EVALUATION OF PERFORMANCE OF PLANT GROWTH PROMOTING BACTERIA (PGPB) CONTAINING 1-AMINOCYCLOPROPANE- 1-CARBOXYLATE DEAMINASE (ACCD) IN IMPROVING GROWTH AND YIELD OF CEREAL CROPS UNDER SALINITY STRESS
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Date
2017
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DEPARTMENT OF INDUSTRIAL MICROBIOLOGY JACOB INSTITUTE OF BIOTECHNOLOGY AND BIOENGINEERING SAM HIGGINBOTTOM UNIVERSITY OF AGRICULTURE, TECHNOLOGY AND SCIENCES ALLAHABAD 2017
Abstract
Soil salinity is an important problem for crop production in many parts of the world, especially in irrigated fields of arid and semiarid regions. Plant growth promoting bacteria (PGPB) are known to reduce adverse effect of environmental stress and thereby enhance the growth and development of plant health, soil fertility and agricultural sustainability. PGPB contain enzyme 1-aminocyclopropane-1-carboxylate deaminase (ACCD) that inhibits the ethylene production from its precursor ACC into α-ketobutyrate and ammonia. Removal of ACC significantly increases plant root and shoot length and protect the plant from stress. In the present study, 650 bacterial cultures were isolated from the soil of Model Organic Farm (SMOF) of Sam Higginbottom University of Agriculture, Technology and Sciences (SHUATS), Allahabad, India. Rich bacterial diversity in soil from SMOF both in terms of their types and functional plant growth promoting (PGP) traits was observed and represented by heterotrophs, coliforms, Pseudomonas spp., Azotobacter spp. and Rhizobium spp. and majority of them displayed multiple plant growth promoting (MPGP) traits. Bacterial isolates were predominately positive to production of ammonia (NH3) (93.2%), indole acetic acid (IAA) (89.6%), catalase (85.0%), 1-aminocyclopropane- 1-carboxylate deaminase (ACCD) (78.6%) and siderophore (69.0%). Richness of their functional characteristics is further revealed by their tolerance to salinity and wide range of pH. In the present study all isolates from organic farm were tolerant to > 5 % NaCl and wide range of pH. We obtained major (96-97%) constituent of bacterial population of nitrogen fixers Azotobacter spp. and Rhizobium spp. with multiple PGP traits and tolerance to salinity and wide range of pH. Twenty nine (29) potential PGPB were identified on the basis of molecular with 16S rRNA and sequences were submitted to NCBI and got different accession no. Also the potential PGPB were tolerant to high levels of trace elements, and resistant to multiple antibiotics. On the basis of tolerance to high salt (20%) concentration
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three salt tolerant PGPB (STPGPB) viz. E. cloacae (KP226569) (PR4), Enterobacter sp. (KP226570) (PR14) and A. nigricans (KP966496) (PR19) were selected for detailed studies. All the three STPGPB expressed significant increase (p<0.001) antioxidant enzymes activities (SOD, CAT and GSH) under the abiotic stress of salinity and pH. Inoculation with STPGPB exhibited higher percentage of seed germination and enhanced growth parameters in cereals seed such as rice, maize and millets under salinity stress. Further significantly (p<0.001) increased percentage of seed germination and enhanced growth of these cereals was noted under salinity in presence of ammonium sulfate (substitute of ACC) clearly demonstrating the role of ACCD in alleviation of abiotic stress, especially salinity.
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Ph.d thesis
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