杨树BOR基因在硼富集和高硼耐性中的作用

干旱半干旱地区富硼土壤和涉硼企业的硼污染对动植物的生长发育具有严重的负面影响。国外学者和我们的前期研究表明杨树可将硼富集在叶片中，适用于对富硼土壤进行生物修复。过去的研究集中在硼富集特征和应用前景等方面，忽视了对杨树高硼耐性相关生理和分子机制的研究。本项目拟分析杨属不同树种（胡杨、银白杨和俄罗斯杨）的耐硼性状差异及其生理基础，并通过分析硼转运蛋白家族（BOR）在硼胁迫条件下不同组织中的表达模式，筛选并克隆BOR关键基因。通过转化酵母和拟南芥突变体，分析杨树BOR的硼外排分子功能及亚细胞定位；通过构建超量表达载体和RNA干涉表达载体，转化俄罗斯杨，研究BOR在硼转运、分配和富集过程中的功能；通过构建BORpro::GUS转化俄罗斯杨，研究BOR基因启动子的组织特异性及其对硼胁迫的应答模式。研究结果将揭示杨属不同树种间高硼耐性差异的生理和分子基础，为富硼土壤修复植物的发掘和改良提供理论依据。

Boron toxicity occur naturally in many arid and semi-arid regions across the world, and may be produced by human activities such as surface mining and fertilization. It has been considered as a serious problem limiting plant growth, crop production and species distribution. Poplars are tolerant to boron toxicity and can be employed in phytoremediation of boron contaminated soil. However, the boron tolerant mechanism of poplar is largely unknown. In the present project, the boron tolerance of Populus euphratica, P. alba and P. russkii will be compared. The physiological responses, the characteristics of boron distribution, and the expression patterns of boron transporter (BOR)-like genes will be analyzed. Some BOR-like genes which may play a role in boron enrichment will be cloned and characterized in yeast, Arabidopsis thaliana, and P. russkii by overexpression and RNA interference. The promoters of these BOR genes will be fused to β-glucuronidase reporter gene to detect the tissue specificity and boron response patterns. This study will advance our understanding about the molecular mechanisms of boron tolerance and enrichment, and also provide theoretical basis for the identification or improvement of plant species which could be used in phytoremediation of boron contaminated soil.