Author Details: Dr. S.K. Singh and D.N.Shukla, Department of Plant Pathology, RPCAU, PUSA
Corresponding Authors’ Email: email@example.comfirstname.lastname@example.org
Panama wilt in dwarf group of bananas incited by Fusarium oxysporum f.sp. cubense tropical race 4 was confined by Indonesia, Malaysia, Philippines, mainland China and Taiwan for more than three decades and now it has been expanded to Laos, Myanmar and Vietnam(3), even in Sindh province of Pakistan(1). Banana production in India account about 15.5 percent in area, its contribution is 25.58 per cent at global level that makes it leading banana producing country at world. In all the banana producing states of India, Bihar stood on sixth position in banana production. Panama wilt (Fusarium oxysporum f. sp. cubense race I & II) was a major problem of tall bananas i.e. Malbhog (AAB), Alpan (AAB), Champa (AAB), Chini Champa (AB), Kanthali (AAB), Kothia (ABB) in Zone –I comprising of (Samastipur Muzaffarpur, Vaishali, Hazipur districts) in Bihar. Koshi belt of Bihar was not known to be infected by Panama wilt before 2014-15(3). However, during the last 3-4 years, Panama wilt disease was unexpectedly observed in some banana plantations of Koshi belt (Purnea, Katihar, Navgachhiya, Madhepura and Kishanganj) in cultivar Robusta and Grand naine creating havoc among banana growers of Koshi belt. The affected samples were collected and brought to fruit Pathology laboratory at RPCAU, Pusa, pathogen isolated and detailed study conducted. Initially morphological examination of the isolates showed the presence of macroconidia, microconidia and chlamydospores as in case of Fusarium oxysporum f.sp. cubense. The tissue culture banana plants cv. Grand naine having 4 to 6 leaves was planted in pots contain sterilized mixture of silt and FYM. For confirmation of pathogenicity, the test plants were inoculated with Fusarium oxysporum f.sp. cubense by mixing the pure culture of pathogen to the medium in pots. Watering done by using sterilized distilled water on alternate days and plants were kept in green house at temperature of 25-300C. The symptoms were noticed within 14-16 days of inoculation. The fungus was again obtained on PDA medium as described from artificially inoculated plants (Fig.1.1).
Figure 1.1-External, Internal symptoms, and pure culture of Fusarium oxysporum f.sp. cubense
Pathogenicity test was also confirmed and characterisation as described by Altschul(4) in which the genomic DNA was isolated in pure form and ITS region of rDNA was successfully amplified using fungal universal ITS4 and ITS5 followed by sequencing PCR was set up with ABI-Big Dye℗ terminator v3.1 cycle sequencing kit and raw sequence obtained from ABI 3100 automated DNA sequencer was manually edited for inconsistency and the sequence data was aligned with publicly available sequence and analyse to reach identity. The fungal strain showed 100% sequence similarity with Tropical Race 4, sequence analyses with NCBI accession number LT571434.1, Fusarium oxysporum f.sp. cubense race-4 strain B2 resulted in alignment statistics: Query length-494, Score-892bits(988), Exept-0.0,Identities-494/494(100%), Gaps 0/494(0%), Strand Plus/Minus.
Thus, first time we confirm the presence of TR4 in Bihar states of India. Work on management of Panama wilt of banana incited by Fusarium oxysporum f.sp. cubense tropical race 4 is in progress.
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- Altschul, S.F. et al. “Basic local alignment search tool.” J. Mol.Biol.215:403-410, 1990.