Molecular Detection of Fusarium oxysporum f. sp. Cubense Race TR4 Infecting Banana Groups in Indo-Gangetic Plains of India

Panama wilt or Fusarium wilt incited by Fusarium oxysporum f. sp. cubense (Foc) is a major threat for banana cultivation and impacting symbolic economic losses worldwide. Previously Foc race 1 and race 2 was detected in India which eventually spread monoculture of ‘Cavendish’ bananas resistant against these two races. Later on, another new race TR4 of Foc was detected to be incited in ‘Cavendish’ group of banana raised an alarming situation to the global banana industry. In the present study detailed survey was conducted in popular banana growing districts of West Bengal, India for visualizing the impact of disease incidence as well as collection of isolates from infected suckers and rhizomes of ‘Cavendish’ banana with an aim to develop a rapid detection technique for apprehending the presence of Foc TR4 race at early infection stages. Methods comprised of field survey followed by isolation of pathogen, test of pathogenicity and further molecular detection through Foc TR4 specific primers. Results revealed that the colonies formed on the potato dextrose agar (PDA) medium exhibited typical characteristic of Foc. Pathogenicity test conducted by considering healthy plantlet of ‘Grand Naine’ also detected characteristic symptom of Foc. Additionally, PCR assay using specific markers followed by sequencing of 28S-18S ribosomal RNA intergenic spacer spacer (IGS) confirmed the presence of this isolate in the infected samples. Phylogenetic evolution assays revealed a very close relationship of the Foc TR4 strains of India with Asia-Pacific isolates of Foc TR4. This study advocated the urgency of prevention of introduction of Foc TR4 into disease-free areas in the banana growing districts of India for maintaining sustainable banana production.