Browsing by Author "Kanchan Kumar"

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Application of bacterial biostimulants in promoting growth and disease prevention in crop plants
(Elsevier, 2021) Gaurav Pal; Kanchan Kumar; Anand Verma; Satish K. Verma
Biological-based substances, other than commercially used chemical fertilizers and pesticides, which have the capability to induce plant development and protect them from stressful situations, are called as biostimulants. The application of biostimulants in present times is needed for safe, eco-friendly agriculture, and is the base of organic farming. One of the major categories of biostimulants includes beneficial microorganisms constituting of bacterial and fungal cell inoculants and their products. Many plants-associated microbes are mutualistic symbionts of crop plants which improve their fitness and productivity by nutrient mobilization, nitrogen fixation, phytohormone production, and producing a variety of antipathogenic chemicals. These microbial symbionts and their stimulatory products may also induce host-related genes and provide tolerance against abiotic and biotic stresses. In this chapter, we will discuss the bacterial biostimulants and their role in plant growth and development, and protection from diseases. © 2021 Elsevier Inc.
Endophytic Burkholderia: Multifunctional roles in plant growth promotion and stress tolerance
(Elsevier GmbH, 2022) Gaurav Pal; Samiksha Saxena; Kanchan Kumar; Anand Verma; Pramod K. Sahu; Ashutosh Pandey; James F. White; Satish K. Verma
The genus Burkholderia has proven potential in improving plant performance. In recent decades, a huge diversity of Burkholderia spp. have been reported with diverse capabilities of plant symbiosis which could be harnessed to enhance plant growth and development. Colonization of endophytic Burkholderia spp. have been extensively studied through techniques like advanced microscopy, fluorescent labelling, PCR based assays, etc., and found to be systemically distributed in plants. Thus, use of these biostimulant microbes holds the promise of improving quality and quantity of crops. The endophytic Burkholderia spp. have been found to support plant functions along with boosting nutrient availability, especially under stress. Endophytic Burkholderia spp. improve plant survival against deadly pathogens via mechanisms like competition, induced systemic resistance, and antibiosis. At the same time, they are reported to extend plant tolerance towards multiple abiotic stresses especially drought, salinity, and cold. Several attempts have been made to decipher the potential of Burkholderia spp. by genome mining, and these bacteria have been found to harbour genes for plant symbiosis and for providing multiple benefits to host plants. Characteristics specific for host recognition and nutrient acquisition were confirmed in endophytic Burkholderia by genomics and proteomics-based studies. This could pave the way for harnessing Burkholderia spp. for biotechnological applications like biotransformation, phytoremediation, insecticidal activity, antimicrobials, etc. All these make Burkholderia spp. a promising microbial agent in improving plant performance under multiple adversities. Thus, the present review highlights critical roles of endophytic Burkholderia spp., their colonization, alleviation of biotic and abiotic stresses, biotechnological applications and genomic insights. © 2022 Elsevier GmbH
Functional roles of seed-inhabiting endophytes of rice
(Springer International Publishing, 2019) Gaurav Pal; Kanchan Kumar; Anand Verma; James Francis White; Satish K. Verma
Endophytic microbes including bacteria and fungi inhabiting in seed tissues have recently gained significant importance owing to a diversity of roles that they play and eventually resulting in improved plant growth as well as plant fitness. Some of the major roles played by seed endophytic microbes include plant growth promotion by enhanced nutrient acquisition or production of growth hormones, nitrogen fixation, phosphate solubilisation, and protection against pathogens as well as abiotic stresses. Since, rice is one of the important staple crop across the globe, there is a great need to explore and decipher the roles of the endophytic community present inside it. This chapter focuses on the diversity and distribution of rice seed endophytes, their transmission along with the various functional roles that they play inside the plants with an aim to provide deep insights on rice seed endophytes as plant growth promoting and biocontrol agents. © Springer Nature Switzerland AG 2019.
