THE PLANT CELL, Vol 5, Issue 12 1697-1710, Copyright © 1993 by American Society of Plant Biologists
Induction Patterns of an Extensin Gene in Tobacco upon Nematode Infection
A. Niebel, J. de Almeida Engler, C. Tire, G. Engler, M. Van Montagu and G. Gheysen
Laboratorium voor Genetica, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium
When sedentary endoparasitic nematodes infect plants, they induce complex
feeding sites within the root tissues of their host. To characterize cell
wall changes induced within these structures at a molecular level, we
studied the expression of an extensin gene (coding for a major structural
cell wall protein) in nematode-infected tobacco roots. Extensin gene
expression was observed to be induced very early upon infection. This
induction was weak, transient, and probably due to wounding during
penetration and migration of the tobacco cyst nematode Globodera tabacum
ssp solanacea-rum. In contrast, high extensin gene expression was observed
during the whole second larval stage (an ~2-week-long phase of
establishment of the feeding site) of the root knot nematode Meloidogyne
javanica. During later stages of this interaction, expression gradually
decreased. Extensin gene expression was found in at least three different
tissues of the gall. We propose that distinct mechanisms lead to induced
expression in these different cell types. The significance of these results
for the understanding of plant-nematode interactions as well as the
function of structural cell wall proteins, such as extensin, is discussed.
