马铃薯糖苷生物碱对枸杞镰孢菌果腐病的诱导抗性及相关防御酶活性的影响

为探索马铃薯糖苷生物碱诱导采后枸杞鲜果抗病性的效应,采用菌丝生长速率法测定了离体条件下马铃薯糖苷生物碱对枸杞鲜果采后主要致腐病原菌镰孢菌Fusarium sp.的抑菌活性;采用浸泡处理法测定了马铃薯糖苷生物碱对采后枸杞鲜果发病病情指数及对果实多酚氧化酶(PPO)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)和超氧化物歧化酶(SOD)等相关防御酶活性的影响。结果表明:不同浓度马铃薯糖苷生物碱对镰孢菌均具有一定的抑制作用,EC50为0.11 g/mL;0.05～0.25 g/mL(提取原料)的马铃薯糖苷生物碱能显著降低采后枸杞鲜果病情指数,较对照降低了10.18%～38.51%;以0.15 g/mL(提取原料)的马铃薯糖苷生物碱处理后对枸杞鲜果抗果腐病的诱导效果最好,达45.81%;马铃薯糖苷生物碱处理枸杞鲜果后,果实中4种防御酶PPO、POD、PAL、SOD的活性均较对照有不同程度提高,分别于处理后第4、5、2、2天与对照差异达到最大,较对照提高了30.76%、21.34%、31.35%和21.91%。表明马铃薯糖苷生物碱能够诱导枸杞鲜果对采后病害的抗性效应,且采后抗病性可能与枸杞相关防御酶活性的增加有关。

Effect of potato glycoalkaloids on induced resistance of Fusarium fruit rot on Lycium barbarum and activities of related defense enzymes

In order to explore the effect of potato glycoalkaloids (TGA) on the disease resistance of postharvest fruit of Lycium barbarum L., the inhibitory activity of TGA to Fusarium sp., a major pathogen causing postharvest decay of fresh fruits, was determined in vitro by measuring growth rate of mycelia. The postharvest disease index and activities of related defense enzymes such as polyphenol oxidase (PPO), peroxidase (POD), phenylalnaine ammonialyase (PAL) and superoxide dismutase (SOD) of fresh fruits were also analyzed by solution supplemented with TGA. The results showed that different concentrations of TGA could inhibit the growth of the pathogen, the EC₅₀ value was 0.11 g/mL. 0.05-0.25 g/mL TGA (extraction of raw materials) could significantly reduce the postharvest disease index of fresh fruit of L. barbarum, which was reduced by 10.18% to 38.51%, compared with the control. The TGA (extraction of raw materials) treated with 0.15 g/mL had the best induction effect on the resistance of fresh fruit to fruit rot, reaching 45.81%. The activities of four kinds of defense enzymes such as PPO, POD, PAL and SOD in fruit were increased in different degrees compared with the control after treated with TGA. The difference of day 4, day 5, day 2 and day 2 reached the maximum after treatment, which were higher than that of control by 30.76%, 21.34%, 31.35% and 21.91%, respectively. The results indicated that TGA could induce the resistance of fresh fruit to postharvest diseases and postharvest disease resistance might be related to increased activity of related defense enzymes.