Isolation, molecular characterization and growth-promoting activities of endophytic sugarcane diazotroph Klebsiella sp. GR9 |
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Authors: | Munusamy Govindarajan Soon-Wo Kwon Hang-Yeon Weon |
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Institution: | (1) Postgraduate and Research Department of Microbiology and Botany, AVVM Sri Pushpam College (Bharathidasan University, Trichy), Tanjore, 613503, Tamilnadu, India;(2) Genetic Resources Division, National Institute of Agricultural Biotechnology, Rural Development Administration 225th, Seodun-dong, Gwonseon-gu, Suwon, 441-707, Republic of Korea;(3) Applied Microbiology Division, National Institute of Agricultural Science and Technology, Rural Development Administration (RDA), Suwon, 441-707, Republic of Korea;(4) Present address: Dr. Rajan Laboratories, 28/6, Ganesh Flats, Thirumangai Mannan Street, Sundaram Colony, East Tambaram, Chennai, 600 059, Tamilnadu, India |
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Abstract: | A group of endophytic diazotrophs were isolated from surface-sterilized roots and stems of different sugarcane varieties in
the Tamilnadu region of India. From these, four isolates were selected, based on the highest acetylene reduction activity.
Gene-specific PCR amplification confirmed the presence of nif-D genes in those isolates. The 16S rRNA sequence of isolates GR4 and GR7 had a 99.5% sequence similarity to the Pseudomonas sp. pDL01 (AF125317) and 16S rDNA sequence of isolate GR3 had a 100% similarity to that of Burkholderia vietnamiensis (AY973820). The 16S rDNA sequence of isolate GR9 was 99.79% similar to that of the Klebsiella pneumoniae type strain (KPY17657). Colonization by the isolates was confirmed using micropropagated sugarcane and sterile rice seedlings.
Isolate GR9, identified as Klebsiella pneumoniae, was consistently more active in reducing acetylene as compared with the other isolates. The effects of GR9 and the sugarcane
diazotroph Gluconacetobacter diazotrophicus were compared in inoculated micropropagated sugarcane plantlets. The effects of K. pneumoniae GR9, and four other diazotrophs, G. diazotrophicus, Herbaspirillum seropedicae, Azospirillum lipoferum 4B, and Burkholderia vietnamiensis in inoculated rice seedlings were compared. GR9 alone or in combination with the other diazotrophs performed best under pot
conditions. The combined effects of nitrogen fixation and endophytic colonization of this diazotroph may be useful for the
development of bio-inoculants. |
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Keywords: | Sugarcane endophytic diazotrophs AR activity IAA production nifD gene amplification 16S rDNA sequences Inoculation |
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