Seed Endophytic Bacteria of Pearl Millet (Pennisetum glaucum L.) Promote Seedling Development and Defend Against a Fungal Phytopathogen
(Frontiers Media S.A., 2021) Kanchan Kumar; Anand Verma; Gaurav Pal; Anubha; James F. White; Satish K. Verma
Seed endophytic bacteria (SEB) are primary symbionts that play crucial roles in plant growth and development. The present study reports the isolation of seven culturable SEB including Kosakonia cowanii (KAS1), Bacillus subtilis (KAS2), Bacillus tequilensis (KAS3), Pantoea stewartii (KAS4), Paenibacillus dendritiformis (KAS5), Pseudomonas aeruginosa (KAS6), and Bacillus velezensis (KAS7) in pearl millet seeds. All the isolates were characterized for their plant growth promoting activities. Most of the SEB also inhibited the growth of tested fungal phytopathogens in dual plate culture. Removal of these SEB from seeds compromised the growth and development of seedlings, however, re-inoculation with the SEB (Kosakonia cowanii, Pantoea stewartii, and Pseudomonas aeruginosa) restored the growth and development of seedlings significantly. Fluorescence microscopy showed inter and intracellular colonization of SEB in root parenchyma and root hair cells. Lipopeptides were extracted from all three Bacillus spp. which showed strong antifungal activity against tested fungal pathogens. Antifungal lipopeptide genes were also screened in Bacillus spp. After lipopeptide treatment, live-dead staining with fluorescence microscopy along with bright-field and scanning electron microscopy (SEM) revealed structural deformation and cell death in Fusarium mycelia and spores. Furthermore, the development of pores in the membrane and leakages of protoplasmic substances from cells and ultimately death of hyphae and spores were also confirmed. In microcosm assays, treatment of seeds with Bacillus subtilis or application of its lipopeptide alone significantly protected seedlings from Fusarium sp. infection. Copyright © 2021 Kumar, Verma, Pal, Anubha, White and Verma.
Seed endophytic bacterium Bacillus velezensis and its lipopeptides acts as elicitors of defense responses against Fusarium verticillioides in maize seedlings
(Springer Science and Business Media Deutschland GmbH, 2023) Gaurav Pal; Samiksha Saxena; Kanchan Kumar; Anand Verma; Deepak Kumar; Pooja Shukla; Ashutosh Pandey; Satish K. Verma
Purpose: The potential of endophytic bacteria to improve plant health has been well-established. In maize plants, studies have reported the antagonistic activity of endophytic bacteria against various kinds of phytopathogenic strains; however, the effect of lipopeptide inoculation on germinated seedlings and its underlying defense responses remain unexplored. In this study, we examined the effects of seed endophytic bacterium Bacillus velezensis and its lipopeptides in improving plant defense against Fusarium verticillioides in maize seedlings. Methods: In vitro germinated maize seedlings were treated with lipopeptides extracted from the B. velezensis, followed by inoculation with the phytopathogen Fusarium verticillioides. The lipopeptides were characterized using MALDI-TOF analysis and their effects on fungal colonization and defense gene expression were investigated. Polyphenol content was checked in the bacterium-ZMW8 as well as ZMW8 and Fusarium-inoculated seedlings through UHPLC. Results: Lipopeptide treatment to the maize seedling’s roots resulted in enhanced protection from the fungus with significant improvement in all the growth parameters measured. Antifungal lipopeptides were identified as bacillomycin D and fengycin. Confocal microscopy images revealed the heavy colonization of fungus on the seed and root surface of non-lipopeptide-treated seedlings. Gene expression analysis revealed upregulation of various defense response genes including ZmPR-1, ZmPR-4, ZmSOD-2, ZmLOX, ZmPDF1.2, and ZmERF in the roots of bacteria and lipopeptides-treated maize seedlings. Targeted metabolite analysis through UHPLC revealed the accumulation of antifungal polyphenols including p-coumaric acid, kaempferol, dihydrokaempferol (DHK), and dihydroquercetin (DHQ). Conclusions: The study highlights the potential of bacterial lipopeptides as elicitors of defense responses in maize seedlings against Fusarium infection. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
Seed endophytic bacterium Lysinibacillus sp. (ZM1) from maize (Zea mays L.) shapes its root architecture through modulation of auxin biosynthesis and nitrogen metabolism
(Elsevier Masson s.r.l., 2024) Gaurav Pal; Samiksha Saxena; Kanchan Kumar; Anand Verma; Deepak Kumar; Pooja Shukla; Ashutosh Pandey; James White; Satish K. Verma
