Plant Defensin from Alfalfa Confers Resistance to Leaf Rust in Transgenic Wheat

Leaf rust caused by the fungus Puccinia triticina (Pt) is an economically important wheat disease causing significant yield losses. While resistant cultivars have been used to control it, genetic resistance is brief and is ineffective with the emergence of new virulent races. Development of new transgenic wheat expressing an antifungal defensin offers a promising approach to combat the disease.

The research team led by Jagdeep Kaur from the Donald Danforth Plant Science Center transformed two wheat genotypes using a chimeric gene encoding an antifungal plant defensin, MtDEF4.2, from alfalfa (Medicago truncatula). The transgenic lines developed from independent events were then evaluated.

Analysis revealed that homozygous transgenic wheat lines expressing MtDEF4.2 displayed resistance to the Pt race MCPSS compared to non-transgenic controls. Further analysis suggested the presence of both pre- and post-haustorial resistance to leaf rust in the transgenic lines. However, MtDEF4.2 did not affect the colonization of the beneficial mycorrhizal fungus Rhizophagus irregularis in the roots.

The results suggest that the plant defensin MtDEF4.2 can provide substantial resistance to leaf rust in transgenic wheat without affecting the plants symbiosis with the beneficial mycorrhizal fungus.

For more information on this study, read the full article in Transgenic Research.