First report of Berkeleyomyces basicola causing mango root rot and decline in India
Mango wilt has been a severe constraint in mango (Mangifera indica L.) manufacturing in a number of nations together with India (Shukla et al. 2018). Though, a number of fungal pathogens have been reported related to the illness, species of Ceratocystis, Verticillium and Lasiodiplodia have been discovered predominantly chargeable for the wilt (Shukla et al. 2018). A twenty-seven-year outdated mango tree cv. Dashehari at Rehmankhera, Lucknow, Uttar Pradesh, India suffered sudden wilt (Fig. 1A) throughout February 2020. Although, signs have been just like Ceratocystis wilt, no gummosis was noticed on trunk or branches which occurred within the majority of Ceratocystis fimbriata contaminated timber. The contaminated roots of the wilted tree exhibited darkish brown to black discoloration in woody parts (Fig. 1B). Severely affected roots have been utterly rotten.
Related signs of root an infection have been noticed in a further 16 declining timber inside an orchard of 120 timber whole (Fig. 2). The contaminated laborious wooden samples from dwell roots of 16 declining and one wilted timber have been utilized for isolation by putting stem tissue of discolored and regular coloured tissue on floor sterilized contemporary carrot discs positioned in a moisture chamber (Fig. 1C) for 10 days. Out of 17 tree samples, isolates of Berkeleyomyces basicola (Berk. & Broome) W.J. Nel, Z.W. de Beer, T.A. Duong, M.J. Wingf. (Nel et al. 2018) obtained from 1 wilted and 9 declining timber have been transferred to and maintained in pure tradition on potato dextrose agar. Isolates have been grown for 7 to 10 days at 23±1 °C temperature at the hours of darkness. The isolates have been characterised by a greyish black compact mycelial colony (Fig. 1D). Two kinds of spores, endoconidia (phialospores) and chlamydospores (aleuriospores or amylospores) have been noticed below microscope. The endoconidia have been hyaline, cylindrical in form with 10 to 42 × Three to six μm (n=50) in measurement (Fig. 1E). Chains of darkish coloured chlamydospores (Three to 7 spores in chain) of 24 to 52 × 10 to 12 μm (n=50) measurement have been obvious (Fig. 1E&F).
Molecular identification of the fungus remoted from the wilted tree was established by amplifying the ITS1-5.eight rDNA-ITS2 area of fungal genomic DNA and the set of ITS primers (ITS 1 and ITS4) (White et al. 1990) adopted by sequencing. The sequence has been submitted to the NCBI database vide accession quantity MT786402. The current isolate (MT786402) shared >99 p.c nucleotide similarity with different B. basicola isolates. The phylogenetic tree was constructed utilizing the ITS1-5.eight rDNA-ITS2 sequences of different B. basicola isolates and different Thielaviopsis spp., C. fimbriata, Chalaropsis thielavioides by neighbor becoming a member of methodology utilizing MEGAX software program (Fig. 3) (Kumar et al. 2018). The current isolate fashioned a definite cluster together with different B. basicola isolates in a separate clade. Koch’s postulate was carried out below a clear polycarbonate sheet roof internet home at 14.four and 42.2 °C minimal and most temperatures, respectively.
A 100 ml macerated tradition suspension consisting of 1000 chlamydospores and endoconidia per ml suspension was inoculated within the rhizosphere of mango seedlings planted in sterilized soil stuffed in earthen pots, utilizing ten replicates for inoculated and uninoculated vegetation. Signs of necrotic root tissue have been noticed 90 days after inoculation and have been in keeping with these noticed within the area. The identical fungus was re-isolated from contaminated roots and id was confirmed. All management vegetation remained symptom-free and B. basicola was not remoted from the roots. Thus, we conclude that B. basicola is able to inflicting root rot illness of mango. To the most effective of our data that is the primary report of B. basicola inflicting mango root rot and decline throughout the globe, hitherto unreported.
The extent of the basis necrosis signs related to mature mango timber demonstrates the potential virulence of B. basicola, though its pathogenicity threat on wholesome mature timber remains to be unknown. Nevertheless, the potential for extreme losses to the mango trade in world primary mango producer nation, India can’t be dominated out, if discovered widespread.