漆酶基因对叶菜细胞壁合成和镉积累品种间差异的调控作用

Heavy metal contamination in agricultural soils is a serious environmental problem all around the world. Studies about the cultivars with low cadmium (Cd) accumulation ability have thus been attracted a number of worldwide attention. Because the laccase genes play a very important role in cell wall synthesis, meanwhile, cell wall is able to absorb quite a number of Cd and effect the transcellular transport of Cd, the laccase genes may affect to genotype difference in Cd accumulation. Basing on our previous researches on the comparison between high- and low-Cd vegetable cultivars in transcriptome sequencing, we find that the laccase genes are significantly differentially expressed. In this study, we aim to clarify the laccase gene family attended mechanisms in the genotype difference of Cd accumulation in vegetables including Brassica parachinensis, Brassica campestris, and Ipomoea aquatica. qRT-PCR will be used to explore the Cd accumulation related laccase genes. The full-length of laccase gene will be obtained by RACE method, and the nucleotide differences of the laccase gene between high-Cd and low-Cd cultivars will also be obtained. Finally, Arabidopsis thaliana over expression and RNAi system will be constructed to verify the functions of the laccase genes. The results of this study will be valuable for further understanding the laccase genetic mechanisms associating to the genotype difference in Cd accumulation of the vegetables, and developing molecular breeding method for low-Cd cultivar of vegetables which is important in the insurance of food safety.

土壤重金属污染已成为世界性重大环境问题，镉低积累作物品种的研究在国内外备受关注。漆酶在细胞壁合成方面起重要作用，而细胞壁与镉的吸附和跨细胞转运有关，因而可能与作物镉积累品种差异有关。课题组前期研究发现蔬菜漆酶基因在镉胁迫下存在显著的品种间差异表达。本研究以菜心、小白菜和蕹菜镉高低积累品种为研究对象，利用qRT-PCR技术进一步分析漆酶家族基因的表达情况，筛选和鉴定与蔬菜镉积累能力品种间差异相关的漆酶基因。利用RACE技术克隆相关漆酶基因的cDNA全长，并比较其在高低品种间的序列差异。最后利用基因过表达和基因沉默技术技术验证上述漆酶基因及其碱基差异的功能，明确其对根细胞壁合成以及镉积累能力的影响。本研究对于进一步了解作物镉积累分子机理，发展镉低积累品种的分子辅助育种技术，保障食品安全有重要意义。

土壤重金属污染已成为世界性重大环境问题，镉低积累作物品种的研究在国内外备受关注。漆酶在细胞壁合成方面起重要作用，而细胞壁与镉的吸附和跨细胞转运有关，因而可能与作物镉积累品种差异有关。课题组前期研究发现蔬菜漆酶基因在镉胁迫下存在显著的品种间差异表达。本研究以菜心、小白菜和蕹菜镉高低积累品种为研究对象，利用qRT-PCR技术进一步分析漆酶家族基因的表达情况，筛选和鉴定与蔬菜镉积累能力品种间差异相关的漆酶基因。利用RACE技术克隆相关漆酶基因的cDNA全长，并比较其在高低品种间的序列差异。最后利用基因过表达和基因沉默技术验证上述漆酶基因及其碱基差异的功能，明确其对根细胞壁合成以及镉积累能力的影响。主要研究结果包括：1）明确了漆酶基因在典型叶菜镉高积累品种与镉低积累品种存在显著的品种间表达差异，预示着漆酶基因所介导的木质素合成过程对叶菜镉积累水平发挥关键作用。2）发现了典型叶菜镉高积累品种与镉低积累品种木质素组成和结构存在显著差异，并且这个过程受漆酶基因的影响。而不同的木质素结构由于镉结合能力的差异将会进一步影响植物的镉积累水平。3）明确了miRNA397在调控漆酶基因表达，影响植物镉积累水平和镉耐受性的重要角色，为进一步完善叶菜漆酶基因在镉积累过程的重要调控机制。本研究对于进一步了解作物镉积累分子机理，发展镉低积累品种的分子辅助育种技术，保障食品安全有重要意义。