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Doctor Ramesha H Jayaramaiah

Candidature

Graduated PhD 2023

Thesis Title

Impacts of plant and microbial diversity interactions on key soil functions

Research Project

Interactions between above- and belowground diversity, and their impacts on ecosystem functions

Global change-induced biodiversity loss at all taxonomic levels have raised concern over the consequences of the decline in biodiversity on ecosystem functioning, which ultimately affects human well-being. The current unprecedented rate of biodiversity loss warrants an urgent need for a quantitative understanding of the relationship between biodiversity and ecosystem functioning (BEF). Ecological theories and empirical evidence indicate a positive relationship between plant diversity and rates, resilience and stability of ecosystem functions. Limited reports provide similar evidence for the relationship between microbial diversity and ecosystem functioning, particularly in terrestrial ecosystems. Recent studies also provide considerable evidence that microbial diversity plays essential roles (e.g., decomposition, primary production, detoxification) in maintaining rate and resilience of multiple ecosystem functions and climate change regulation. Above- and belowground diversity are intrinsically linked and may codetermine BEF relationships. Some observational evidence to support such biotic interactions and relative importance of plant and microbial diversity in driving ecosystem multifunctionality has been provided, but experimental evidence is lacking. An investigation of such interactions by manipulative experiments is likely to significantly improve our mechanistic understanding of BEF relationships. Largely, previous studies used either experimentally tested plant or microbial diversity to determine BEF, but not both.  Hence, the relative contribution of above- and belowground diversity and their interactions in driving the rate and resilience of ecosystem functions are largely unexplored.

A number of controlled environment glasshouse experiments and a manipulative field-based experiment will be conducted to simultaneously assess microbial and plant diversity and their functional consequences from microcosm to ecosystem scale. This will include the first experiment to manipulate soil nutrients and plant diversity, or both in soils with contrasting microbial diversity and evaluate its implications on specialized functions (i.e., detoxification). The second experiment to simultaneously manipulate both plant and microbial diversity, and assess their interactive effect on belowground functions (i.e., soil nutrient availability and mineralization). The third experiment to identify the role of plant-microbial diversity interactions in driving multiple ecosystem functions and stability under field conditions with induced drought treatment. Overall, this project will provide key insights on how interactions between above- and belowground diversity and interactions among communities and abiotic properties impact BEF shape and strength. Such information is needed to assess the loss of ecosystem functions caused by global change-induced diversity loss and may potentially inform the development of effective management and policy decisions.

Publications

Jayaramaiah RH, Egidi E, Macdonald CA, Wang JT, Jeffries TC, Megharaj M, Singh BK, (2022) ‘Soil initial bacterial diversity and nutrient availability determine the rate of xenobiotic biodegradation’, Microbial Biotechnology, vol.15, no.1, pp 318–336

Gharat SA, Shinde BA, Mule RD, Punekar SA, Dholakia BB, Jayaramaiah RH, Ramaswamy G, Giri AP, (2020) 'High-throughput metabolomic and transcriptomic analyses vet the potential route of cerpegin biosynthesis in two varieties of Ceropegia bulbosa Roxb.', Planta, vol.251, no.1, Article no.UNSP 28

Gurav TP, Jayaramaiah RH, Punekar SA, Dholakia BB, Giri AP, (2020) 'Generation of novelties in the genus Ocimum as a result of natural hybridization: A morphological, genetical and chemical appraisal', Industrial Crops and Products, vol.156, Article no.112859

Research Supervisors

Professor Brajesh K. Singh, Dr Catriona Macdonald, Dr Eleonora Egidi and Dr Thomas Jeffries