The Class III peroxidases (CIII Prxs) belong to a plant-specific multigene family. Thanks to their double catalytic cycle they can oxidize compounds or release reactive oxygen species (ROS). They are either involved in different cell wall stiffening processes such as lignification and suberization, in cell wall loosening or defense mechanisms. Germination is an important developmental stage requiring specific peroxidase activity. However, little is known about which isoforms are involved. Five CIII Prx encoding genes: AtPrx04, AtPrx16, AtPrx62, AtPrx69, and AtPrx71 were identified from published microarray data mining. Delayed or induced testa and endosperm rupture were observed for the corresponding CIII Prx mutant lines indicating either a gene-specific inducing or repressing role during germination, respectively. Via in situ hybridization AtPrx16, AtPrx62, AtPrx69 and AtPrx71 transcripts were exclusively localized to the micropylar endosperm facing the radicle, and transcriptomic data analysis enabled positioning the five CIII Prxs in a co-expression network enriched in germination, cell wall, cell wall proteins and xyloglucan hits. Evidence were produced showing that the five CIII Prxs were cell wall-targeted proteins and that the micropylar endosperm displayed a complex cell wall domain topochemistry. Finally, we drew a spatio-temporal model highlighting the fine sequential gene expression and the possible involvement of micropylar endosperm cell wall domains to explain the non-redundant cell wall stiffening and loosening functions of the CIII Prxs in a single cell type. We also highlighted the necessity of a peroxidase homeostasis to accurately control the micropylar endosperm cell wall dynamics during Arabidopsis germination events.

中文翻译：

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拟南芥早期萌发事件中五个 III 类过氧化物酶编码基因的协调

III 类过氧化物酶 (CIII Prxs) 属于植物特异性多基因家族。由于它们的双催化循环，它们可以氧化化合物或释放活性氧 (ROS)。它们要么参与不同的细胞壁硬化过程，如木质化和木栓化，要么参与细胞壁松散或防御机制。萌发是一个重要的发育阶段，需要特定的过氧化物酶活性。然而，对于涉及哪些同工型知之甚少。从已发表的微阵列数据挖掘中鉴定了五个 CIII Prx 编码基因：AtPrx04、AtPrx16、AtPrx62、AtPrx69 和 AtPrx71。对于相应的 CIII Prx 突变系，观察到延迟或诱导的种皮和胚乳破裂，分别表明在萌发过程中具有基因特异性诱导或抑制作用。通过原位杂交 AtPrx16、AtPrx62、AtPrx69 和 AtPrx71 转录物仅定位于面向胚根的珠孔胚乳，转录组学数据分析能够将五个 CIII Prx 定位在富含萌发、细胞壁、细胞壁蛋白和木葡聚糖命中。产生的证据表明五个 CIII Prxs 是细胞壁靶向蛋白质，并且珠孔胚乳显示出复杂的细胞壁结构域拓扑化学。最后，我们绘制了一个时空模型，突出了精细的序列基因表达和珠孔胚乳细胞壁结构域的可能参与，以解释单个细胞类型中 CIII Prxs 的非冗余细胞壁硬化和松弛功能。