Why Mildew Resistant But Infertile Arabidopsis Plants

Two proteins, Feronia and Nortia were found to be involved in plant fertilization and susceptibility to powdery mildew infection in Arabidopsis thaliana, by scientists from Max Planck Institute for Plant Breeding Research in Cologne and the University of Zurich. The paper published in Science reports about the protein Feronia which signals the pollen tube that it has reached the embryo sac and has to dislodge the male gametes. The protein is also expressed in the leaves that allows access of the powdery mildew to the plant. Defective Feronia gene however could stop powdery mildew infection but will not lead to successful fertilization as the pollen tube will continuously penetrate the embryo sac and will not dislodge the male gametes.

The Nortia protein on the other hand, combined with Feronia, brings about the fusion of the gametes in the ovary. In Arabidopsis, Nortia has a homologue found in the leaves called MLO which together with Feronia enables mildew to penetrate the plant.

"This dual function indicates why evolution has not yet succeeded in blocking this point of access to mildew. It would clearly be very difficult to decouple these two functions. Therefore, the alternatives are: resistant and infertile, or vulnerable and fertile," says Ralph Panstruga from the Max Planck Institute for Plant Breeding Research. These findings will enable researchers to study in detail the genes coding for the proteins so as to develop mildew-resistant plants that are also fertile.

View http://www.mpg.de/bilderBerichteDokumente/dokumentation/pressemitteilungen/2010/pressemitteilung20101123/ for additional information.