One irreversible consequence of acidic pH for roots is cell death. Growing evidence suggests the role of hormones and cell wall-related enzymes in response to acidic pH that could possibly avoid cell mortality. Here, we have investigated the role of ethylene and class III peroxidases (CIII Prxs) activity on sensitivity to further low pH treatment. Seedlings of Arabidopsis thaliana were pretreated with ethylene, at various concentrations for various times, and then exposed to low pH. In contrast to non-treated roots, roots pretreated with ethylene for 3 h became tolerant to subsequent low pH, with negligible cell mortality in meristematic (MZ), transition (TZ), and early elongation (EZ) zones. This effect of ethylene was time dependent since it was achieved only when seedlings were pre-incubated with ethylene for at least 3 h. This tolerance induced by ethylene was not observed in the gain-of-function mutation etr1-1 (insensitive to ethylene 1–1). Besides, it was prevented by salicylhydroxamic acid (SHAM) which is an inhibitor of CIII Prxs activity. In late EZ, the decrease in cell expansion due to low pH was dependent on both ethylene signaling and a SHAM-sensitive process. The responses mediated by ethylene signaling might involve CIII Prxs-dependent cell wall modifications, leading to tolerance to low pH and arrest in cell expansion during stress.

中文翻译：

---

导致拟南芥根耐受低 pH 胁迫的乙烯信号与 III 类过氧化物酶活性有关

根的酸性 pH 值的一种不可逆转的后果是细胞死亡。越来越多的证据表明激素和细胞壁相关酶在响应酸性 pH 值方面的作用可能避免细胞死亡。在这里，我们研究了乙烯和 III 类过氧化物酶 (CIII Prxs) 活性对进一步低 pH 处理的敏感性的作用。拟南芥幼苗用不同浓度的乙烯预处理不同时间，然后暴露于低 pH 值。与未经处理的根相反，用乙烯预处理 3 小时的根变得能够耐受随后的低 pH 值，在分生组织 (MZ)、过渡 (TZ) 和早期伸长 (EZ) 区的细胞死亡率可以忽略不计。乙烯的这种作用是时间依赖性的，因为它只有在幼苗与乙烯预孵育至少 3 小时时才能实现。在功能获得性突变 etr1-1（对乙烯 1-1 不敏感）中未观察到由乙烯诱导的这种耐受性。此外，它被水杨基异羟肟酸 (SHAM) 阻止，它是 CIII Prxs 活性的抑制剂。在 EZ 后期，由于低 pH 值导致细胞扩增的减少取决于乙烯信号传导和 SHAM 敏感过程。乙烯信号介导的反应可能涉及 CIII Prxs 依赖性细胞壁修饰，导致对低 pH 的耐受性和应激期间细胞扩张停滞。由于低 pH 值导致细胞扩增的减少取决于乙烯信号传导和 SHAM 敏感过程。乙烯信号介导的反应可能涉及 CIII Prxs 依赖性细胞壁修饰，导致对低 pH 的耐受性和应激期间细胞扩张停滞。由于低 pH 值导致细胞扩增的减少取决于乙烯信号传导和 SHAM 敏感过程。乙烯信号介导的反应可能涉及 CIII Prxs 依赖性细胞壁修饰，导致对低 pH 的耐受性和应激期间细胞扩张停滞。