Seed endophytic bacteria have been shown to promote the growth and development of numerous plants. However, the underlying mechanism still needs to be better understood. The present study aims to investigate the role of a seed endophytic bacterium Lysinibacillus sp. (ZM1) in promoting plant growth and shaping the root architecture of maize seedlings. The study explores how bacteria-mediated auxin biosynthesis and nitrogen metabolism affect plant growth promotion and shape the root architecture of maize seedlings. The results demonstrate that ZM1 inoculation significantly enhances root length, root biomass, and the number of seminal roots in maize seedlings. Additionally, the treated seedlings exhibit increased shoot biomass and higher levels of photosynthetic pigments. Confocal laser scanning microscopy (CLSM) analysis revealed extensive colonization of ZM1 on root hairs, as well as in the cortical and stellar regions of the root. Furthermore, LC-MS analysis demonstrated elevated auxin content in the roots of the ZM1 treated maize seedlings compared to the uninoculated control. Inoculation with ZM1 significantly increased the levels of endogenous ammonium content, GS, and GOGAT enzyme activities in the roots of treated maize seedlings compared to the control, indicating enhanced nitrogen metabolism. Furthermore, inoculation of bacteria under nitrogen-deficient conditions enhanced plant growth, as evidenced by increased root shoot length, fresh and dry weights, average number of seminal roots, and content of photosynthetic pigments. Transcript analysis indicated upregulation of auxin biosynthetic genes, along with genes involved in nitrogen metabolism at different time points in roots of ZM1-treated maize seedlings. Collectively, our findings highlight the positive impact of Lysinibacillus sp. ZM1 inoculation on maize seeds by improving root architecture through modulation of auxin biosynthesis and affecting various nitrogen metabolism related parameters. These findings provide valuable insights into the potential utilization of seed endophytic bacteria as biofertilizers to enhance plant growth and yield in nutrient deficient soils. © 2024 Elsevier Masson SAS
Seed inhabiting bacterial endophyte Bacillus amyloliquefaciens (SS7) defends sorghum Sudan grass seedlings from a phytopathogen Rhizoctonia solani
(Springer Science and Business Media B.V., 2025) Kanchan Kumar; Deepak Kumar; Gaurav Pal; Satish K. Verma
Seeds naturally harbour bacterial endophytes that act as primary symbionts of plants. This study aimed to isolate and characterise seed inhabiting bacterial endophytes of sorghum sudan grass and evaluate the most active endophyte, Bacillus amyloliquefaciens-SS7 for protecting seedlings against Rhizoctonia solani infection. Seven bacterial endophytes (SS1-SS7) were isolated from surface sterilized sorghum sudan grass seeds and identified via 16 S rRNA sequencing. All isolates were screened for plant growth promoting and antifungal activities. B. amyloliquefaciens-SS7 exhibited the highest siderophore production and strong antifungal activity. Gene screening confirmed the presence of antifungal lipopeptide genes (Iturin A and Bacillomycin D) in B. amyloliquefaciens. Extracted lipopeptides from B. amyloliquefaciens strongly inhibited R. solani in disc diffusion assays. Bright field and fluorescence microscopy revealed that lipopeptides caused structural deformations and cell death in R. solani. Microcosm assays demonstrated significant protection of seedlings inoculated with B. amyloliquefaciens from Rhizoctonia infection. Histological studies confirmed overproduction of superoxide ions and cell death in seedlings infected with R. solani. Biochemical analysis showed increased levels of phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD), and peroxidase (POX) in treated seedlings compared controls. Infections caused by R. solani targeted the collar region of seedlings, causing damping-off in those lacking the endophyte B. amyloliquefaciens. This study concludes that sorghum sudan grass seeds contain bacteria like B. amyloliquefaciens-SS7, which are crucial in protecting seedlings from R. solani. This research is the first to report on the role of seed endophytic bacteria (SEB) in the protecting sorghum sudan grass against R. solani. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.
Seed inhabiting bacterial endophytes of finger millet (Eleusine coracana L.) promote seedling growth and development, and protect from fungal disease
(Elsevier B.V., 2020) Kanchan Kumar; Gaurav Pal; Anand Verma; Satish Kumar Verma
The goal of this study was to evaluate the role of seed inhabiting bacterial endophytes on finger millet seedling development and protection from fungal infection. This study has shown that removal of endophytic bacteria from millet seeds compromised seedling health, however, re-inoculation of the same bacterial isolates restored its growth. A total of six endophytic bacteria were isolated from surface-sterilized seeds of finger millet and molecularly identified by 16S rDNA sequencing as Paenibacillus dendritiformis (EC1), Enterobacter hormaechei (EC2), Enterobacter cloacae (EC3), Bacillus safensis (EC4), Enterobacter hormaechei (EC5), and Enterobacter hormaechei (EC6). These isolated endophytes were tested for their plant growth-promoting activities. Enterobacter strains (EC2, EC3, EC5 and EC6) were found positive for IAA (Indole acetic acid) test and showed phosphate as well as potassium solubilization activities while siderophore production was shown by EC1 and EC4. Antifungal activity was also evaluated with isolate EC1 showing inhibition against all the tested phytopathogens. In seedling protection assay, bacterial endophytes significantly reduced the infection from Fusarium oxysporum. Re-inoculation experiment was carried out and it was found that bacterial strains EC1, EC4, and EC5 were most active in seedling development of finger millet, showing considerable improvement in root-shoot lengths, fresh weights and content of chlorophyll pigments. Endophytic bacterial colonization in the seedling roots was observed using fluorescent microscopy. This study reports the presence of endophytic bacteria inside seeds of finger millet having stimulatory effects on its growth and development. © 2020 SAAB
