Pranamita Kunda - Academia.edu (original) (raw)

Papers by Pranamita Kunda

World Journal of Microbiology and Biotechnology, 2021

Endophytes have recently garnered importance worldwide and multiple studies are being conducted t... more Endophytes have recently garnered importance worldwide and multiple studies are being conducted to understand their important role and mechanism of interaction inside plants. But before we indulge in their functions it is necessary to dig into the microbiome. This will help to get a complete picture of the microbes intrinsic to their host and understand changes in community composition with respect to their habitats. To ful l this requirement in our study we have attempted to dissect the endophytic diversity in roots of rice plant grown across the various agro-ecological zones of West Bengal by undergoing amplicon analysis of their 16S rRNA gene. We found that the agro-ecological zones can be divided into two groups: nutrient dense (GAZ, NHZ and TTAZ) and nutrient low groups (CSZ, RLZ and VAZ). Few genera (Aeromonas, Sulfurospirillum, Uliginosibacterium, etc.) are present in samples cultivated in all the zones representing the core microbiome of rice in West Bengal while some other genera like Lactococcus, Dickeya, Azonexus, Pectobacterium, etc. are unique to speci c zone. It can be concluded that understanding which particular endophytes cohabit with the internal plant environment can play an important role in endophyte-based stress management strategy. Introduction: Rice is the most important staple food for more than half the world's population. India is one of the leading producers and consumer of rice and the state of West Bengal is one of the highest producers of rice in India (Kunda et al., 2018). However, rice production is impeded by several abiotic and biotic factors. Therefore, to improve the productivity of crops, farmers apply a wide range of chemical fertilizers and pesticides which in excess leave eco-toxic residues in the soil and in longer term, decrease crop productivity (Kumar Bag, 2011). These toxic chemicals are also responsible for global warming and groundwater pollution (Mashiane et al., 2017). To combat these problems, recent developments are being made to use potential microorganisms to manage biotic and abiotic stress and improve plant growth for a healthier environment (Edwards et al., 2015; Mashiane et al., 2017). Microbiomes associated with plants roots are known to play a signi cant role in hastening plant growth, development and can alter plant health as well as their stress tolerance abilities (Lareen et al., 2016). These microbes can reside either in the rhizopsheric soil in close association with the roots or can remain inside the plant as endophytes (Olanrewaju et al., 2017). Symbiotic bacterial endophytes of rice provide multiple bene ts to their host. They adapt different mechanisms to protect plants from various stressful conditions like drought, salinity, pathogen attack (Khare et al., 2018; Mukhtar et al., 2019). They do so by increasing carbon and nitrogen metabolism, enhancing photosynthetic activity as well as detoxifying enzymes activities, reducing damage caused by reactive oxygen species, producing osmotic regulators, ACC deaminase enzyme, various phytohormones and also by inducing systemic resistance in plants (Edwards et al., 2015; Taulé et al., 2021; Y. Zhang et al., 2019). Root exudates from plants also trigger up-regulation of genes in bacteria that are involved in transporters, e ux pumps and enzymes. It has been observed that plant-associated bacteria tend to have larger genome than non-plant associated species (Pini et al., 2011) and these genes are mainly related to transport, regulation, sugar metabolism, nodulation, etc. (Checcucci et al., 2017). At present, little information is available for plant-microbes interaction at molecular level since it is not a typical "gene-for-gene" interaction (Nautiyal et al., 2013). Therefore, studying plant-microbe relationship can be highly advantageous in establishing a sustainable plant root microbiome system. For better understanding of the mechanisms of interaction between plants and microbes it is imperative to identify the plant endophytic microbiomes (Kunda et al., 2018). Hence, studying endophytic diversity becomes the foremost requisite in plant-microbe interaction. Since bacteria has established a close bilateral interaction with its surrounding environment, study of bacterial diversity plays a crucial role in understanding biodiversity-ecosystem functioning (Kang et al., 2006) and various plant-related process (Kumar et al., 2018). This knowledge will also provide information about the core microbiome of a particular region that can help plants sustain challenging environments. Recently, culture independent 16S rRNA gene based sequencing are being performed to gain knowledge of endophytic bacterial composition in different economically important crop plants like maize, potato, tomato, tobacco and soybean (Lei et al., 2019). These studies have helped us to gather some knowledge about bacterial diversity, community and composition inside the plants and its relation with soil microbiome (Edwards et al., 2015). However, all these interpretations/studies are at a nascent stage and more in depth knowledge are required to answer all the queries (Pinski et al., 2019). Regarding study of rice endophytic bacteria a lot of work has been done on isolation and characterization of endophytic bacterial isolates and their potential role in promoting plant growth under diverse conditions (Hardoim et al., 2011; Kang et al., 2006; Moronta-Barrios et al., 2018). Studies on total microbial diversity using metagenomic methods have provided knowledge on rice endosphere composition and function (Sessitsch et al., 2012) as well as their dynamic changes. But in India, work on bacterial diversity of rice are either based on diversity of rice seed endophytes (Chaudhry et al., 2017; Verma et al., 2001) or from rice plants grown under aerobic condition (Vishwakarma & Dubey, 2020), or from particular varieties (Banik et al., 2017.; Sengupta et al., 2017) or bacteria isolated from rice root rhizosphere (Arjun & Harikrishnan, 2011). These works are mainly one dimensional focussing on a single site with limited sample numbers. Even though endophytic microbes of many plants are being studied but our knowledge on endophytic bacterial ecology of rice is limited. Ahn et al. (2016), also con rmed that the abundance and diversity of microbes in rice elds that affect crop growth are not well documented (Ahn et al., 2016). Therefore, the main aim of our study was to provide information regarding the rice endophytic community across different agro-ecological zones in West Bengal, i.e. a representation of the rice bacterial endophytes in the state. Since agro-ecological zones are diverse, this study will provide a baseline on various endophytes that colonize rice plants grown throughout West Bengal. West Bengal being one of the highest producers of rice its endophytic community is not explored properly yet (Kunda et al., 2018). There are no reports available so far as per our knowledge on the endophytic bacterial community of rice across the different regions of this state. As our sampling covers different ecological zones, we hypothesized that different endophytic communities will colonize rice plants due to the in uence of the environmental variables that characterize these ecological regions. In West Bengal, which can be broadly divided into six agro-ecological zones, rice is cultivated in almost all the zones (Kumar Bag, 2011). But the regions comprising the old and new alluvial soil i.e. Gangetic Alluvial zone and Vindhyan Alluvial zone are the main rice producing areas (Ghosh et al., 2005). The western part of West Bengal, comprising the Red and Laterite zone are made up of undulating lands with isolated peaks and at plains which in general are drought prone regions whereas the extreme southern part has Coastal Saline zone which is frequently washed by brackish water from the Bay of Bengal (Kumar Bag, 2011). Rice production is affected in these regions due to various abiotic stress conditions like salinity and drought.

