Pathogenesis And Function Study Of Parasitism Gene In The Esophageal Gland Of Meloidogyne Javanica

The root knot nematode,Meloidogyne javanica,is an obligate parasite that causes significant damage to a broad range of host plants.These obligate biotrophic pathogens establish an intimate relationship with their host plants,inducing the redifferentiation of root cells into specialized feeding cells.The successful establishment of feeding cells is essential for nematode development.Feeding cells enlarged and are converted into multinucleate giant cells through synchronous nuclear divisions without cytoplasm division.Fully differentiated giant cells may contain more than a hundred polyploid nuclei.Through the giant cells,root-knot nematode draws a lot of nutrients and water.Giant cell formation is the key to understand the principle of parasitic relationship between root-knot nematode and plants.The development of M.javanica was studied by paraffin sections in this thesis. Under suitable conditions,J2 began to penetrate root tip after infected 13h,and induced dramatic changes in selected root vascular cells to form giant cells after infected 2 days.L2 started to settle down in the roots after infected 4 days.Giant cell is fully formed after infected 8 days.L3 is formed after infected 13 days,and L4 formed after infected 17 days.Adult females began to produce eggs after infected 21 days,and spawning reached to a peak after infected 25 days.Spawning was accomplished after infected 32 days,and life cycle of M.javanica is completed.Pathogenic mechanism of M.javanica in tomato roots was studied by immunohistochemistry.The primary antibody was obtained from the kunming mouse immunized by the total protein of adult,and the various developmental stages of root-knot nematode was analyzed by immunohistochemistry.Compared to the results of protein components from different developmental stages of the root-knot nematode, suggest that the root-knot nematode secreted some molecules into the root tissue and induced the reprogramming of root cells into giant cells.The expressions of esophageal gland genes during the root knot nematode development were detected using western blot and immunolocalization.The total RNA was isolated from adult and larvae respectively,five esophageal gland genes and one hsp gene were amplified by RT-PCR,and expressed in E.coli,then immunized mouse to obtain antibody using the recombinant proteins.The expression of these genes in eggs,larval stage and adult of M.javanica were examined by western blot and immunostaining.The results show that msp-3,msp-21 andmsp-28 expressed only at the adult stage of M.javanica,msp-26 and hsp-90 expressed at eggs,larvae and adult stage;and msp-36 expressed only at second larvae stage.Additionally,according to the analysis of Nucleotide BLAST,msp-36 is a new gene which has never been reported before.