Nematode infection and reproduction in transgenic and mutant Arabidopsis and tobacco with an altered phenylpropanoid metabolism.

Transgenic and mutant Arabidopsis and tobacco plants with altered phenylpropanoid metabolism were infected with the plant parasitic root knot nematode Meloidogyne incognita to assess the effect of the transgene or mutation on nematode infection and reproduction. Modifications in the lignin biosynthetic pathway which alter lignin composition in roots affected reproduction. In Arabidopsis with increased levels of syringyl lignin, reproduction was lower than in wild-type plants, while in tobacco with reduced levels of syringyl lignin, life cycle progression was stimulated. Overexpression of a MYB transcription factor of phenylpropanoid metabolism in tobacco significantly stimulated reproduction of M. incognita, while overexpression of L-phenylalanine ammonia-lyase had no effect. Arabidopsis transparent testa mutants with deficiencies in flavonoid pathway enzymes did not affect reproduction of M. incognita in the present infection tests.