Engineering resistance to Fusarium wilt

Abstract

Banana is an important crop grown worldwide. Panama disease caused by Fusarium oxysporum f.sp. cubense (Foc) is more devastating and causes 100 % yield loss in many cultivars of banana. Foc is known to exist as four important races (races 1, 2, 3 and 4) of which races 1 and 4 are of serious concern as it attacks the commercially acceptable banana cultivars across the globe. Foc has been continuously evolving and hence pathogen variability has posed a great challenge to banana industry. Genetic modification of banana has been a widely accepted tool due to the limited success of conventional breeding. Current review highlights on the application of genetic engineering for imparting resistance against Fusarium wilt which has been the main goal of researchers worldwide. We discuss the various strategies that have been employed involving PR-related genes (defensin gene), antimicrobial genes (Ace-AMP1 gene), antiapoptosis gene and RNAi-mediated approach - host-induced gene silencing (HIGS) that confers a certain level of tolerance towards pathogen infection. Further the cisgenic approach utilizing R genes and native cell-death genes from Musa spp. has also proven promising. However the field trials that help to assess the efficiency of genes in situ are lacking in many of the studies. The understanding of host-pathogen interaction in terms of defence and pathogen-related pathways and the study of pathogenicity mechanism help in identifying critical genes for targeting pathogen and to evolve resistant cultivars employing cisgenic and transgenic approaches.