The effects of lipopolysaccharides (LPS) from Azospirillum brasilense Sp245, a plant growth-promoting rhizobacteria, and Pseudomonas aeruginosa PAO1, a pathogenic bacterium, on plant growth and peroxidase (POD) activity were assessed on wheat seedlings. A. brasilense LPS (100 µg/mL) increased total length, and total fresh weight in wheat seedlings 4 days after treatment. P. aeruginosa LPS did not show effect on plant growth. A. brasilense LPS increased root hairs length similar to whole cells, while P. aeruginosa LPS increased root hairs density and slightly root hairs length. Both LPS increased POD activity and hydrogen peroxide (H2O2) content in root; however, the LPS from the pathogenic bacterium generated higher increments. The peroxidase inhibitor salicylhydroxamic acid (SHAM) inhibited plant growth, which was not recovered by the addition of LPS neither A. brasilense nor P. aeruginosa. POD activity stimulated by LPS was calcium-dependent as confirmed by the addition of the calcium channel blocker LaCl3. The results suggest that plant cells sense differentially LPS from beneficial or pathogenic bacteria and that calcium is needed to respond to the presence of both LPS.

中文翻译：

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巴西固螺菌Sp245和铜绿假单胞菌PAO1脂多糖对小麦幼苗生长和过氧化物酶活性的影响比较

对来自 Azospirillum brasilense Sp245（一种促进植物生长的根际细菌）和 Pseudomonas aeruginosa PAO1（一种病原菌）的脂多糖 (LPS) 对小麦幼苗的植物生长和过氧化物酶 (POD) 活性的影响进行了评估。A. brasilense LPS (100 µg/mL) 在处理后 4 天增加了小麦幼苗的总长度和总鲜重。铜绿假单胞菌 LPS 对植物生长没有影响。A. brasilense LPS 增加根毛长度类似于全细胞，而 P. aeruginosa LPS 增加根毛密度和略微增加根毛长度。LPS 都增加了根的 POD 活性和过氧化氢 (H2O2) 含量；然而，来自病原菌的 LPS 产生了更高的增量。过氧化物酶抑制剂水杨基异羟肟酸 (SHAM) 抑制植物生长，通过添加 LPS 既没有 A. brasilense 也没有 P. aeruginosa 恢复。钙通道阻滞剂 LaCl3 的添加证实了 LPS 刺激的 POD 活性是钙依赖性的。结果表明，植物细胞对来自有益或致病细菌的 LPS 有不同的感知，并且需要钙来响应两种 LPS 的存在。