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A molecular construct to study the expression pattern of a wound-inducible promoter during insect attack

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  • Chemistry

Abstract

Glucuronidase Expression in Transgenic Tobacco Roots with a Parasponia Promoter on Infection with Meloidogyne javanica VOLUME 28 JOURNAL OF NEMATOLOGY DECEMBER 1996 NUMBER 4 Journal of Nematology 28(4):407-413. 1996. © The Society of Nematologists 1996. Glucuronidase Expression in Transgenic Tobacco Roots with a Parasponia Promoter on Infection with Meloidogyne javanica A. A. EHSANPOUR 2 AND M. G. K. JONES 3 Abstract: The expression of a g-us reporter gene linked to a Parasponia andersonii hemoglobin promoter has been studied in transgenic tobacco plants after infection by Meloidogyne javanica. Transgenic roots were harvested at different times after nematode inoculation, and stained his- tochemically for expression of the gus gene. During the early stages of infection (0-2 weeks) there was little expression in giant cells, in contrast to other cells of the root. In later stages of infection (3-6 weeks) there was strong gu.~ expression in giant cells, with virtually no expression in other cells of the root. The Parasponia hemoglobin promoter therefore appears to direct down-regulation of linked genes on induction of giant cells, but up-regulation in mature giant cells. This reflects different metabolic activities in the giant cells depending on their stage of development. The Parasponia hemoglobin promoter may respond to oxygen tension in giant cells. This suggests that oxygen tension may be limited in the metabolically active giant cells that are associated with egg-laying females. Key words: down-regulation, gene expression, glucuronidase, Meloidogyne javanica, nematode, Nicotiana tabacum, Parasponia andersonii, root-knot nematode, tobacco, up-regulation. The expression of genes in cells of host plant roots is affected by infection with nematodes. This is clearly evident, for ex- ample, in the formation of giant cells in susceptible host roots that are induced by root-knot nematodes, and from which the nematodes feed (12-14). Knowledge of gene

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