Using laser capture microdissection to study gene expression in early stages of giant cells induced by root‐knot nematodes

SUMMARY Root‐knot nematodes ( Meloidogyne spp.) are economically important plant parasites that induce specific feeding cells called giant cells in host roots. Study of molecular events involved in induction and differentiation of giant cells has been limited because it is difficult to obtain pure cytoplasm specifically from the highly specialized cells. In this work, laser capture microdissection (LCM) was used to collect cytoplasmic contents from paraffin‐embedded sections of 4 day post‐inoculation giant cells in tomato roots. Total RNA was isolated from the sections, and used in RT‐PCR to investigate expression of cell cycle genes in giant cells. Two D‐type cyclin genes, Le CycD3 ;2 and Le CycD3 ;3, were expressed at higher levels in giant cells compared with other cell‐cycle‐related cyclin genes, suggesting that the induction of the G1 phase of the cell cycle may be triggered in response to stimulation by the infecting nematode. LCM provides a powerful new tool to study the molecular basis of host–pathogen interactions at the cellular or subcellular level.