Wang Nian, Lu Shi-En, Wang Jianlin, Chen Z Jeffrey, Gross Dennis C
Department of Plant Pathology and Microbiology and 2Department of Soil and Crop Sciences, Texas A&M University, College Station 77843, USA.
Mol Plant Microbe Interact. 2006 Mar;19(3):257-69. doi: 10.1094/MPMI-19-0257.
Specific plant signal molecules are known to induce syringomycin production and expression of syrB1, a syringomycin synthetase gene, in Pseudomonas syringae pv. syringae. This report demonstrates that syringopeptin production likewise is activated by plant signal molecules and that the GacS, SalA, and SyrF regulatory pathway mediates transmission of plant signal molecules to the syr-syp biosynthesis apparatus. Syringopeptin production by BR132 was increased two-fold by addition of arbutin (100 microM) and D-fructose (0.1%) to syringomycin minimal medium (SRM). Among 10 plant phenolic compounds tested, only the phenolic glucosides arbutin, salicin, and phenyl-beta-D-glucopyranoside induced substantially the beta-glucuronidase (GUS) activity of a sypA::uidA reporter from 242 U per 10(8) CFU without plant signal molecules up to 419 U per 10(8) CFU with plant signal molecules. Syringopeptin production was found to be controlled by the SalA/SyrF regulon because no toxin was detected from cultures of B301DSL7 (i.e., salA mutant) and B301DSL1 (i.e., syrF mutant), and the expression of sypA::uidA was decreased approximately 99 and 94% in salA (B301DSL30) and syrF (B301DNW31) mutant backgrounds, respectively. Subgenomic analysis of transcriptional expression with a 70-mer oligonucleotide microarray demonstrated that the syr-syp genes are induced 2.5- to 10.5-fold by addition of arbutin and D-fructose to SRM. This study establishes that plant signal molecules are transmitted through the GacS, SalA/SyrF pathway to activate the coordinated transcriptional expression of the syr-syp genes.
已知特定的植物信号分子可诱导丁香假单胞菌丁香致病变种产生丁香霉素并表达syrB1（一种丁香霉素合成酶基因）。本报告表明，丁香肽的产生同样受到植物信号分子的激活，并且GacS、SalA和SyrF调控途径介导植物信号分子向syr - syp生物合成装置的传递。通过向丁香霉素基本培养基（SRM）中添加熊果苷（100微摩尔）和D - 果糖（0.1%），BR132产生的丁香肽增加了两倍。在所测试的10种植物酚类化合物中，只有酚糖苷熊果苷、水杨苷和苯基 - β - D - 葡萄糖苷能显著诱导sypA::uidA报告基因的β - 葡萄糖醛酸酶（GUS）活性，在没有植物信号分子的情况下，每10⁸CFU的活性为242 U，而在有植物信号分子时，每10⁸CFU的活性高达419 U。发现丁香肽的产生受SalA/SyrF调节子控制，因为在B301DSL7（即salA突变体）和B301DSL1（即syrF突变体）的培养物中未检测到毒素，并且在salA（B301DSL30）和syrF（B301DNW31）突变体背景下，sypA::uidA的表达分别降低了约99%和94%。用70聚体寡核苷酸微阵列对转录表达进行亚基因组分析表明，向SRM中添加熊果苷和D - 果糖可使syr - syp基因的表达诱导2.5至10.5倍。本研究证实植物信号分子通过GacS、SalA/SyrF途径传递，以激活syr - syp基因的协同转录表达。
