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

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.

Overexpression of NPR1 in Brassica juncea Confers Broad Spectrum Resistance to Fungal Pathogens

“…In summary, overexpression of BjNPR1 into B. juncea imparts disease resistance to two economically important fungal pathogens, thereby supporting results from previous studies on NPR1 transgenic carrot ( Wally et al, 2009 ); cotton ( Parkhi et al, 2010 ), and peanut ( Sundaresha et al, 2016 ). Differences in the degree and development of disease symptoms caused by A. brassicae and E. cruciferarum between BjNPR1 and untransformed plants were clearly observed.…”

“…To evaluate the role of BjNPR1 in disease resistance, two lines (L2 and L5) were chosen for disease screening against Alternaria and powdery mildew infection. Recently, overexpression of NPR1 in peanut was reported to lead enhanced disease resistance against fungal pathogens ( Sundaresha et al, 2016 ). Consistent with these reports, the results of our study revealed that overexpression of BjNPR1 in B. juncea leads partial disease resistance against both necrotrophic ( A. brassicae ) and biotrophic ( E. cruciferarum ) fungal pathogen, as transgenic plants showed delayed symptoms, reduced mean lesion diameter, number of colonies and disease spreading to distal/non-infected parts of the plant ( Figures 7 , 8 ).…”

“…NPR1 overexpression in A. thaliana was reported to result an increase in the transcript levels of PR genes, hence proves that NPR1 -dependent PR gene mediated disease resistance ( Cao et al, 1997 ; Friedrich et al, 2001 ). Most recently, overexpression of NPR1 was also revealed to confer disease resistance against broad range of pathogens in different crops ( Dutt et al, 2015 ; Sundaresha et al, 2016 ). These results revealed that NPR1 is a potential candidate gene for developing disease resistant transgenic crops against multiple pathogens.…”

Can CRISPR Win the Battle against Huanglongbing?

“…Heat treatment reducing HLB symptoms may be due to the activation of PTI at higher temperature [69]. To enhance citrus HLB resistance, more genes can be transformed into plant based on different strategies [70]. A system from Arabidopsis, uORF-mediated translation was used to express AtNPR1 without fitness costs of rice [51], may benefit transgenic approach for citrus HLB resistance.…”

Characterization of NPR1 and NPR4 genes from mulberry (Morus multicaulis) and their roles in development and stress resistance

“…It was demonstrated that NPR1 serves as a coactivator of transcription, and mutants with defects in NPR1 fail to express several pathogenesis-related protein (PR) genes or develop SAR and are more prone to fungal and bacterial infections (Kinkema et al 2000, Ding et al 2018. In contrast, the overexpression of NPR1 in many species confers transgenic plants enhanced resistance to diverse pathogens (Chern et al 2001, Fitzgerald et al 2004, Makandar et al 2006, Sundaresha et al 2016, Ali et al 2017. Moreover, NPR1 is not only involved in the defense response but also in some other biological processes.…”