20.500.12556/RUL-176050 Effects of Xanthomonas arboricola pv. juglandis on walnut fruit insights into the tissue-specific metabolic response Walnut bacterial blight (WBB), caused by Xanthomonas arboricola pv. juglandis, is one of the most damaging diseases in walnut production, capable of reducing yields by up to 50%. Despite its economic importance, tissue-specific defense mechanisms in walnut fruit remain poorly understood. In this study, we performed an integrative approach with metabolomic and biochemical analyses of walnut fruit responses to WBB, examining primary and secondary metabolites, antioxidant activities, and enzyme dynamics across affected and non-affected tissues of the husk, stalk, as well as kernel pellicle and flesh. Using LC-MS, GC-MS, and spectrophotometric assays, we identified distinct compartmentalized defense strategies. The husk showed strong phenolic-mediated responses, with naphthoquinone levels increasing by 125%. However, oxidative processes in necrotic areas may have reduced the stability of these compounds by 50%. In contrast, affected kernel tissues exhibited lower phenolic activity, suggesting that carotenoids and fatty acids could be involved as a protection mechanism, undergoing early oxidation to help preserve lipid integrity. Antioxidant enzymes were upregulated in husk and kernel pellicle, while volatile terpenes and sugars accumulated in infected tissues, indicating metabolic shifts toward localized defense. Overall, our findings reveal a tissue-specific, multi-layered defense network in walnut fruit that could constitute specific markers associated with disease progression. walnut bacterial blight Juglans regia fatty acids kernel husk enzymes phenolics volatiles oreh škodljivci rastlin Xanthomonas arboricola pv. juglandis metabolni odziv fenoli maščobne kisline true false true Angleški jezik Slovenski jezik Članek v reviji 2025-11-19 12:54:11 2025-11-19 12:54:17 2025-12-17 04:06:19 0000-00-00 00:00:00 2025 0 0 14 str. iss. 11, art. 1391 Vol. 11 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 632 2311-7524 257806083 horticulturae-11-01391-v2.pdf horticulturae-11-01391-v2.pdf 1 33E4C5F3028797D1C8413EF4EBC693DB 497f5bcfeabb06598b550d24ba5571031ea362c2b5700ee45a9e8a7d093664cc 42ffc9e4-c53e-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=222116 https://www.mdpi.com/2311-7524/11/11/1391 1 2187cf5d-c53e-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=222115 Biotehniška fakulteta 0 0 0