National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Republic of Korea.
Microbiol Res. 2012 Jun 20;167(6):326-31. doi: 10.1016/j.micres.2011.11.002. Epub 2011 Dec 9.
Xanthomonas oryzae pv. oryzae causes bacterial blight in rice, and this bacterial blight has been widely found in the major rice-growing areas. We constructed a transposon mutagenesis library of X. oryzae pv. oryzae and identified a mutant strain (KXOM9) that is deficient for pigment production and virulence. Furthermore, the KXOM9 mutant was unable to grow in minimal medium lacking aromatic amino acids. Thermal asymmetric interlaced-PCR and sequence analysis of KXOM9 revealed that the transposon was inserted into the aroC gene, which encodes a chorismate synthase in various bacterial pathogens. In planta growth assays revealed that bacterial growth of the KXOM9 mutant in rice leaves was severely reduced. Genetic complementation of this mutant with a 7.9-kb fragment containing aroC restored virulence, pigmentation, and prototrophy. These results suggest that the aroC gene plays a crucial role in the growth, attenuation of virulence, and pigment production of X. oryzae pv. oryzae.
稻黄单胞菌引起水稻细菌性条斑病，这种细菌性条斑病广泛存在于主要的水稻种植区。我们构建了稻黄单胞菌 pv. 稻致病变种的转座子突变体文库，并鉴定出一个突变菌株（KXOM9），该突变菌株缺乏色素产生和毒力。此外，KXOM9 突变体无法在缺乏芳香族氨基酸的最小培养基中生长。热不对称交错 PCR 和 KXOM9 的序列分析表明，转座子插入到 aroC 基因中，该基因在各种细菌病原体中编码分支酸合酶。在植物体内生长试验表明，KXOM9 突变体在水稻叶片中的细菌生长受到严重抑制。用包含 aroC 的 7.9kb 片段对该突变体进行遗传互补恢复了毒力、色素形成和原养型。这些结果表明，aroC 基因在稻黄单胞菌 pv. 稻致病变种的生长、毒力衰减和色素产生中起着至关重要的作用。
