Defense dynamics in walnut (Juglans regia L.) fruit during walnut husk fly (Rhagoletis completa Cresson) infestation : an integrative, multi-level analysis

Grohar, Mariana Cecilia (author), Zamljen, Tilen (author), Medič, Aljaž (author), Šimkova, Kristyna (author), Burin, Tea (author), Vidrih, Rajko (author), Veberič, Robert (author)

The walnut husk fly (WHF) is a critical pest affecting global walnut production, causing economic losses of up to 80%. WHF larvae feed within the walnut husk, creating necrotic spots, which compromise kernel quality and marketability. In this research, the metabolic response of the walnut fruit was addressed for the first time in an integrative, multi-level analysis, which included several primary and secondary metabolites, enzymes, and antioxidant activities by using LC-MS, GC-MS, and different spectrophotometric methods. Results revealed localized and tissue-specific metabolic responses, with significant changes up to 200% in volatiles and phenolics, especially naphthoquinones and sesquiterpenes, as well as enzyme activities. Additionally, prolonged infestations severely affected kernel quality by reducing the content of unsaturated fatty acids and carotenoids by 60–70%, potentially due to oxidative stress and arrested fruit growth. Understanding these defense mechanisms is essential to mitigate economic losses and food waste, ensuring sustainable walnut production through targeted interventions and improved pre- and post-harvest treatments. They are also fundamental for future decisions on pheromone-based management of WHF, as well as for breeding efforts or pest control programs oriented to the enhancement of the natural plant defense mechanisms.

• Language: English
• Keywords: sugars, fatty acids, kernel, husk, phenolics, volatiles
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 16 str.
• Numbering: Vol. 25, art. 1531
• PID: 20.500.12556/RUL-175874
• UDC: 634.5
• ISSN on article: 1471-2229
• DOI: 10.1186/s12870-025-07552-0
• COBISS.SI-ID: 256795139
• Publication date in RUL: 12.11.2025

Record is a part of a journal

• Title: BMC plant biology
• Shortened title: BMC plant biol.
• Publisher: BioMed Central
• ISSN: 1471-2229
• COBISS.SI-ID: 2594324

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.

Secondary language

• Language: Slovenian
• Keywords: oreh, škodljivci rastlin, Rhagoletis completa, okužba, obramba rastline, sladkorji, maščobne kisline, fenolne spojine

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: Z4-50136
• Name: Metabolomika interakcij med rastlino in patogenom v orehih: večstranski pristop k vplivu bakterijske črne pegavosti ter orehove muhe na plod in olje.

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P4-0013
• Name: Hortikultura