Exploring Functional Diversity and Community Structure of Diazotrophic Endophytic Bacteria Associated with Pennisetum glaucum Growing under Field in a Semi-Arid Region

Garima Gupta, Sangeeta Paul, Sachidanand Singh, Giacomo Pietramellara, Shamina Imran Pathan, Subhan Danish, Dilfuza Jabborova, Rahul Datta and Prabhat Nath Jha
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Garima Gupta: Institute of Bioscience and Technology, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Barabanki 225003, India
Sangeeta Paul: Indian Agricultural Research Institute, Pusa, New Delhi 110012, India
Sachidanand Singh: Department of Biotechnology, Vignan’s Foundation for Science, Technology and Research, Vadlamudi, Guntur 522213, India
Giacomo Pietramellara: Department of Agriculture, Food, Environment and Forestry, University of Florence, P.le delle Cascine 28, 50144 Firenze, Italy
Shamina Imran Pathan: Department of Agriculture, Food, Environment and Forestry, University of Florence, P.le delle Cascine 28, 50144 Firenze, Italy
Subhan Danish: Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou 570228, China
Dilfuza Jabborova: Institute of Genetics and Plant Experimental Biology, Uzbekistan Academy of Sciences, Kibray 111208, Uzbekistan
Rahul Datta: Department of Geology and Pedology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 1, 61300 Brno, Czech Republic
Prabhat Nath Jha: Centre for Biotechnology, Department of Biological Sciences, Birla Institute of Technology and Science, Pilani 333031, India

Land, 2022, vol. 11, issue 7, 1-24

Abstract: Diazotrophic endophytic bacteria (DEB) are the key drivers of nitrogen fixation in rainfed soil ecosystems and, hence, can influence the growth and yield of crop plants. Therefore, the present work investigated the structure and composition of the DEB community at different growth stages of field-grown pearl millet plants, employing the cultivation-dependent method. Diazotrophy of the bacterial isolates was confirmed by acetylene reduction assay and amplification of the nifH gene. ERIC-PCR-based DNA fingerprinting, followed by 16S rRNA gene analysis of isolates recovered at different time intervals, demonstrated the highest bacterial diversity during early (up to 28 DAS (Days after sowing)) and late (63 DAS onwards) stages, as compared to the vegetative growth stage (28–56 DAS). Among all species, Pseudomonas aeruginosa was the most dominant endophyte. Assuming modulation of the immune response as one of the tactics for successful colonization of P. aeruginosa PM389, we studied the expression of the profile of defense genes of wheat, used as a host plant, in response to P. aeruginosa inoculation. Most of the pathogenesis-related PR genes were induced initially (at 6 h after infection (HAI)), followed by their downregulation at 12 HAI. The trend of bacterial colonization was quantified by qPCR of 16S rRNAs. The results obtained in the present study indicated an attenuated defense response in host plants towards endophytic bacteria, which is an important feature that helps endophytes establish themselves inside the endosphere of roots.

Keywords: ERIC; nitrogen fixation; pearl millet; qPCR; PM389; PR genes; Pseudomonas aeruginosa (search for similar items in EconPapers)
JEL-codes: Q15 Q2 Q24 Q28 Q5 R14 R52 (search for similar items in EconPapers)
Date: 2022
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