Transgenic banana expressing Pflp gene confers enhanced resistance to Xanthomonas wilt disease

Abstract

Banana Xanthomonas wilt (BXW), caused by Xanthomonas campestris pv. musacearum, is one of the most important diseases of banana (Musa sp.) and currently considered as the biggest threat to banana production in Great Lakes region of East and Central Africa. The pathogen is highly contagious and its spread has endangered the livelihood of millions of farmers who rely on banana for food and income. The development of disease resistant banana cultivars remains a high priority since farmers are reluctant to employ labor-intensive disease control measures and there is no host plant resistance among banana cultivars. In this study, we demonstrate that BXW can be efficiently controlled using transgenic technology. Transgenic bananas expressing the plant ferredoxin-like protein (Pflp) gene under the regulation of the constitutive CaMV35S promoter were generated using embryogenic cell suspensions of banana. These transgenic lines were characterized by molecular analysis. After challenge with X. campestris pv. musacearum transgenic lines showed high resistance. About 67% of transgenic lines evaluated were completely resistant to BXW. These transgenic lines did not show any disease symptoms after artificial inoculation of in vitro plants under laboratory conditions as well as potted plants in the screen-house, whereas non-transgenic control plants showed severe symptoms resulting in complete wilting. This study confirms that expression of the Pflp gene in banana results in enhanced resistance to BXW. This transgenic technology can provide a timely solution to the BXW pandemic.

Unlocking the potential of tropical root crop biotechnology in east Africa by establishing a genetic transformation platform for local farmer-preferred cassava cultivars

“…The introduction of PRR genes, such as the Xa21 from rice or EFR ( Elongation Factor Receptor ) in cassava, could provide a broad and durable resistance to CBB, as has been demonstrated for other plants (Lacombe et al, 2010; Mendes et al, 2010). Genetically engineered resistance against bacteria has also been achieved in banana by using genes regulating programmed cell death such as hypersensitive response-assisting protein ( Hrap ) and plant ferredoxin-like protein ( Pflp ) from sweet pepper ( Capsicum annuum ) (Tripathi et al, 2010; Namukwaya et al, 2012). Such an approach could also be used to enhance resistance of cassava against bacterial blight in the near future.…”

“…The scientific approach followed in this report will serve as model to implement genetic transformation of other cassava cultivars that are agronomically important in Africa. In sub-Saharan Africa, capacities for the production of transgenic crop plants have only recently been developed and remain limited to few crops like banana and maize (Tripathi et al, 2010, 2012; Namukwaya et al, 2012; Ombori et al, 2013). We consider that the present report represents an important step toward building a capacity for transgenic technologies in sub-Saharan Africa.…”

Modifying Bananas: From Transgenics to Organics?

“…The accessible gene pool available for GM is significantly broader than that available to conventional banana breeders and, as a result, genes for resistance to BBTV and BXW have already been identified [44][45][46][47]. Further, genes from M. balbisiana are available for use in genetic modification, as there is no possibility of transferring BSV genes [48].…”

“…The transgenic lines were screened in the glasshouse, before progressing to the field. Lines with either transgene were identified with an apparently complete resistance to BXW [45][46][47]. The program has progressed further as the two genes, either alone or in combination, have been transformed into Nakitembe, the East African Highland banana clone used in the PVA project.…”

Prospects for the utilization of genetically modified crops in Africa

“…They originated from the sweet pepper, Capsicum annuum L., and encode a plant ferrodoxin-like protein (PFLP) and a hypersensitive response assisting protein (HRAP). The former mediates electron transfer and the latter prevents the spread of pathogens by causing the rapid death of cells in the local area surrounding the infection(Tripathi et al 2010;Namukwaya et al 2012). Resistant banana lines (65) expressing either the Hrap or Pflp gene were subjected to confined field trials in Uganda for two successive crop cycles, artificially infected with X.…”