Department of Basic Science, Faculty of Animal Science and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.
Department of Biology, Faculty of Sciences, Golestan University, Gorgan, Iran.
Plant Physiol Biochem. 2019 Nov;144:264-273. doi: 10.1016/j.plaphy.2019.09.047. Epub 2019 Sep 30.
Iron (Fe) as a micronutrients and silicon (Si) as a cell wall element are important in plant cell wall extension and integrity. While the interaction of exogenous Si and excess Fe on root cell wall modifications is known, the effects of these nutritional parameters on the spatial changes in the activities of genes and/or enzymes involved in the lignification of root cell walls are not well studied. Thus, these parameters were investigated in the root apical part (AP) and basal part (BP) of rice (Oryza sativa L.) plants supplied with and without Si (1.5 mM) under normal (10 mg/L) and excess Fe (150 mg/L) nutrition for 7 days. Beside growth retardation, excess Fe increased the activities of phenylalanine ammonia lyase (PAL), superoxide dismutase and NADPH-oxidase and PAL and cell wall peroxidase (POD) genes expression, along with the increased phenols and HO contents in the root AP. Furthermore, the increased thickening of endodermal, exodermal and metaxylem cell walls in the root AP by excess Fe was attributed to the enhanced POD activity. POD expression, endodermal and exodermal cell wall thickenings were not affected by excess Fe in the root BP. Si application under excess Fe exaggerated the effects of excess Fe on root cell wall thickening, increased POD activity but reduced HO content in the root AP. Thus, Si application under excess Fe nutrition promotes earlier initiation of lignin polymerization closer to and toward the root tip and hence restricts the entry of excess Fe into the plant.
铁（Fe）作为一种微量元素和硅（Si）作为细胞壁元素，对于植物细胞壁的延伸和完整性非常重要。虽然外源 Si 和过量 Fe 对根细胞壁修饰的相互作用是已知的，但这些营养参数对参与根细胞壁木质化的基因和/或酶的活性在空间上的变化的影响尚未得到很好的研究。因此，在正常（10mg/L）和过量 Fe（150mg/L）营养条件下，研究了这些参数在水稻（Oryza sativa L.）根顶端（AP）和基部（BP）中的作用，分别有无 Si（1.5mM）供应 7 天。除了生长迟缓外，过量 Fe 还增加了苯丙氨酸解氨酶（PAL）、超氧化物歧化酶和 NADPH 氧化酶的活性，以及 PAL 和细胞壁过氧化物酶（POD）基因的表达，同时增加了根 AP 中的酚类和 HO 含量。此外，过量 Fe 引起的根 AP 内皮层、外表皮和木质部细胞细胞壁的增厚归因于 POD 活性的增强。过量 Fe 对根 BP 中的 POD 表达、内皮层和外表皮细胞壁增厚没有影响。在过量 Fe 下施 Si 夸大了过量 Fe 对根细胞壁增厚的影响，增加了 POD 活性，但降低了根 AP 中的 HO 含量。因此，在过量 Fe 营养下施 Si 促进了木质素聚合的更早启动，更接近和朝向根尖，从而限制了过量 Fe 进入植物。
