Cloning And Expression Of HOX Genes In Bursaphelenchus Xylophilus

Pine wilt disease(PWD) is a quarantine disease caused by pine wood nematode, Bursaphelenchus xylophilus, damaging several pine tree species in world wide with particular respect in China. Numerous studies on B. xylophilus have been done in many aspects like taxology, rapid identification, genetics and behaviour ecology, however, litte is known for reproduction and development at molecular biology level. HOX family is a group of conserved and developmental genes responsible for body plan along anterior-posterior axis and cell fate decision during embryogenesis and organogenesis in all animals. Study on HOX gene expression regulation of B. xylophilus is one of the most important issues of modern science, which will contribute the discovery of its developmental and evolutionary mechanisms. In the present study, we cloned the HOX genes, analyzed the protein structures of their functional domains, investigated the expression sites of different genes in different developmental periods and sexual individuals by in situ and transgenic technology, and proved the function of different genes. The main results are as follows:1) The HOX gene cluster of B. xylophilus has 5 members, including lin-39, mab-5, ceh-13, egl-5 and php-3.2) Full-length DNA of B. xylophilus HOX genes were sequenced and registered in the gene bank accession. Their gene bank accession numbers are KM891588, KM116504, KM116502, KM116503 and KM116505 for lin-39, mab-5, ceh-13, egl-5and php-3 respectively. 3) HOX genes of B. xylophilus are clustered in the genome with the order that lin-39, mab-5, ceh-13, egl-5 and php-3 along the anteroposterior(A-P) body axis, which is co-linear with their ralative genomic position. 4) The structures of protein were predicted with SWISS-MODEL modeling software based on the amino acid sequenceof HOX gene functional domain. The results showed that lin-39, mab-5 and ceh-13 shared the same structure of protein, but this structure was diferent from that of egl-5 and php-3 gene.5) All HOX genes are expressed in genital area for both male and female, but php-3 is expressed in whole tail, which means php-3 is expressed in much larger scale than others in the adult development period. For the J4 and J2 nematode, all 5 HOX genes are not expressed. For J3 nematode, however, lin-39, mab-5, ceh-13 and egl-5are expressed in most area of body, but php-3 is only expressed in tail. During the eggdevelopmental period, the expression areas of different genes are not regular with great differce with each other.