Nitric oxide enhances rooting of Pendolino olive cuttings by upregulating CAT, POD, and PPO activities while suppressing IAA oxidase, phenols and total sugars

Omar Thaer Kamil; Ahmed Adnan Mohammed; Ahmed Abdelhady Rashedy; Wael Mohamed Eldeeb; Hamed Hosny Hamed<sup>2; 4 </sup>

ISSN: 0972-1045

Nitric oxide enhances rooting of Pendolino olive cuttings by upregulating CAT, POD, and PPO activities while suppressing IAA oxidase, phenols and total sugars

Journal of Applied Horticulture, 2025, 27(3): 524-530.

Nitric oxide enhances rooting of Pendolino olive cuttings by upregulating CAT, POD, and PPO activities while suppressing IAA oxidase, phenols and total sugars

Omar Thaer Kamil¹, Ahmed Adnan Mohammed¹, Ahmed Abdelhady Rashedy²*, Wael Mohamed Eldeeb³ and Hamed Hosny Hamed^2,4

¹Department of Medicinal and Industrial Plants, College of Medicinal and Industrial Plants, University of Kirkuk, Kirkuk, Iraq. ²Pomology Department, Faculty of Agriculture, Cairo University, Giza, Egypt. ³Energy and Environment Research Center, Tabbin Institute for Metallurgical Studies, Egypt. ⁴Organic Crop Production Department, Faculty of Organic Agriculture, Heliopolis University, Egypt.Corresponding e-mail: ahmed.rasheedy@agr.cu.edu.eg

DOI: https://doi.org/10.37855/jah.2025.v27i03.95

Key words: Olea europaea, phenol, sugars, CAT, POD, IAAox, PPO, indole

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Abstract:

Vegetative propagation is crucial for maintaining genetic integrity in the production of commercial olive planting material. However, poor rooting makes it difficult to grow cuttings from specific varieties. Nitric oxide (NO), a signalling molecule that has been shown to enhance root initiation in various plant species, may help overcome this barrier. This study evaluated the effect of nitric oxide (NO) at concentrations of 0, 50, 100, 500, 1000, 2000, 4000, and 8000 µM on the rooting of Pendolino olive cuttings. NO at 100 µM produced the highest rooting percentage (52.24%), number of roots (10.8), and root length, alongside significant increases in catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO) activities, and a marked reduction in indole-3-acetic acid oxidase (IAAox) activity. In comparison to the control (0 µM NO + 4000 ppm IBA), 100 µM NO elevated CAT, POD, and PPO activities by 52%, 85.22%, and 88.51%, respectively, while reducing IAAox by 44%. At this concentration, NO also decreased total phenols by 9.14%. The dose-dependent pattern of the effect of NO concentration on roots could be distinguished. Rooting was significantly inhibited by the highest concentration of NO (8000 µM). These results indicate that neither suboptimal nor supraoptimal NO concentration can promote effective adventitious rooting, highlighting the importance of a precise concentration range for improved rooting in challenging olive cultivars.