茉莉酸甲酯和磷酸氢二钾诱导柱花草对炭疽病的抗性

探究茉莉酸甲酯（Methyl Jasmonate,MeJA）和磷酸氢二钾（K2HPO4）诱导柱花草对炭疽病的抵抗作用。结果表明,二者浓度分别为0.001~0.1 mgmL-1和10~50 mmolL-1时,病情指数均显著降低（P0.05），最佳诱导浓度分别是0.001 mgmL-1和30 mmolL-1，诱导效果分别是64.84 %和54.40 %。0.001 mgmL-1 MeJA处理组的过氧化物酶（POD）及多酚氧化酶（PPO）活性在48 h达到最大值，显著高于对照组。30 mmolL-1 K2HPO4处理组的POD与PPO活性分别在48和24 h达到最大值，显著高于对照组。两种诱抗剂处理的POD和PPO活性在接种早期增加了柱花草对炭疽菌的侵染的抵御能力，进而提高植株的抗病性。30 mmolL-1 K2HPO4处理组的过氧化氢酶（CAT）活性在48~72 h内上升，显著高于对照组,而0.001 mgmL-1 MeJA处理组的CAT活性除72 h显著低于对照组，其他时间点与对照组相差不大。说明在诱导柱花草抗病性方面，两种诱导抗性剂处理的诱抗效果与POD、PPO和CAT的酶活性的诱导的时间及程度有关。

The resistance of Stylosanthes guianesis to Colletotrichum gloeosporioides induced by methyl jasmonate and K2HPO4

The effects of methyl jasmonate (MeJA) and K2HPO4 on induced resistance of Stylosanthes guianesis cv CIAT184 to Colletotrichum gloeosporioides were studied. The results indicated that the disease indexes of S. guianesis decreased significantly (P0.05) by treatments of MeJA with concentration ranged from 0.001 to 0.1 mgmL-1 and K2HPO4 with concentration ranged from 10~50 mmolL-1. The optimal concentration of MeJA and K2HPO4 treatment was 0.001 mgmL-1 and 30 mmolL-1, respectively, which had induced effects of 64.84% and 54.40%, respective. The activities of POD and PPO in plants treated with 0.001 mgmL-1 MeJA increased and reached maximum at 48 hour after inoculation, which were significantly (P0.05) higher than those in control plant without MeJA. The activities of POD and PPO in plants treated with 30 mmolL-1 K2HPO4 increased and reached maximum at 48 hour and 24 hour after inoculation, respectively, which were significantly (P0.05) higher than those in control plants without K2HPO4. These results suggested that MeJA and K2HPO4 increased the activities of antioxidant enzymes like POD and PPO in the early stage after inoculation to improve the resistance of S. guianesis to anthracnose after inoculation. The activities of CAT in plants treated with 30 mmolL-1 K2HPO4 increased from 48 hour to 72 hour after inoculation, which were significantly (P0.05) higher than those in control plants without K2HPO4. However, the activities of CAT in plants treated with 0.001 mgmL-1 MeJA were similar with those in control plants without MeJA excepted with the former one was significantly (P0.05) lower than later one at 72 hour after inoculation. These results indicated that the induced effects of these two chemicals on the disease resistance of S. guianesis to C. gloeosporioides were related with the activities and induced time of POD, PPO and CAT.