Zhou Ying, Gu Tianyu, Gao Yan, Qu Jingtao, Zheng Hongjian, Guan Yuan, Peng Jiashi
School of Life and Health Sciences, Hunan University of Science and Technology, Xiangtan 411201, China.
CIMMYT-China Specialty Maize Research Center, Crop Breeding and Cultivation Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China.
Plants (Basel). 2025 May 29;14(11):1657. doi: 10.3390/plants14111657.
Zinc (Zn) is an essential micronutrient required for plants to perform various metabolic functions, and plant responses to Zn deficiency have been extensively studied. However, excessive levels of Zn in soil can induce toxic effects in plants, posing a substantial challenge to global agricultural productivity. Consequently, elucidating the response mechanisms of crop plants to excessive Zn toxicity is currently of great significance. In this study, seedlings of maize inbred line B73 were exposed to excessive Zn treatment, and transcriptomic profiling of the roots was conducted at 0, 2, 6, 12, 24, and 48 h post-treatment. In addition to changes in the expression of genes encoding zinc-regulated, iron-regulated transporter-like protein (ZIP), metal tolerance protein (MTP), and yellow stripe-like (YSL) transporter family members involved in Zn transport, we observed that differentially expressed genes (DEGs) were significantly enriched in the phenylpropanoid-lignin metabolic pathway across all treatment stages, including the early (2 and 6 h), middle (12 and 24 h), and late (48 h) stages of Zn treatment. Among the 11 core structural enzyme-encoding genes involved in monolignols biosynthesis from phenylalanine in this pathway, the expression of eight of them was altered by Zn treatment. Additionally, genes encoding peroxidase (POD), which are responsible for the polymerization of monolignols into lignin, demonstrated extensive changes across all treatment stages, particularly at the late stage. The expression levels of these key enzyme genes were further validated using quantitative real-time PCR. Correspondingly, the activity of POD enzymes and the lignin content both significantly increased in Zn treated roots. These findings suggest that the phenylpropanoid-lignin metabolic pathway plays a crucial role in maize root responses to excessive Zn stress.
锌（Zn）是植物进行各种代谢功能所需的必需微量营养素，植物对锌缺乏的反应已得到广泛研究。然而，土壤中过量的锌会对植物产生毒性作用，给全球农业生产力带来重大挑战。因此，阐明作物对过量锌毒性的反应机制目前具有重要意义。在本研究中，将玉米自交系B73的幼苗进行过量锌处理，并在处理后0、2、6、12、24和48小时对根系进行转录组分析。除了参与锌转运的锌调节、铁调节转运蛋白样蛋白（ZIP）、金属耐受蛋白（MTP）和黄条纹样（YSL）转运蛋白家族成员编码基因的表达变化外，我们观察到在所有处理阶段，包括锌处理的早期（2和6小时）、中期（12和24小时）和后期（48小时），差异表达基因（DEG）在苯丙烷类-木质素代谢途径中显著富集。在该途径中由苯丙氨酸合成单木质醇的11个核心结构酶编码基因中，其中8个基因的表达因锌处理而改变。此外，负责将单木质醇聚合成木质素的过氧化物酶（POD）编码基因在所有处理阶段都有广泛变化，特别是在后期。使用定量实时PCR进一步验证了这些关键酶基因的表达水平。相应地，锌处理根系中POD酶的活性和木质素含量均显著增加。这些发现表明，苯丙烷类-木质素代谢途径在玉米根系对过量锌胁迫的反应中起关键作用。