Microbial Mitigation of Stress Response of Food Legumes, 2020

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences, 2021

Bacillus cereus is a spore-forming bacterial species that has some pathogenic strains responsible... more Bacillus cereus is a spore-forming bacterial species that has some pathogenic strains responsible for several human diseases. The present study was aimed to characterize a pathogenic strain of B. cereus WBI3 isolated from pond water of rural Tinna village area of West Bengal and its control by plant products. Out of the four screened bacterial isolates, WBI3 was found to possess haemolytic character. The bacterial strain WBI3 was gram-positive, spore forming, rod-shaped, motile bacterium, positive for catalase, oxidase, methyl red and nitrate reduction test and negative for indole, urease, citrate and Voges–Proskauer test. Bacterial isolate WBI3 was capable of producing amylase, lipase and gelatinase enzymes and was able to ferment trehalose, dextrose, fructose and salicin. Among twenty standard antibiotics, the bacterium was sensitive to seventeen antibiotics but resistant to three antibiotics. Morphological, biochemical and molecular analyses of the bacterial strain WBI3 indicated that it was a haemolytic and penicillin-resistant strain of B. cereus. Among six tested plant extracts, aqueous and alcoholic (methanolic and ethanolic) extracts of Acacia nilotica showed significant antibacterial activity against B. cereus WBI3 and inhibition zone diameters were 21.66 ± 1.52 mm, 25.33 ± 0.57 mm and 22.33 ± 1.52 mm, respectively. Further studies are needed to identify the bioactive compounds which have an antagonistic role against this pathogenic strain, so that a formulation can be made which would help to control the bacterial strain in the water bodies and spreading of diseases caused by this strain.

