In plants, root hairs undergo a highly-polarized form of cell expansion called tip-growth, in which cell wall deposition is restricted to the root hair apex. In order to identify essential cellular components that might have been missed in earlier genetic screens we identified conditional temperature sensitive (ts) root hair mutants by EMS mutagenesis. Here we describe one of these mutants, fer-ts (feronia-temperature sensitive). Mutant fer-ts seedlings grew normally at normal temperatures (20˚C), but failed to form root hairs at elevated temperatures (30˚C). Map based-cloning and whole genome sequencing revealed that fer-ts resulted from a G41S substitution in the extracellular domain of FERONIA (FER). A functional fluorescent fusion of FER containing the fer-ts mutation localized to plasma membranes, but was subject to enhanced protein turnover at elevated temperatures. While tip-growth was rapidly inhibited by addition of RALF1 peptides in both wild-type and fer-ts mutants at normal temperatures, root elongation of fer-ts seedlings was resistant to added RALF1 peptide at elevated temperatures. Additionally, at elevated temperatures fer-ts seedlings displayed altered ROS accumulation upon auxin treatment and phenocopied constitutive fer mutant responses to a variety of plant hormone treatments. Molecular modeling and sequence comparison with other CrRLK1L receptor family members revealed that the mutated glycine in fer-ts is highly conserved, but is not located in the recently characterized RALF23 and LORELI-LIKE-GLYCOPROTEIN (LLG2) binding domains, perhaps suggesting that fer-ts phenotypes may not be directly due to loss of binding to RALF1 peptides.

中文翻译：

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fers的功能表征，温度敏感的FERONIA突变等位基因，可改变根毛的生长

在植物中，根毛会经历高度极化的细胞扩张形式（称为尖端生长），其中细胞壁的沉积仅限于根毛的顶端。为了鉴定在早期遗传筛选中可能遗漏的必需细胞成分，我们通过EMS诱变鉴定了条件温度敏感（ts）根毛突变体。在这里，我们描述了这些突变体之一，fer-ts（对温度敏感的feronia）。突变型蕨类植物幼苗在正常温度（20°C）下正常生长，但在高温（30°C）下未能形成根毛。基于图谱的克隆和全基因组测序表明，fer-ts是由FERONIA（FER）胞外域中的G41S取代产生的。包含功能定位于质膜的fer-ts突变的FER的功能性荧光融合体，但在升高的温度下会增加蛋白质更新。虽然在正常温度下在野生型和fer-ts突变体中通过添加RALF1肽均可迅速抑制叶尖生长，但在高温下，fer-ts幼苗的根部伸长对添加的RALF1肽具有抗性。另外，在高温下，肥育苗在生长素处理后表现出改变的ROS积累，并且对多种植物激素处理表现出表型组成型Fer突变。分子建模和与其他CrRLK1L受体家族成员的序列比较显示，fer-ts中的突变甘氨酸是高度保守的，但不在最近鉴定的RALF23和LORELI-LIKE-糖蛋白（LLG2）结合域中，