Co-overexpression of Brassica juncea NPR1 (BjNPR1) and Trigonella foenum-graecum defensin (Tfgd) in transgenic peanut provides comprehensive but varied protection against Aspergillus flavus and Cercospora arachidicola.

ABSTRACT

KEY MESSAGE Coexpression of two antifungal genes ( NPR1 and defensin ) in transgenic peanut results in the development of resistance to two major fungal pathogens, Aspergillus flavus and Cercospora arachidicola. Fungal diseases have been one of the principal causes of crop losses with no exception to peanut (Arachis hypogeae L.), a major oilseed crop in Asia and Africa. To address this problem, breeding for fungal disease resistance has been successful to some extent against specific pathogens. However, combating more than one fungal pathogen via breeding is a major limitation in peanut. In the present study, we demonstrated the potential use of co-overexpression of two genes, NPR1 and defensin isolated from Brassica juncea and Trigonella foenum-graecum respectively; that offered resistance towards Aspergillus flavus in peanut. The transgenic plants not only resisted the mycelial growth but also did not accumulate aflatoxin in the seeds. Resistance was also demonstrated against another pathogen, Cercospora arachidicola at varied levels; the transgenic plants showed both reduction in the number of spots and delay in the onset of disease. PCR, Southern and Western blot analysis confirmed stable integration and expression of the transgenes in the transgenic plants. The combinatorial use of the two pathogen resistance genes presents a novel approach to mitigate two important fungal pathogens of peanut.