摘要
酚氧化酶主要以无活性的酚氧化酶原(prophenoloxidase,PPO)形式存在,酚氧化酶活性在昆虫密度依赖的抗病性中具有重要作用。本研究克隆了草地螟Loxostege sticticalis酚氧化酶原基因LsPPO,通过RT-qPCR研究了草地螟不同发育阶段、组织,及不同密度幼虫感染球孢白僵菌前、后LsPPO转录水平的变化规律。结果表明,LsPPO cDNA全长2055 bp,编码685个氨基酸,其中包含有6个保守组氨酸组成的2个铜离子结合位点以及硫羟酸酯区域,与欧洲玉米螟Ostrinia nubilalis、亚洲玉米螟O.furnacalis的PPO氨基酸序列相似性较高。在草地螟不同发育阶段,LsPPO转录水平以预蛹期最高,其次为3、4龄幼虫,其他发育阶段较低,草地螟不同组织LsPPO转录水平以血淋巴中最高,显著高于表皮、脂肪体和中肠。不同饲养密度的草地螟幼虫LsPPO转录水平存在显著差异。感染球孢白僵菌前,以幼虫密度10头/瓶的LsPPO转录水平最低,明显低于1头/瓶和30头/瓶,但感病后以幼虫密度10头/瓶的LsPPO转录水平最高,显著高于其他2个密度。3个密度幼虫感病后的LsPPO转录水平明显高于感病前。综上所述,幼虫密度胁迫影响草地螟酚氧化酶原基因的转录水平。
Phenoloxidase mainly exists in the inactive form as prophenoloxidase(PPO),and research has demonstrated that phenoloxidase activity plays an important role in insect density-dependent disease resistance.In this study,the Loxostege sticticalis prophenoloxidase gene(LsPPO)was cloned,and its transcription levels were analyzed using RT-qPCR in different developmental stages and tissues,as well as in larvae reared at different densities before and after Beauveria bassiana infection.The results showed that the full-length of LsPPO cDNA was 2055 bp,encoding 685 amino acids,including two copper-binding sites composed of six conserved histidine residues and thiolester site.The amino acid sequence of LsPPO exhibited high similarity to PPO sequences from Ostrinia nubilalis and O.furnacalis.The relative transcription level of LsPPO was highest in the prepupal,followed by the 3rd and 4th instar larvae,with lower expression in other developmental stages.Among different tissues,LsPPO expression was highest in the haemolymph,significantly higher than that in the cuticle,fat body and midgut.Significant differences in LsPPO transcription levels were observed among larvae reared at different densities.Before Beauveria bassiana infection,the lowest LsPPO relative transcription level was detected in larvae reared at density of 10 individuals per jar,which was significantly lower than in larvae reared at densities of 1 and 30 individuals per jar.However,after infection,LsPPO expression was the highest in larvae reared at 10 individuals per jar,significantly higher than that of the other two density groups.At the same time,the relative transcription levels of LsPPO in all three densities were significantly higher after infection than before.These findings indicate that larval density stress affects the expression of the LsPPO gene in L.sticticalis.
作者
蒋苏皖
王成
程云霞
张蕾
江幸福
孔海龙
JIANG Suwan;WANG Cheng;CHENG Yunxia;ZHANG Lei;JIANG Xingfu;KONG Hailong(College of Plant Protection,Yangzhou University,Yangzhou 225009,China;State Key Laboratory for Biology of Plant Diseases and Insect Pests,Institute of Plant Protection,Chinese Academy of Agricultural Sciences,Beijing 100193,China;Gaoyou Agricultural Technology Comprehensive Service Center of Yangzhou City in Jiangsu Province,Yangzhou 225600,China)
出处
《植物保护》
北大核心
2025年第3期16-22,61,共8页
Plant Protection
基金
国家重点研发计划(2022YFD1400600)
国家自然科学基金(32172397)。
关键词
草地螟
酚氧化酶原基因
球孢白僵菌
幼虫密度
Loxostege sticticalis
prophenoloxidase gene
Beauveria bassiana
larval density
