Is juglone the only naphthoquinone in Juglans regia L. with allelopathic effects?

Medič, Aljaž (author), Zamljen, Tilen (author), Slatnar, Ana (author), Hudina, Metka (author), Veberič, Robert (author)

We investigated whether juglone is the only allelochemical in a leaf extract from the walnut (Juglans regia L.). This was achieved through comparisons of the effects of pure juglone (1 mM, 100 µM, 10 µM control juglone) and J. regia leaf extract (prepared as 1 mM, 100 µM leaf juglone) on seed germination, seedling growth, and secondary metabolism of the selected crop vegetables. Two control treatments were also applied, as extraction medium and water. For inhibition of seed germination, S. lycopersicum, B. rapa var. japonica, and V. locusta were more sensitive to 1 mM leaf juglone, and L. sativa was more sensitive to 1 mM control juglone. This suggests that this walnut leaf extract contains specific phenolic substance(s) that can stimulate seed germination in some species and inhibit it in others. Seedling length was more sensitive to 1 mM leaf juglone than 1 mM control juglone, with selective strong inhibition of root length versus shoot length by 1 mM control juglone. Juglone also had significant effects on the secondary metabolism of L. sativa, in particular for seedlings treated with 100 µM control juglone, with marked decreases in all secondary metabolites studied. Flavonols constituted the majority of these metabolites in L. culinaris, which showed the least sensitivity to both control juglone and leaf juglone treatments. Thirty compounds were identified and quantified in S. lycopersicum, L. culinaris, and L. sativa, some for the first time in these plants, and all for the first time in the seedlings of these crop vegetables.

• Language: English
• Keywords: juglone, naphthoquinones, allelopathy, Juglans regia L., leaf extract, Solanum lycopersicum L., Lens culinaris Medik., Lactuca sativa L., Brassica rapa L. var. japonica, Valerianella locusta Laterr.
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: 15 str.
• Numbering: Vol. 11, iss. 8, art. 784
• PID: 20.500.12556/RUL-136044
• UDC: 634.1/.7
• ISSN on article: 2077-0472
• DOI: 10.3390/agriculture11080784
• COBISS.SI-ID: 73312515
• Publication date in RUL: 08.04.2022

Record is a part of a journal

• Title: Agriculture
• Shortened title: Agriculture
• Publisher: MDPI
• ISSN: 2077-0472
• COBISS.SI-ID: 523634201

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 17.08.2021

Secondary language

• Language: Slovenian
• Keywords: Juglans regia, oreh, juglone, alelopatija, listni ekstrakt, sekundarni metaboliti, fenoli, kemična sestava

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P4-0013
• Name: Hortikultura