Meta Gene, 2018

Rice is one of the most important cereal crops and a staple food for more than half of the world'... more Rice is one of the most important cereal crops and a staple food for more than half of the world's population and West Bengal is its leading producer in India. But several abiotic conditions, like draught, soil salinity affect rice productivity. A novel approach using endophytic bacteria to ameliorate various stress conditions is gaining popularity for the betterment of agriculture. However, work on endophytic bacteria isolated from rice has not been properly evaluated in India. In this study we wanted to explore the diversity of bacterial endophytes inhabiting roots of rice plants growing in the Coastal saline zone of Sundarbans, West Bengal. This has been achieved through amplicon metagenomics of bacterial 16S rRNA gene in the IlluminaMiSeq platform. In our investigation endophytic bacterial community was exclusively dominated by the order Rickettsiales followed by Enterobacteriales. Our result identified the genera, some of whom have potential plant growth promotion (PGP) abilities as well as role in defense mechanisms of plants (viz. Pantoea, Enterobacter, Paenibacillus, etc.). Few genera (viz. Aerinimonas, Arcobacter, Chitinophaga, Hydrogenispora, Sulfospirillum, etc.) identified in our study have not been reported previously as endophytes and most probably are unique endophytes of this region. This study has enumerated the diversity of endophytic bacteria from rice grown in the saline zone of West Bengal that would help us to design a better strategy for cultivation under abiotic stress condition.

Plant Physiology and Biochemistry, 2012

The effect of common salt (NaCl) on ion contents, Krebs cycle intermediates and its regulatory en... more The effect of common salt (NaCl) on ion contents, Krebs cycle intermediates and its regulatory enzymes was investigated in growing mungbean (Vigna radiata L. Wilczek, B 105) seedlings. Sodium and chloride ion contents increased in both root and shoot whereas potassium ion content decreased in shoot of test seedlings with increasing concentrations of NaCl. Organic acids like pyruvate and citrate levels increased whereas malate level decreased under stress in both roots and shoots. Salt stress also variedly affected the activities of different enzymes of respiratory chain. The activity of pyruvate dehydrogenase (E.C. 1.2.4.1) decreased in 50 mM NaCl but increased in 100 mM and 150 mM concentrations, in both root and shoot samples. Succinate dehydrogenase (E.C. 1.3.5.1) activity was reduced in root whereas stimulated in shoot under increasing concentrations of salt. The activity of isocitrate dehydrogenase (E.C. 1.1.1.41) and malate dehydrogenase (E.C. 1.1.1.37) decreased in both root and shoot samples under salt stress. On the contrary, pretreatment of mungbean seeds with sublethal dose of NaCl was able to overcome the adverse effects of stress imposed by NaCl to variable extents with significant alterations of all the tested parameters, resulting in better growth and efficient respiration in mungbean seedlings. Thus, plants can acclimate to lethal level of salinity by pretreatment of seeds with sublethal level of NaCl, which serves to improve their health and production under saline condition, but the sublethal concentration of NaCl should be carefully chosen.

