The mycobiota associated with the weed water hyacinth Pontederia crassipes in Kolkata, India, with emphasis on biological control of the macrophyte

ABSTRACT

The invasive macrophyte water hyacinth, Pontederia crassipes (Mart.) Solms (Pontederiaceae), was first introduced in India at the Acharya Jagadish Chandra Bose Indian Botanic Garden, near Kolkata in 1889 from where they spread throughout the sub-continent. An extensive systematic survey of water bodies in and around Kolkata, India, was done for the first time to assess the natural occurrence of indigenous phytopathogenic fungi of the weed between 2014 and 2019. The study brings into light several species, along with some first reports, of naturally occurring native phytopathogenic fungi and their evolutionary-related lineages. The occurrence and frequency of pathogens varied from site to site. Around 150 fungal pathogens isolated from water hyacinth were evaluated for their disease-causing potential against the weed. The isolated fungi were identified using morphological and molecular techniques. Fusarium Link followed by Alternaria Nees were the highest and most consistently isolated genera. Seven potential fungi that caused more than 90% disease in whole plant pathogenicity bioassay were subjected to host-range evaluation against 67 plant species selected based on ecological nearness or economic significance. Among these Fusarium oxysporum f. sp. lycopersici (WHK-59) was found to have a narrow host range and be effective against water hyacinth. With further studies on their impact assessment, environmental viability and tolerance, few of them, especially F. oxysporum (WHK- 26, 106) may effectively reduce population growth of water hyacinth by themselves or in conjunction with other introduced biocontrol agents, including insects and other plant pathogens.

KEYWORDS:

• Host specificity
• phytopathogen
• survey
• water hyacinth
• microbial control

Acknowledgements

This work forms part of a research project submitted as a Ph.D. dissertation to the Department of Life Sciences, Presidency University, Kolkata. The authors wish to acknowledge Debattam Majumder, Deepa Mal, Jashaswi Basu, Madhurima Sarkar, Parbani Chaudhury, Quoelee Biswas, Ribhu Ray, Shayan Sarkar and Swagata Ghosh for helping us with field surveys from time to time over last six years.

Disclosure statement

No potential conflict of interest was reported by the authors.

Authors’ contribution

W.D. worked throughout the course of the study was involved in each experiment included in the paper and took lead in writing the manuscript. D.M., P.C. and S.D. assisted for short periods and helped during surveys, experiments and maintaining fungal culture. K.M. and J.C.G.P. helped with the statistical analysis of the vast data collected over six years. P.R. conceived the project, the main conceptual ideas, brought in funding for the work and contributed to writing the manuscript.

Additional information

Funding

This research was funded by the grant received from Science and Engineering Research Board, India (Project vide Dairy No. SERB/F/5316/2013-14 dated 18 November 2013); Department of Biotechnology, Govt. of West Bengal (Project No. BT(Estt)/RD 36/2014); UGC Research Awards: 2014–16 (Project Ref. No. F. 30-1/2014/RA-2014-16-GE-MAD-4656 (SAII)); Department of Science and Technology-DST-Inspire Fellowship (No. DST/INSPIRE Fellowship/2015/IF150038).