Three gene promoters from the model legume species Medicago truncatula and Medicago sativa (alfalfa) pathogenesis-related (PR) proteins (MtPR5, MtPR10, and MsPR10) were isolated and investigated using in silico and in situ approaches. For the functional analysis of these promoters, plant transformation vectors linking promoter sequences with the β-glucuronidase (GUS) reporter gene were constructed and utilized to generate transgenic alfalfa. Histochemical GUS staining established that the PR5 and both PR10 promoters were functional in alfalfa and induce GUS expression primarily in the root tissue. When transgenic alfalfa leaves were inoculated with a diverse set of alfalfa pathogens, either Phoma medicaginis, Colletotrichum trifolii, or Pseudomonas syringae pv. syringae, the promoters were responsive to induction by both bacterial and fungal pathogens. Gene expression analysis also indicated that all three PR promoters were pathogen-induced and upregulate transgene expression. Additionally, several putative transcription regulator elements (REs) responsible for the observed pathogen-induced promoter activity were predicted in each of the promoter sequences. These characterized Medicago PR promoters may be a unique and valuable tool for pathogen-induced transgenic expression of antimicrobial proteins or other genes enhancing disease resistance in alfalfa.

从模型豆科植物苜蓿苜蓿和苜蓿（苜蓿）发病相关（PR）蛋白（MtPR5，MtPR10和MsPR10）的三个基因启动子被分离和使用计算机和原位方法进行了研究。为了对这些启动子进行功能分析，构建了将启动子序列与β-葡萄糖醛酸苷酶（GUS）报告基因连接的植物转化载体，并用于产生转基因苜蓿。组织化学GUS染色确定PR5和PR10启动子在苜蓿中均具有功能，并主要在根组织中诱导GUS表达。当转基因苜蓿叶与多样化的苜蓿病原体，无论是接种茎点霉苜蓿，炭疽病三叶草或丁香假单胞菌（Pseudomonas syringae pv。）丁香，启动子响应细菌和真菌病原体的诱导。基因表达分析还表明，所有三个PR启动子都是病原体诱导的并且上调了转基因表达。另外，在每个启动子序列中预测了负责观察到的病原体诱导的启动子活性的几种推定的转录调节元件（RE）。这些特征化的Medicago PR启动子可能是病原菌诱导的苜蓿中抗微生物蛋白或其他增强抗病性的基因转基因表达的独特而有价值的工具。