Enhancement of growth and Panama wilt resistance in banana by in vitro co-culturing of banana plantlets with PGPR and endophytes

Asia, more specifically Southeast Asia and India, is the center of diversity for banana (Musa spp.). Banana cultivation is not free from problems, constraints and challenges, especially pests and diseases which cause huge economic losses to the farming community. Among these, Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is one of the most important production constraints and is widespread in susceptible cultivars with 80-90% severity in many banana growing states in India. Apart from plant resistance, no sustainable solution has been found to control Fusarium wilt. Of late, tissue-culture bananas are increasingly being used by the Indian banana industry because they are the best source of disease and pest-free planting material and productivity on the farm can be greatly improved with their use. Nevertheless, tissue culture banana plantlets are found to be more susceptible to pests and diseases due to their pliable nature and lack of withstanding in the natural environment. These problems may be overcome by the reintroduction of microorganisms or their mixtures in order to protect them against diseases, improved establishment as well as overall performance. Plant growth and disease development were tested on the disease-susceptible cultivar ‘Red Banana’ (AAA) after Fusarium infection of tissue culture plantlets bacterized in vitro (by co-culturing with the bacterium) and non-bacterized plantlets. Results revealed that significant differences in both disease suppression and plant growth were obtained between in vitro bacterized and non-bacterized plantlets. Among the treatments, banana plantlets treated with mixture of bacterial strains viz., EPB 10+EPB 56+Pf1 was significantly effective in reducing Foc incidence under glass house conditions over control. In glass house experiments, expression of defence related enzymes was more in the plants treated with consortium of bacterial strains than the control plants. The morphological and physiological characters were also well pronounced in the consortium of bacterial strains viz., EPB 10+EPB 56+Pf1 treated plantlets indicating its plant growth promoting nature. The artificial inoculation method (in vitro co-culturing of plantlets with the bacterium) provided a foundational understanding of ecological enrichment to control banana wilt disease in future.