Title: Exemplifying endophytes of banana (Musa paradisiaca) for their potential role in growth stimulation and management of Fusarium oxysporum f. sp cubense causing panama wilt

Abstract

Banana (Musa paradisiaca) is one of the major staple food crop for millions of people in Central, East, West Africa, Latin America and Caribbean islands. In 2016, world production of bananas and Musa spp. was 148 million tonnes, led by India and China with a combined total (only for bananas) of 28 per cent of the global production. In India, banana ranks first in production and among fruit crops, area wise it ranks third after mango and citrus. The production of banana accounting for 30.4 million tonnes from an area of 0.86 million ha with an average productivity of 35.4 tonnes/ha (Horticultural Statistics at a Glance, 2018). Among the different fruit crops available commercially worldwide, banana is also considered as “Poor man” apple in tropical, sub tropical and the under privileged nations of Sub-Saharan Africa. At present India, contributes approximately 21 per cent of total global banana production thus emerged as one of the largest producer of banana globally (Thangavelu et al., 2019). However, during cultivation banana plantains are attacked by several biotic stresses such as diseases, insect pests and nematodes which hinder its production. Among the diseases that are affecting banana cultivation, Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc), is considered as one of the most important yield limiting diseases in the tropical and subtropical regions of the world (Ploetz, 2015). Historically the Fusarium wilt, also known as “Panama wilt” is the main culprit in destroying Gross Michel cultivar in Central America during 1950s (Dita et al., 2018). In the present study, potentiality of endophytic microorganisms such as Rigidiporus vinctus AAU EF, Trichoderma reesei UH EF and Sphingobacterium tabacisoli UH EB in the management of panama wilt and growth promotion of banana was assessed through, artificial inoculation. During the study, a total of 220 bacterial and 110 fungal endophytes were isolated from root, pseudostem and leaf samples of banana, and they were evaluated against Fusarium oxysporum f. sp cubense causing panama wilt. Out of total 330 bacterial and fungal endophytes, only five endophytes exhibited antagonism against Fusarium oxysporum f. sp cubense, out of which only three isolates, namely Trichoderma reesei UH EF, Rigidiporus vinctus AAU EF and Sphingobacterium tabacisoli UH EB, produced Indole acetic acid, siderophore and Hydrogen cyanide, except one bacterial strain Sphingobacterium tabacisoli UH EB does not produced Hydrogen cyanide. Furthermore, these three endophytes were identified through cultural and morphological characteristics as well as by the sequencing internal transcribed spacer (ITS) and 16S rRNA gene sequences analysis for bacteria respectively. The response of host plant to endophyte inoculation was assessed by measuring the change in four growth parameters; plant height, pseudo stem girth (diameter), number of roots and total number of leaves. The application of endophytes, irrespective of isolate and treatment type promoted the overall growth of the plant growth when compared with diseased plants with significant higher values recorded for all parameters assessed. The endophytes reported as growth promoters were found to have significant inhibition effect on Foc which can evidenced with lowest AUDPC values and epidemic rate at 99.09 units2 and 0.02 unit d-1 respectively.