Rains Meghan K, Caron Christine, Regan Sharon, Molina Isabel
Department of Biology, Algoma University, Sault Ste. Marie, ON P6A 2G4, Canada.
Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada.
Plants (Basel). 2022 Apr 22;11(9):1143. doi: 10.3390/plants11091143.
Upon mechanical damage, plants produce wound responses to protect internal tissues from infections and desiccation. Suberin, a heteropolymer found on the inner face of primary cell walls, is deposited in specific tissues under normal development, enhanced under abiotic stress conditions and synthesized by any tissue upon mechanical damage. Wound-healing suberization of tree bark has been investigated at the anatomical level but very little is known about the molecular mechanisms underlying this important stress response. Here, we investigated a time course of wound-induced suberization in poplar bark. Microscopic changes showed that polyphenolics accumulate 3 days post wounding, with aliphatic suberin deposition observed 5 days post wounding. A wound periderm was formed 9 days post wounding. Chemical analyses of the suberin polyester accumulated during the wound-healing response indicated that suberin monomers increased from 0.25 to 7.98 mg/g DW for days 0 to 28, respectively. Monomer proportions varied across the wound-healing process, with an overall ratio of 2:1 (monomers:glycerol) found across the first 14 days post wounding, with this ratio increasing to 7:2 by day 28. The expression of selected candidate genes of poplar suberin metabolism was investigated using qRT-PCR. Genes queried belonging to lipid polyester and phenylpropanoid metabolism appeared to have redundant functions in native and wound-induced suberization. Our data show that, anatomically, the wounding response in poplar bark is similar to that described in periderms of other species. It also provides novel insight into this process at the chemical and molecular levels, which have not been previously studied in trees.
受到机械损伤后，植物会产生创伤反应以保护内部组织免受感染和脱水。木栓质是一种存在于初生细胞壁内表面的杂聚物，在正常发育过程中沉积于特定组织中，在非生物胁迫条件下会增加，并且在受到机械损伤时任何组织都会合成。树皮伤口愈合的木栓质化过程已在解剖学水平上进行了研究，但对于这种重要应激反应背后的分子机制知之甚少。在此，我们研究了杨树树皮创伤诱导木栓质化的时间进程。显微镜观察结果表明，多酚类物质在受伤后3天积累，受伤后5天观察到脂肪族木栓质的沉积。受伤后9天形成了创伤周皮。对伤口愈合反应过程中积累的木栓质聚酯进行化学分析表明，从第0天到第28天，木栓质单体分别从0.25毫克/克干重增加到7.98毫克/克干重。单体比例在伤口愈合过程中有所变化，在受伤后的前14天，单体与甘油的总体比例为2:1，到第28天时该比例增加到7:2。使用qRT-PCR研究了杨树木栓质代谢中选定候选基因的表达。属于脂质聚酯和苯丙烷类代谢的查询基因似乎在天然和创伤诱导的木栓质化中具有冗余功能。我们的数据表明，在解剖学上，杨树树皮的创伤反应与其他物种周皮中描述的相似。它还在化学和分子水平上为这一过程提供了新的见解，而此前在树木中尚未对此进行过研究。
