Development of Mesorhizobium ciceri-Based Biofilms and Analyses of Their Antifungal and Plant Growth Promoting Activity in Chickpea Challenged by Fusarium Wilt

Abstract

Biofilmed biofertilizers have emerged as a new improved inoculant technology to provide efficient nutrient and pest management and sustain soil fertility. In this investigation, development of a Trichoderma viride-Mesorhizobium ciceri biofilmed inoculant was undertaken, which we hypothesized, would possess more effective biological nitrogen fixing ability and plant growth promoting properties. As a novel attempt, we selected Mesorhizobium ciceri spp. with good antifungal attributes with the assumption that such inoculants could also serve as biocontrol agents. These biofilms exhibited significant enhancement in several plant growth promoting attributes, including 13-21 % increase in seed germination, production of ammonia, IAA and more than onefold to twofold enhancement in phosphate solubilisation, when compared to their individual partners. Enhancement of 10-11 % in antifungal activity against Fusarium oxysporum f. sp. ciceri was also recorded, over the respective M. ciceri counterparts. The effect of biofilms and the M. ciceri cultures individual on growth parameters of chickpea under pathogen challenged soil illustrated that the biofilms performed at par with the M. ciceri strains for most plant biometrical and disease related attributes. Elicitation of defense related enzymes like L-phenylalanine ammonia lyase, peroxidase and polyphenol oxidase was higher in M. ciceri/biofilm treated plants as compared to uninoculated plants under pathogen challenged soil. Further work on the signalling mechanisms among the partners and their tripartite interactions with host plant is envisaged in future studies.

Beyond Risk: Bacterial Biofilms and Their Regulating Approaches

“…For example, priming the seeds with phenazine-producing Pseudomonas chlororaphis can provide protection of barley and oats against seed borne diseases (Chin-A- Woeng et al, 2003); Pseudomonas putida 06909 attaches and colonizes the hyphae of citrus root rotting fungus Phytophthora parasitica by feeding on its exudates and then develop a biofilm around the citrus roots, which prevents further proliferation of the fungus (Steddom et al, 2002;Pandin et al, 2017); and Peanut rhizosphere biofilm formation by Paenibacillus polymyxa provides protection of peanut plants against crown root rot disease caused by Aspergillus niger (Haggag and Timmusk, 2008). Rhizhosphere colonization of beneficial biofilms usually offer excellent plant growth promotion and protection against phytopathogens (Das et al, 2017).…”

Biofertilizers: An ecofriendly technology for nutrient recycling and environmental sustainability

“…Lactose contains eight hydroxyl groups, which protects the bacterial cell, during storage, from free radicals ( Zárate et al, 2005 ). Another fascinating technique, which is proved to be efficient is the biofilm-based biofertilizers ( Das et al, 2017 ). Currently, PGPRs are immobilised on a fungal matrix for biofilm formation.…”

Agriculturally important microbial biofilms: Present status and future prospects

“…EPS provide a strategic environment for plant pathogens to survive inside the host plant, by acting as a barrier against plant defense systems . Several genera of agriculturally important bacteria, fungi, cyanobacteria including Agrobacterium , Anabaena , Azospirillum , Azotobacter , Bacillus , Bradyrhizobium , Burkholderia , Clavibacter , Erwinia , Gluconacetobacter , Herbaspirillum , Mesorhizobium , Paenibacillus , Pantoea , Pseudomonas , Ralstonia , Rhizobium , Sinorhizobium , Trichoderma , Xanthomonas , Xylella are reported to produce single or multispecies biofilms (Table ).…”