World Journal of Microbiology and Biotechnology, 2021

Endophytes have recently garnered importance worldwide and multiple studies are being conducted t... more Endophytes have recently garnered importance worldwide and multiple studies are being conducted to understand their important role and mechanism of interaction inside plants. But before we indulge in their functions it is necessary to dig into the microbiome. This will help to get a complete picture of the microbes intrinsic to their host and understand changes in community composition with respect to their habitats. To ful l this requirement in our study we have attempted to dissect the endophytic diversity in roots of rice plant grown across the various agro-ecological zones of West Bengal by undergoing amplicon analysis of their 16S rRNA gene. We found that the agro-ecological zones can be divided into two groups: nutrient dense (GAZ, NHZ and TTAZ) and nutrient low groups (CSZ, RLZ and VAZ). Few genera (Aeromonas, Sulfurospirillum, Uliginosibacterium, etc.) are present in samples cultivated in all the zones representing the core microbiome of rice in West Bengal while some other genera like Lactococcus, Dickeya, Azonexus, Pectobacterium, etc. are unique to speci c zone. It can be concluded that understanding which particular endophytes cohabit with the internal plant environment can play an important role in endophyte-based stress management strategy. Introduction: Rice is the most important staple food for more than half the world's population. India is one of the leading producers and consumer of rice and the state of West Bengal is one of the highest producers of rice in India (Kunda et al., 2018). However, rice production is impeded by several abiotic and biotic factors. Therefore, to improve the productivity of crops, farmers apply a wide range of chemical fertilizers and pesticides which in excess leave eco-toxic residues in the soil and in longer term, decrease crop productivity (Kumar Bag, 2011). These toxic chemicals are also responsible for global warming and groundwater pollution (Mashiane et al., 2017). To combat these problems, recent developments are being made to use potential microorganisms to manage biotic and abiotic stress and improve plant growth for a healthier environment (Edwards et al., 2015; Mashiane et al., 2017). Microbiomes associated with plants roots are known to play a signi cant role in hastening plant growth, development and can alter plant health as well as their stress tolerance abilities (Lareen et al., 2016). These microbes can reside either in the rhizopsheric soil in close association with the roots or can remain inside the plant as endophytes (Olanrewaju et al., 2017). Symbiotic bacterial endophytes of rice provide multiple bene ts to their host. They adapt different mechanisms to protect plants from various stressful conditions like drought, salinity, pathogen attack (Khare et al., 2018; Mukhtar et al., 2019). They do so by increasing carbon and nitrogen metabolism, enhancing photosynthetic activity as well as detoxifying enzymes activities, reducing damage caused by reactive oxygen species, producing osmotic regulators, ACC deaminase enzyme, various phytohormones and also by inducing systemic resistance in plants (Edwards et al., 2015; Taulé et al., 2021; Y. Zhang et al., 2019). Root exudates from plants also trigger up-regulation of genes in bacteria that are involved in transporters, e ux pumps and enzymes. It has been observed that plant-associated bacteria tend to have larger genome than non-plant associated species (Pini et al., 2011) and these genes are mainly related to transport, regulation, sugar metabolism, nodulation, etc. (Checcucci et al., 2017). At present, little information is available for plant-microbes interaction at molecular level since it is not a typical "gene-for-gene" interaction (Nautiyal et al., 2013). Therefore, studying plant-microbe relationship can be highly advantageous in establishing a sustainable plant root microbiome system. For better understanding of the mechanisms of interaction between plants and microbes it is imperative to identify the plant endophytic microbiomes (Kunda et al., 2018). Hence, studying endophytic diversity becomes the foremost requisite in plant-microbe interaction. Since bacteria has established a close bilateral interaction with its surrounding environment, study of bacterial diversity plays a crucial role in understanding biodiversity-ecosystem functioning (Kang et al., 2006) and various plant-related process (Kumar et al., 2018). This knowledge will also provide information about the core microbiome of a particular region that can help plants sustain challenging environments. Recently, culture independent 16S rRNA gene based sequencing are being performed to gain knowledge of endophytic bacterial composition in different economically important crop plants like maize, potato, tomato, tobacco and soybean (Lei et al., 2019). These studies have helped us to gather some knowledge about bacterial diversity, community and composition inside the plants and its relation with soil microbiome (Edwards et al., 2015). However, all these interpretations/studies are at a nascent stage and more in depth knowledge are required to answer all the queries (Pinski et al., 2019). Regarding study of rice endophytic bacteria a lot of work has been done on isolation and characterization of endophytic bacterial isolates and their potential role in promoting plant growth under diverse conditions (Hardoim et al., 2011; Kang et al., 2006; Moronta-Barrios et al., 2018). Studies on total microbial diversity using metagenomic methods have provided knowledge on rice endosphere composition and function (Sessitsch et al., 2012) as well as their dynamic changes. But in India, work on bacterial diversity of rice are either based on diversity of rice seed endophytes (Chaudhry et al., 2017; Verma et al., 2001) or from rice plants grown under aerobic condition (Vishwakarma & Dubey, 2020), or from particular varieties (Banik et al., 2017.; Sengupta et al., 2017) or bacteria isolated from rice root rhizosphere (Arjun & Harikrishnan, 2011). These works are mainly one dimensional focussing on a single site with limited sample numbers. Even though endophytic microbes of many plants are being studied but our knowledge on endophytic bacterial ecology of rice is limited. Ahn et al. (2016), also con rmed that the abundance and diversity of microbes in rice elds that affect crop growth are not well documented (Ahn et al., 2016). Therefore, the main aim of our study was to provide information regarding the rice endophytic community across different agro-ecological zones in West Bengal, i.e. a representation of the rice bacterial endophytes in the state. Since agro-ecological zones are diverse, this study will provide a baseline on various endophytes that colonize rice plants grown throughout West Bengal. West Bengal being one of the highest producers of rice its endophytic community is not explored properly yet (Kunda et al., 2018). There are no reports available so far as per our knowledge on the endophytic bacterial community of rice across the different regions of this state. As our sampling covers different ecological zones, we hypothesized that different endophytic communities will colonize rice plants due to the in uence of the environmental variables that characterize these ecological regions. In West Bengal, which can be broadly divided into six agro-ecological zones, rice is cultivated in almost all the zones (Kumar Bag, 2011). But the regions comprising the old and new alluvial soil i.e. Gangetic Alluvial zone and Vindhyan Alluvial zone are the main rice producing areas (Ghosh et al., 2005). The western part of West Bengal, comprising the Red and Laterite zone are made up of undulating lands with isolated peaks and at plains which in general are drought prone regions whereas the extreme southern part has Coastal Saline zone which is frequently washed by brackish water from the Bay of Bengal (Kumar Bag, 2011). Rice production is affected in these regions due to various abiotic stress conditions like salinity and drought.

