| Abstract: | Studies of the migration of second stage juveniles (JJ2) ofthe root-knot nematode Meloidogyne incognita in Arabidopsisroots were made at the cellular level using immunolabellingtechniques. A panel of antibodies that recognize epitopes presentin the plant extracellular matrix (JIMs) and the nematode cuticle(PC245) were used. The normal route for the juvenile (J2) hasbeen reconfirmed for both in vitro and in vivo conditions. Histologicalstudies show that, during migration towards the root meristem,juveniles (JJ2) sometimes break the physico-chemical barrierof the endodermis and establish close contact with the centralcylinder. Despite this, the juveniles continue their intercorticalmigration towards the root meristem. When the endodermis isbreached, hyperplasia and hypertrophy occur and a prematuregall is formed. Ultrastructural observations confirmed thatloosening of the middle lamella occurs during progress throughthe cortex. Differences in the patterns of labelling of healthyand infected roots were revealed when the antipolygalacturonicacid antibody, JIM5, was applied; epitopes recognized by thisantibody are mainly located on the triple junctions betweencells. Some of the antibodies used proved very useful in illustratingthe intercellular migration of JJ2 in the vascular cylinder,where they move in the vicinity of the protoxylem and futuremetaxylem cells. An envelope surrounding the nematodes, butlocated specifically on plant cell walls, was observed wheninfected rootsections were probed with PC245. This materialat this interface appears to be of nematode origin. Characterizationof the molecules involved is currently under investigation. Key words: Meloidogyne incognita, Arabidopsis thaliana, immunolabelling, JIM(s), migration |