Seed inhabiting bacterial endophytes of maize promote seedling establishment and provide protection against fungal disease
(Elsevier GmbH, 2022) Gaurav Pal; Kanchan Kumar; Anand Verma; Satish Kumar Verma
Bacteria from different crops and plant varieties have been shown to possess enormous growth promotional attributes. The study aimed to investigate the role of the endophytic microbiome of seeds of corn in improving the growth of seedlings of two different varieties of maize crops (K-25 and baby corn). Furthermore, the study also assessed the role of these bacteria in the protection of seedlings from fungal pathogens. Total twenty-three endophytic bacterial strains were isolated from maize seeds and identified using 16S rDNA sequencing. Most of the isolates had the ability to synthesize auxin (70 %) and solubilize phosphate (74 %), while all the isolates showed nitrogen fixation ability. Some isolates also showed antagonistic activity against phytopathogenic fungi including Rhizoctonia solani and Fusarium sp. suggesting their biocontrol potential. The presence of different lipopeptide genes including bacillomycin D, fengycin, iturin A and surfactin was confirmed in some of the isolates. We observed that treating seeds with an antibiotic compromised the seedlings’ growth; however, re-inoculation with endophytic isolates (ZM1/Lysinibacillus sp. and ZM2/Paenibacillus dendritiformis) restored the growth of the seedlings in terms of improved root and shoot development in comparison to non-inoculated controls. The colonization of inoculated bacteria on the root surface was visualized using fluorescent microscopy. Seedling protection assay showed that treated seeds (with ZMW8/ Bacillus velezensis) were protected from fungal infestation (Fusarium verticillioides) even after 12 days of inoculation in comparison to the uninoculated control. The study concludes that indigenous seed-associated bacteria of maize play a major role during seed germination, seedling formation and protect them from phytopathogens. © 2021 Elsevier GmbH
Seed vectored bacterial endophyte Bacillus pumilus protect sorghum (Sorghum bicolor L.) seedlings from a fungal pathogen Rhizoctonia solani
(Academic Press Inc., 2023) Kanchan Kumar; Gaurav Pal; Anand Verma; Deepak Kumar; Pooja Shukla; Satish K. Verma
The goal of this study was to evaluate the role of seed endophytic bacteria (SEB) in fungal disease protection in sorghum seedlings. Total six SEB, including two Bacillus spp. (SM1 and SM6), and four Paenibacillus spp. (SM2, SM3, SM4, and SM5) were isolated from sorghum seeds. All isolates produced auxin while only SM3 isolate showed phosphate solubilization activity. All SEB inhibited the growth of tested fungal pathogens. Bacillus pumilus (SM1) and Bacillus subtilis (SM6) showed positive drop collapse assay, and presence of surfactin gene was also screened in their genomes. Further, lipopeptides extracted from SM1 and SM6 strongly inhibited Rhizoctonia solani growth in disc diffusion assay. Live-dead staining and fluorescence microscopy revealed the structural deformations and cell death in R. solani by lipopeptides. In microcosm assay, seeds inoculated with B. pumilus significantly protected the seedlings from Rhizoctonia infection. B. pumilus inoculated seedlings showed significant increase in the levels of PAL and SOD enzymes and their gene expressions (2.76, 2.00 and 4.61, 2.25 folds, respectively) compared to control. PR1 gene expression was also increased by 2.68 folds compared to the control. Present study concludes that sorghum seeds inhabit SEB like B. pumilus which is crucial in protecting seedlings from R. solani by producing lipopeptides, enhancing antioxidant and defense enzymes level and their gene expressions. This study is significant in terms of its originality which presents a first report on SEB of sorghum roles in seedlings protection against soil borne fungal pathogen like Rhizoctonia solani. © 2023 Elsevier Inc.
Seed-inhabiting endophytes: Their role in plant development and disease protection
(Elsevier, 2020) Gaurav Pal; Kanchan Kumar; Anand Verma; R.N. Kharwar; Satish K. Verma
Plants might have successfully originated and evolved through acquiring intimate interactions with microbes. Some of these microbes are endophytic and mutualistic to host plant and have been a source of various adaptive advantages for hosts, for example, in induction of developmental functions under stress conditions. Plant seeds are most suitable organs to recruit these microbes to get maximum symbiotic benefits. Seed-inhabiting endophytes, both bacteria and fungi, are believed to be closer and more compatible to plants. Plant recruits these persistent endophytes into their seeds, and they may be transmitted vertically from generation to generation. Seed-inhabiting endophytes benefits host plant in terms of growth promotion, improving fitness, providing protection against diseases starting from germination stage to seedling establishment, and also improving reproductive fitness of plant. Moreover, seed endophytes enter inside the plant body and stimulate expressions of growth and genes related to abiotic stress and defense. In this chapter, we discuss the ecology of seed-inhabiting bacterial and fungal endophytes and their various functional roles during seedling development. © 2021 Elsevier B.V. All rights reserved.