MICROBIOME OF RICE AS INFLUENCED BY CYANOBACTERIAL INOCULATION
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Date
2014
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Division of Microbiology Indian Agricultural Research Institute New Delhi
Abstract
Plants are full of microbes and phenotypic expression of most plants in nature is the
product of highly co-regulated expression of genes both from plants and microbes. The
present investigation was undertaken to analyse the effect of cyanobacterial inoculation
on the structure and function of microbial communities in soil and the rice microbiome,
using a combination of culturable and culture-independent approaches.
The cultural bacterial diversity of the rice plant microbiome (microbial
communities in roots and shoots) was investigated in the presence and absence of
cyanobacterial inoculation in rice seedlings, under controlled conditions in water agar
using rice cultivar cv. Pusa Sugandh 5 (Pusa 2511). Population densities ranging from
106
-109 CFU/ml of culturable microorganisms were recorded in the root and shoot
tissues in different types of nutrient media. Five and three isolates exhibited nitrogen
fixation and phosphorus solubilisation, respectively. Sixteen morphotypes were selected
for profiling of fatty acid methyl esters (FAME) and 16S rDNA sequencing, which
showed that about 50% of the isolates belonged to the Family Bacillaceae of the
Phylum Firmicutes. A significant enhancement in plant growth and physiological
attributes were recorded which was complemented by SEM observations revealing an
enhancement in rod-shaped cells in both root and shoot tissues of Calothrix inoculated
plants, along with the presence of short 2-3 celled filaments, presumably of Calothrix
sp.
In order to understand the interactions of soil and plant microbiome, with or
without cyanobacterial inoculation, a pot experiment, using sterile and unsterile soil was
carried out under the controlled conditions of the National Phytotron Facility, IARI,
New Delhi. Culture-independent, microbial community-based approaches such as
phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE)
profiling, complemented by evaluation of soil nutrient status and microbiological
parameters were employed. Principal component analysis of these PLFA profiles
showed that inoculation with Calothrix brought about distinct temporal changes in the
concentrations of individual PLFA(s) and microbial guilds. DGGE based studies
illustrated the significant role of cyanobacteria in modulating the microbiome of rice. It
can be concluded that positive effect of cyanobacterial inoculation on the rice plant
growth is probably due to its role in maintaining the “beneficial core microbiome of
rice."
Description
t-9021
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