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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Sustainable Perennial Crops Laboratory » Research » Publications at this Location » Publication #370871

Research Project: Characterizing and Evaluating the Genetic Diversity and Horticultural Value of Genetic Resources for Cacao and Other Tropical tree crops Economically important to the United States

Location: Sustainable Perennial Crops Laboratory

Title: Foliar applied cuprous oxide fungicide induces physiological, biochemical and molecular changes in cacao leaves

Author
item SANTOS, SILVA - University Of Santa Cruz - Brazil
item ALMEIDA, A-A - University Of Santa Cruz - Brazil
item AHNERT, D - University Of Santa Cruz - Brazil
item SILVA, N - University Of Santa Cruz - Brazil
item SANTO, M - University Of Santa Cruz - Brazil
item SANTOS, N - University Of Santa Cruz - Brazil
item Baligar, Virupax

Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2020
Publication Date: 1/22/2020
Citation: Santos, S.J., Almeida, A.F., Ahnert, D., Silva, N.M., Santo, M.L., Santos, N.A., Baligar, V.C. 2020. Foliar applied cuprous oxide fungicide induces physiological, biochemical and molecular changes in cacao leaves. Scientia Horticulturae. 265:109224.

Interpretive Summary: Fungal diseases are affecting the sustainable production of Theobroma cacao in South America. To control fungal diseases multiple applications of copper-based fungicides are being used. High levels of copper can cause toxicity to the cacao plant. In this paper we report the effects of foliar applied cuprous oxide fungicide on the physiological, biochemical and molecular function of cacao leaves and showed how such changes affect the growth and development of cacao leaves. This information could lead to the development of novel fungicides with lower levels of copper thus reducing the toxic effect of this heavy metal on cacao growth. This information will be used by research and extension staff to improve cacao production.

Technical Abstract: Copper (Cu), besides being an essential micronutrient for plants, is a component of fungicides used in cacao farming. The objective of this study was to evaluate Cu toxicity in leaves of young plants of cocoa genotype CCN 51, applied via the leaf as cuprous oxide fungicide at different concentrations (0, 1.5, 3, 4.5 and 6 g Cu L-1) by means of physiological, biochemical, molecular and nutritional changes at leaf level. Cu concentrations (4.5 and 6 g Cu L-1) applied via leaf severely affected leaf gas exchange, promoted changes in the activity of APX, CAT, SOD and GPX enzymes, free proline content, lipid peroxidation and expression of the genes psbA, psbO, Mt2b, sod cyt, sod chl and per-1, as well as changes in content of mineral macro and micronutrients in leaf. It was concluded, therefore, that the application of different contents of Cu via cuprous oxide fungicide to leaf induced an imbalance in the leaf metabolism of the young plants of CCN 51, through modifications in leaf gas exchange, in the activity of the enzymatic and non-enzymatic antioxidative metabolism, in the expression of genes related to oxidative stress, photosynthesis and mechanisms of cellular detoxification. In addition, a dose- dependent type response pattern was verified, indicating that there was a synergism in the cellular detoxification pathways in eliminating excess reactive oxygen species (ROS).