+ and Cu 2 + (León Morales et al, 2012;Perotti et al, 2010;Trejo-Tapia, 2001); however, the possibility of a functional role of betalains in metal stress tolerance has never been evaluated. Similarly, it is not known if foliar betalains are involved in herbivore deterrence.…”

Plant betalains: Chemistry and biochemistry

“…In addition to IAA, it appears that 2,4-D too has a regulatory effect on TYR as its concentration in culture medium was linked to enzyme activity. TYR activity may increase in the presence of Cu 2+ thereby increasing betalain biosynthesis (Morales et al, 2012). Moreover, DO activity associated with TYR corresponded to betalain content in different tissues of A. hypochondriacus (Casique-Arroyo et al, 2014).…”