Overexpression of a soybean 4-coumaric acid: coenzyme A ligase (GmPI4L) enhances resistance to Phytophthora sojae in soybean

Phytophthora root and stem rot of soybean (Glycine max (L.) Merr.) caused by Phytophthora sojae is a destructive disease worldwide. The enzyme 4-coumarate: CoA ligase (4CL) has been extensively studied with regard to plant responses to pathogens. However, the molecular mechanism of the response of soybean 4CL to P. sojae remains unclear. In a previous study, a highly upregulated 4CL homologue was characterised through suppressive subtractive hybridisation library and cDNA microarrays, in the resistant soybean cultivar ‘Suinong 10’ after infection with P. sojae race 1. Here, we isolated the full-length EST, and designated as GmPI4L (P. sojae-inducible 4CL gene) in this study, which is a novel member of the soybean 4CL gene family. GmPI4L has 34–43% over all amino acid sequence identity with other plant 4CLs. Overexpression of GmPI4L enhances resistance to P. sojae in transgenic soybean plants. The GmPI4L is located in the cell membrane when transiently expressed in Arabidopsis protoplasts. Further analyses showed that the contents of daidzein, genistein, and the relative content of glyceollins are significantly increased in overexpression GmPI4L soybeans. Taken together, these results suggested that GmPI4L plays an important role in response to P. sojae infection, possibly by enhancing the content of glyceollins, daidzein, and genistein in soybean.

Molecular and genetic studies of the basis of virulence/avirulence in Meloidogyne chitwoodi

Within the EU project DREAM there is a programme of work investigating the molecular basis of virulence and avirulence in Meloidogyne chitwoodi and which involves partners from the Netherlands, France and Scotland. In Wageningen AFLPs are being used to examine genetic diversity between populations of M. chitwoodi. Partners in Wageningen and INRA are using M. javanica and M. incognita as model systems to isolate genes producing secreted proteins that could be implicated in the host pathogen interaction. They will search for homologous sequences in M. chitwoodi. At Rennes two-dimensional electrophoresis (2DE) studies are being conducted. The PCR based suppressive subtractive hybridisation (SSH), has been used at PRI and SCRI to compare avirulent and virulent nematodes and infected plant material (resistant and susceptible) at different times after infection.