Mittapalli Omprakash, Shukle Richard H, Sardesai Nagesh, Giovanini Marcelo P, Williams Christie E
Department of Entomology, Purdue University, West Lafayette, IN 47907, USA.
J Insect Physiol. 2006 Nov-Dec;52(11-12):1143-52. doi: 10.1016/j.jinsphys.2006.08.007. Epub 2006 Sep 17.
We report on the transcriptional patterns of three antibacterial genes, a defensin (MdesDEF-1), a diptericin (MdesDIP-1) and a lysozyme (MdesLYS-1), during development in Hessian fly, Mayetiola destructor. Quantitative analysis by real-time PCR of mRNA levels in different tissues revealed a predominance of the transcripts for all three genes in the midgut, while analysis during development revealed greatest abundance in mRNA during the 3rd-instar. An evaluation of the midgut lumen revealed the presence of a diverse bacterial flora in larvae maintained on susceptible wheat. Further, the titer of bacteria in the midgut increased approximately 250-fold from the 1st-instar through the 2nd-instar. However, no detectable titer of bacteria was observed from the midgut lumen of larvae maintained on resistant plants. PCR amplicons produced using primers designed to conserved regions of the Pseudomonas 16S rRNA gene supported taxonomic identification for some of the bacteria comprising the midgut flora as belonging to the genus Pseudomonas. Analysis of mRNA for the Hessian fly antibacterial genes in larvae feeding on susceptible and resistant plants revealed an increase in the transcript level for MdesDEF-1 in 1st-instar larvae on susceptible plants, while the transcript levels for MdesDIP-1 and MdesLYS-1 were constant. Results suggest the transcriptional patterns of the Hessian fly antibacterial genes observed could be associated with the developing midgut bacterial flora present in larvae feeding on susceptible wheat as well as microbial challenge encountered at other stages in development.
我们报告了三种抗菌基因，即防御素（MdesDEF-1）、双翅肽（MdesDIP-1）和溶菌酶（MdesLYS-1）在小麦瘿蚊（Mayetiola destructor）发育过程中的转录模式。通过实时PCR对不同组织中mRNA水平进行定量分析，结果显示这三种基因的转录本在中肠中占主导地位，而发育过程中的分析表明，在三龄期mRNA丰度最高。对中肠腔的评估显示，以感病小麦为食的幼虫中存在多种细菌菌群。此外，中肠中的细菌滴度从一龄期到二龄期增加了约250倍。然而，在以抗病植物为食的幼虫中肠腔中未观察到可检测到的细菌滴度。使用针对假单胞菌16S rRNA基因保守区域设计的引物产生的PCR扩增产物支持将构成中肠菌群的一些细菌分类鉴定为假单胞菌属。对以感病和抗病植物为食的幼虫中小麦瘿蚊抗菌基因的mRNA分析显示，感病植物上一龄幼虫中MdesDEF-1的转录水平增加，而MdesDIP-1和MdesLYS-1的转录水平保持不变。结果表明，观察到的小麦瘿蚊抗菌基因的转录模式可能与以感病小麦为食的幼虫中发育中的中肠细菌菌群以及发育过程中其他阶段遇到的微生物挑战有关。
