Abstract
Antimicrobial peptides are a potent group of defense active molecules that have been utilized in developing resistance against a multitude of plant pathogens. Floral defensins constitute a group of cysteine-rich peptides showing potent growth inhibition of pathogenic filamentous fungi especially Fusarium oxysporum in vitro. Full length genes coding for two Petunia floral defensins, PhDef1 and PhDef2 having unique C- terminal 31 and 27 amino acid long predicted prodomains, were overexpressed in transgenic banana plants using embryogenic cells as explants for Agrobacterium–mediated genetic transformation. High level constitutive expression of these defensins in elite banana cv. Rasthali led to significant resistance against infection of Fusarium oxysporum f. sp. cubense as shown by in vitro and ex vivo bioassay studies. Transgenic banana lines expressing either of the two defensins were clearly less chlorotic and had significantly less infestation and discoloration in the vital corm region of the plant as compared to untransformed controls. Transgenic banana plants expressing high level of full-length PhDef1 and PhDef2 were phenotypically normal and no stunting was observed. In conclusion, our results suggest that high-level constitutive expression of floral defensins having distinctive prodomains is an efficient strategy for development of fungal resistance in economically important fruit crops like banana.
Highlights
Banana (Musa spp.) is among the most important food crops in the world and constitutes the staple food for millions of people spread over different continents
Fusarium oxysporum, which is responsible for causing wilt disease in numerous crop plants, is a soil borne ubiquitous species complex of plant pathogens that includes several formae speciales, each having a high degree of host specificity
The present study describes the expression of two Petunia floral defensins in transgenic banana plants followed by detailed bioassays for resistance against Foc infection
Summary
Banana (Musa spp.) is among the most important food crops in the world and constitutes the staple food for millions of people spread over different continents. Biotic stress is imparted by the numerous diseases and pests, which when present in an area above a limited threshold, preclude banana cultivation altogether. Fusarium oxysporum, which is responsible for causing wilt disease in numerous crop plants, is a soil borne ubiquitous species complex of plant pathogens that includes several formae speciales, each having a high degree of host specificity. Foc invades and occludes the xylem vessels of the roots leading to severe wilting of the banana plant [5]. Leaves of infected banana plants become bright yellow and start collapsing around the pseudostem [7]. The disease was first reported in Australia in 1874 and it has spread to all banana cultivating regions of the globe except Papua New Guinea, the South Pacific Islands and some countries situated around the Mediterranean [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
