Purine degradation products have been shown to play roles in plant response to stresses such as drought, salinity, extended dark, nitrogen deficiency, and pathogen infection. In this study, we used Arabidopsis wild-type (WT) and an Atxdh1-knockout mutant defective in xanthine dehydrogenase1 (XDH1) to examine the role of degraded purine metabolites in the responses to wounding or UV-C stress applied to the middle leaves of the plant. Wounding or UV-C stress in the mutant resulted in lower fresh-weight, increased senescence symptoms, and increased cell death compared to WT plants. In addition, WT plants exhibited lower levels of oxidative stress indicators, reactive oxygen species, and malondialdehyde in their leaves than the mutant. Notably, transcripts and proteins functioning in the purine degradation pathway were regulated in such a way that it led to enhanced ureide levels in WT leaves 24h after applying the UV-C or wound stress. However, different remobilization of the accumulated ureides was observed after 72h of stress. In plants treated with UV-C, the concentration of allantoin was highest in young leaves, whereas in wounded plants it was lowest in these leaves and instead accumulated mainly in the middle leaves that had been wounded. These results indicated that in WT plants treated with UV-C, ureides were remobilized from the lower older and damaged leaves to support young leaf growth during the recovery period from stress. After wounding, however, whilst some ureides were remobilized to the young leaves, more remained in the wounded middle leaves to function as antioxidants and/or healing agents.

中文翻译：

---

拟南芥叶片对 UV-C 照射和伤害的反应类似地积累脲，但在恢复过程中重新动员的方式不同

嘌呤降解产物已被证明在植物对干旱、盐度、延长黑暗、缺氮和病原体感染等胁迫的反应中发挥作用。在这项研究中，我们使用拟南芥野生型 (WT) 和黄嘌呤脱氢酶 1 (XDH1) 缺陷的 Atxdh1 敲除突变体来检查降解的嘌呤代谢物在对施加于中叶的伤害或 UV-C 应激反应中的作用。植物。与野生型植物相比，突变体中的伤口或 UV-C 应激导致鲜重降低、衰老症状增加和细胞死亡增加。此外，与突变体相比，野生型植物叶片中的氧化应激指标、活性氧和丙二醛水平较低。尤其，在嘌呤降解途径中起作用的转录物和蛋白质受到调节，使其在施加 UV-C 或伤口应激后 24 小时导致 WT 叶中的脲水平升高。然而，在压力 72 小时后，观察到积累的脲的不同再活化。在用 UV-C 处理的植物中，幼叶中尿囊素的浓度最高，而在受伤的植物中，这些叶子中的尿囊素浓度最低，而是主要在受伤的中间叶片中积累。这些结果表明，在用 UV-C 处理的 WT 植物中，脲从较低的较老和受损的叶子中重新活化，以在从胁迫恢复期间支持幼叶生长。然而，在受伤后，虽然一些尿素被重新激活到幼叶上，