Department of Biochemistry & Molecular Biology, College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China.
BMC Plant Biol. 2020 Feb 3;20(1):54. doi: 10.1186/s12870-020-2265-1.
Lead (Pb) pollution is a widespread environmental problem that is harmful to living organisms. Tartary buckwheat (Fagopyrum tataricum), a member of the family Polygonaceae, exhibits short growth cycles and abundant biomass production, could be an ideal plant for phytoremediation due to its high Pb tolerance. Here, we aimed to explore the molecular basis underlying the responses of this plant to Pb stress.
In our study, ultrastructural localization assays revealed that Pb ions primarily accumulate in leaf vacuoles. RNA deep sequencing (RNA-Seq) of tartary buckwheat leaves was performed on two Pb-treated samples, named Pb1 (2000 mg/kg Pb (NO)) and Pb2 (10,000 mg/kg Pb (NO)), and a control (CK). A total of 88,977 assembled unigenes with 125,203,555 bases were obtained. In total, 2400 up-regulated and 3413 down-regulated differentially expressed genes (DEGs) were identified between CK and Pb1, and 2948 up-regulated DEGs and 3834 down-regulated DEGs were generated between CK and Pb2, respectively. Gene Ontology (GO) and pathway enrichment analyses showed that these DEGs were primarily associated with 'cell wall', 'binding', 'transport', and 'lipid and energy' metabolism. The results of quantitative real-time PCR (qRT-PCR) analyses of 15 randomly selected candidate DEGs and 6 regulated genes were consistent with the results of the transcriptome analysis. Heterologous expression assays in the yeast strain Δycf1 indicated that overexpressing CCCH-type zinc finger protein 14 (ZFP14) enhanced sensitivity to Pb, while 5 other genes, namely, metal transporter protein C2 (MTPC2), phytochelatin synthetase-like family protein (PCSL), vacuolar cation/proton exchanger 1a (VCE1a), natural resistance-associated macrophage protein 3 (Nramp3), and phytochelatin synthetase (PCS), enhanced the Pb tolerance of the mutant strain.
Combining our findings with those of previous studies, we generated a schematic model that shows the metabolic processes of tartary buckwheat under Pb stress. This study provides important data for further genomic analyses of the biological and molecular mechanisms of Pb tolerance and accumulation in tartary buckwheat.
铅（Pb）污染是一种广泛存在的环境问题，对生物机体有害。荞麦（Fagopyrum tataricum）是蓼科植物的一员，生长周期短，生物量丰富，对 Pb 具有较高的耐受性，因此可能是一种理想的植物修复材料。本研究旨在探讨该植物对 Pb 胁迫响应的分子基础。
在本研究中，超微结构定位分析表明 Pb 离子主要积累在叶片液泡中。对 2 个 Pb 处理组（Pb1：2000mg/kg Pb（NO3）2；Pb2：10000mg/kg Pb（NO3）2）和对照组（CK）的荞麦叶片进行 RNA 深度测序（RNA-Seq）。共获得 88977 条组装的 unigenes，总长度为 125203555bp。CK 和 Pb1 之间共鉴定到 2400 个上调和 3413 个下调的差异表达基因（DEGs），CK 和 Pb2 之间共鉴定到 2948 个上调和 3834 个下调的 DEGs。GO 功能注释和通路富集分析表明，这些 DEGs 主要与“细胞壁”、“结合”、“运输”和“脂质和能量”代谢有关。对随机选择的 15 个候选 DEGs 和 6 个调控基因进行定量实时 PCR（qRT-PCR）分析的结果与转录组分析结果一致。在酵母菌株Δycf1 中的异源表达实验表明，过表达 CCCH 型锌指蛋白 14（ZFP14）增强了对 Pb 的敏感性，而 5 个其他基因（金属转运蛋白 C2（MTPC2）、植物螯合肽合酶样家族蛋白（PCSL）、液泡阳离子/质子交换器 1a（VCE1a）、天然抗性相关巨噬细胞蛋白 3（Nramp3）和植物螯合肽合酶（PCS））增强了突变体菌株的 Pb 耐受性。
结合本研究和以往研究的结果，我们构建了一个示意图模型，展示了 Pb 胁迫下荞麦的代谢过程。本研究为进一步分析荞麦耐 Pb 和积累 Pb 的生物学和分子机制提供了重要数据。
