蓟马取食诱导对紫花苜蓿次生代谢物含量及防御酶活性的影响

Effects of thrips feeding on secondary metabolites and defense enzymes of alfalfa cultivars

摘要:

以抗蓟马苜蓿品种甘农 9 号(Medicago sativa cv. Gannong No. 9)、感蓟马苜蓿品种甘农 3 号 (Medicago sativa cv. Gannong No. 3)和高感蓟马苜蓿品种 WL363HQ(Medicago sativa cv. WL363HQ) 为试验材料，紫花苜蓿苗期接种不同头数(0、4、5、6 头/枝条)的蓟马成虫，取食 5 d 后比较不同抗性苜蓿品种叶片中次生代谢物质(黄酮、单宁、木质素)含量和防御酶(过氧化物酶(POD)、苯丙氨酸解氨酶 (PAL)、多酚氧化酶(PPO))活性的变化。结果表明：随着蓟马头数的增加，供试苜蓿品种的黄酮、单宁和木质素含量均显著高于 CK(P＜0. 05)。5、6 头/枝条处理时，甘农 9 号的单宁含量分别较甘农 3 号显著提高了 53. 49%，47. 70%；较 WL363HQ 分别显著增加了 71. 52%，58. 60%(P＜0. 05)。甘农 9 号的木质素含量在 5、6 头/枝条处理下均显著高于甘农 3 号和 WL363HQ，增幅分别为 5. 60%，3. 50% 和 6. 13%，3. 96%(P＜0. 05)。蓟马取食胁迫显著提高了供试苜蓿品种的 POD 和 PAL 活性，显著降低了 PPO 活性(P＜0. 05)。甘农 9 号的 POD 和 PAL 活性在 5 头/枝条处理下较甘农 3 号分别显著增加了 2. 60%，1. 09%；较 WL363HQ 分别显著提高了 1. 36%，3. 54%；6 头/枝条处理后甘农 9 号的 POD 和 PAL 活性均显著高于甘农 3 号(5. 19%，9. 36%)和 WL363HQ(2. 58%，11. 18%)(P＜0. 05)。

Abstract:

In this study， the effects of thrip feeding stress on secondary metabolites and defense enzymes in the three different thrip-tolerant alfalfa (Medicago sativa) cultivars， such as the thrip-resistant Gannong No. 9， thrip-sus- ceptible Gannong No. 3，and highly thrip - susceptible WL363HQ， were studied at the alfalfa seedling stage. The changes of flavonoids， tannins， lignin and the peroxidase (POD)， phenylalanine aminolyase (PAL)， polyphenol oxi- dase (PPO) were compared under the different thrip numbers (0 ，4，5 and 6 -thrip per branch) at 5 days of treat- ments. The results indicated that compared with CK， with the increase of thrip quantities， the content of flavonoid， tannin and lignin in Gannong 9， Gannong 3 and WL363HQ remarkably increased (P＜0. 05). In addition， under the 5 and 6-thrips per branch， compared with that in Gannong 3， the tannin contents of Gannong 9 were significantly en- hanced by 53. 49% and 47. 70%， respectively， and were significantly higher than that in WL363HQ (71. 52% and 58. 60%)(P＜0. 05). The lignin contents of Gannong 9 were significantly greater than Gannong 3 and WL363HQ under 5 and 6-thrips per branch， with an increase of 5. 60%，3. 50% and 6. 13%，3. 96%， respectively (P＜ 0. 05). Thrip infestation significantly improved the POD and PAL activities， and reduced the PPO activities of the tested alfalfa varieties (P＜0. 05). The activities of POD and PAL in Gannong 9 infested by 5-thrips per branch were significantly higher than Gannong 3(2. 60% and 1. 09%， respectively) and WL363HQ (1. 36% and 3. 54%， respectively). Under 6-thrips per branch the POD and PAL activities of Gannong 9 were 5. 19% and 9. 36% higher than Gannong 3， and were significantly increased by 2. 58% and 11. 18% compared with WL363HQ (P＜0. 05).