Microbial Mitigation of Stress Response of Food Legumes, 2020

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences, 2021

Bacillus cereus is a spore-forming bacterial species that has some pathogenic strains responsible... more Bacillus cereus is a spore-forming bacterial species that has some pathogenic strains responsible for several human diseases. The present study was aimed to characterize a pathogenic strain of B. cereus WBI3 isolated from pond water of rural Tinna village area of West Bengal and its control by plant products. Out of the four screened bacterial isolates, WBI3 was found to possess haemolytic character. The bacterial strain WBI3 was gram-positive, spore forming, rod-shaped, motile bacterium, positive for catalase, oxidase, methyl red and nitrate reduction test and negative for indole, urease, citrate and Voges–Proskauer test. Bacterial isolate WBI3 was capable of producing amylase, lipase and gelatinase enzymes and was able to ferment trehalose, dextrose, fructose and salicin. Among twenty standard antibiotics, the bacterium was sensitive to seventeen antibiotics but resistant to three antibiotics. Morphological, biochemical and molecular analyses of the bacterial strain WBI3 indicated that it was a haemolytic and penicillin-resistant strain of B. cereus. Among six tested plant extracts, aqueous and alcoholic (methanolic and ethanolic) extracts of Acacia nilotica showed significant antibacterial activity against B. cereus WBI3 and inhibition zone diameters were 21.66 ± 1.52 mm, 25.33 ± 0.57 mm and 22.33 ± 1.52 mm, respectively. Further studies are needed to identify the bioactive compounds which have an antagonistic role against this pathogenic strain, so that a formulation can be made which would help to control the bacterial strain in the water bodies and spreading of diseases caused by this strain.

Meta Gene, 2018

Rice is one of the most important cereal crops and a staple food for more than half of the world'... more Rice is one of the most important cereal crops and a staple food for more than half of the world's population and West Bengal is its leading producer in India. But several abiotic conditions, like draught, soil salinity affect rice productivity. A novel approach using endophytic bacteria to ameliorate various stress conditions is gaining popularity for the betterment of agriculture. However, work on endophytic bacteria isolated from rice has not been properly evaluated in India. In this study we wanted to explore the diversity of bacterial endophytes inhabiting roots of rice plants growing in the Coastal saline zone of Sundarbans, West Bengal. This has been achieved through amplicon metagenomics of bacterial 16S rRNA gene in the IlluminaMiSeq platform. In our investigation endophytic bacterial community was exclusively dominated by the order Rickettsiales followed by Enterobacteriales. Our result identified the genera, some of whom have potential plant growth promotion (PGP) abilities as well as role in defense mechanisms of plants (viz. Pantoea, Enterobacter, Paenibacillus, etc.). Few genera (viz. Aerinimonas, Arcobacter, Chitinophaga, Hydrogenispora, Sulfospirillum, etc.) identified in our study have not been reported previously as endophytes and most probably are unique endophytes of this region. This study has enumerated the diversity of endophytic bacteria from rice grown in the saline zone of West Bengal that would help us to design a better strategy for cultivation under abiotic stress condition.

Plant Physiology and Biochemistry, 2012

The effect of common salt (NaCl) on ion contents, Krebs cycle intermediates and its regulatory en... more The effect of common salt (NaCl) on ion contents, Krebs cycle intermediates and its regulatory enzymes was investigated in growing mungbean (Vigna radiata L. Wilczek, B 105) seedlings. Sodium and chloride ion contents increased in both root and shoot whereas potassium ion content decreased in shoot of test seedlings with increasing concentrations of NaCl. Organic acids like pyruvate and citrate levels increased whereas malate level decreased under stress in both roots and shoots. Salt stress also variedly affected the activities of different enzymes of respiratory chain. The activity of pyruvate dehydrogenase (E.C. 1.2.4.1) decreased in 50 mM NaCl but increased in 100 mM and 150 mM concentrations, in both root and shoot samples. Succinate dehydrogenase (E.C. 1.3.5.1) activity was reduced in root whereas stimulated in shoot under increasing concentrations of salt. The activity of isocitrate dehydrogenase (E.C. 1.1.1.41) and malate dehydrogenase (E.C. 1.1.1.37) decreased in both root and shoot samples under salt stress. On the contrary, pretreatment of mungbean seeds with sublethal dose of NaCl was able to overcome the adverse effects of stress imposed by NaCl to variable extents with significant alterations of all the tested parameters, resulting in better growth and efficient respiration in mungbean seedlings. Thus, plants can acclimate to lethal level of salinity by pretreatment of seeds with sublethal level of NaCl, which serves to improve their health and production under saline condition, but the sublethal concentration of NaCl should be carefully chosen.