4 research outputs found
Decoding seasonal changes: soil parameters and microbial communities in tropical dry deciduous forests
In dry deciduous tropical forests, both seasons (winter and summer) offer habitats that are essential ecologically. How these seasonal changes affect soil properties and microbial communities is not yet fully understood. This study aimed to investigate the influence of seasonal fluctuations on soil characteristics and microbial populations. The soil moisture content dramatically increases in the summer. However, the soil pH only gradually shifts from acidic to slightly neutral. During the summer, electrical conductivity (EC) values range from 0.62 to 1.03 ds m-1, in contrast to their decline in the winter. The levels of soil macronutrients and micronutrients increase during the summer, as does the quantity of soil organic carbon (SOC). A two-way ANOVA analysis reveals limited impacts of seasonal fluctuations and specific geographic locations on the amounts of accessible nitrogen (N) and phosphorus (P). Moreover, dehydrogenase, nitrate reductase, and urease activities rise in the summer, while chitinase, protease, and acid phosphatase activities are more pronounced in the winter. The soil microbes were identified in both seasons through 16S rRNA and ITS (Internal Transcribed Spacer) gene sequencing. Results revealed Proteobacteria and Ascomycota as predominant bacterial and fungal phyla. However, Bacillus, Pseudomonas, and Burkholderia are dominant bacterial genera, and Aspergillus, Alternaria, and Trichoderma are dominant fungal genera in the forest soil samples. Dominant bacterial and fungal genera may play a role in essential ecosystem services such as soil health management and nutrient cycling. In both seasons, clear relationships exist between soil properties, including pH, moisture, iron (Fe), zinc (Zn), and microbial diversity. Enzymatic activities and microbial shift relate positively with soil parameters. This study highlights robust soil-microbial interactions that persist mainly in the top layers of tropical dry deciduous forests in the summer and winter seasons. It provides insights into the responses of soil-microbial communities to seasonal changes, advancing our understanding of ecosystem dynamics and biodiversity preservation
High-Throughput Sequencing-Based Analysis of Rhizosphere and Diazotrophic Bacterial Diversity Among Wild Progenitor and Closely Related Species of Sugarcane (Saccharum spp. Inter-Specific Hybrids)
Considering the significant role of genetic background in plant-microbe interactions and
that most crop rhizospheric microbial research was focused on cultivars, understanding
the diversity of root-associated microbiomes in wild progenitors and closely related
crossable species may help to breed better cultivars. This study is aimed to fill a critical
knowledge gap on rhizosphere and diazotroph bacterial diversity in the wild progenitors
of sugarcane, the essential sugar and the second largest bioenergy crop globally. Using a
high-throughput sequencing (HTS) platform, we studied the rhizosphere and diazotroph
bacterial community of SaccharumofficinarumL. cv. Badila (BRS), Saccharumbarberi (S.
barberi) Jesw. cv Pansahi (PRS), Saccharum robustum [S. robustum; (RRS), Saccharum
spontaneum (S. spontaneum); SRS], and Saccharum sinense (S. sinense) Roxb. cv Uba
(URS) by sequencing their 16S rRNA and nifH genes. HTS results revealed that a total
of 6,202 bacteria-specific operational taxonomic units (OTUs) were identified, that were
distributed as 107 bacterial groups. Out of that, 31 rhizobacterial families are commonly
spread in all five species. With respect to nifH gene, S. barberi and S. spontaneum
recorded the highest and lowest number of OTUs, respectively. These results were
validated by quantitative PCR analysis of both genes. A total of 1,099 OTUs were identified for diazotrophs with a core microbiome of 9 families distributed among all the
sugarcane species. The core microbiomes were spread across 20 genera. The increased
microbial diversity in the rhizosphere was mainly due to soil physiochemical properties.
Most of the genera of rhizobacteria and diazotrophs showed a positive correlation,
and few genera negatively correlated with the soil properties. The results showed
that sizeable rhizospheric diversity exists across progenitors and close relatives. Still,
incidentally, the rhizosphere microbial abundance of progenitors of modern sugarcane
was at the lower end of the spectrum, indicating the prospect of Saccharum species
introgression breeding may further improve nutrient use and disease and stress tolerance
of commercial sugarcane. The considerable variation for rhizosphere microbiome seen
in Saccharum species also provides a knowledge base and an experimental system for
studying the evolution of rhizobacteria-host plant association during crop domestication
Sugarcane Root Transcriptome Analysis Revealed the Role of Plant Hormones in the Colonization of an Endophytic Diazotroph
Some sugarcane germplasms can absorb higher amounts of nitrogen via atmospheric
nitrogen fixation through the bacterial diazotrophs. Most endophytic diazotrophs usually
penetrate through the root, colonize inside the plant, and fix the nitrogen. To assess
the plant’s bacterial association during root colonization, strain GXS16 was tagged with
a plasmid-bear green fluorescent protein (GFP) gene. The results demonstrated that
the strain can colonize roots all the way to the maturation zone. The strain GXS16
showed maximum nitrogenase enzyme activity at pH 8 and 30 C, and nitrogenase
activity is less affected by different carbon sources. Further, strain GXS16 colonization
response was investigated through plant hormones analysis and RNAseq. The results
showed that the bacterial colonization gradually increased with time, and the H2O2 and
malondialdehyde (MDA) content significantly increased at 1 day after inoculation. There
were no substantial changes noticed in proline content, and the ethylene content was
detected initially, but it decreased with time. The abscisic acid (ABA) content showed
significant increases of 91.9, 43.9, and 18.7%, but conversely, the gibberellin (GA3)
content decreased by 12.9, 28.5, and 45.2% at 1, 3, and 5 days after inoculation,
respectively. The GXS16 inoculation significantly increased the activities of catalase
(CAT), superoxide dismutase (SOD), polyphenol oxidase (PPO), ascorbate peroxidase
(APX), and glutathione reductase (GR) at different timepoint. In contrast, the peroxisome
(POD) activity had no changes detected during the treatment. In the case of RNAseq
analysis, 2437, 6678, and 4568 differentially expressed genes (DEGs) were identified
from 1, 3, and 5 days inoculated root samples, and 601 DEGs were shared in all
samples. The number or the expression diversity of DEGs related to ethylene was much
higher than that of ABA or GA, which indicated the critical role of ethylene in regulating
the sugarcane roots response to GXS16 inoculation
Table_1_Functional interplay between antagonistic bacteria and Rhizoctonia solani in the tomato plant rhizosphere.DOCX
Microbial interactions with plant roots play an imperial role in tomato plant growth and defense against the Rhizoctonia solani. This study performed a field experiment with two antagonistic bacteria (Pseudomonas and Bacillus) inoculated in healthy and Rhizoctonia solani treated soil in tomato rhizosphere to understand the metabolic pattern and microbial function during plant disease suppression. In the present study, we assessed soil and microbial enzymes, bacterial and fungal cell forming unit (CFU), and carbon utilization profiling through Bio-Eco plates of rhizoplane samples. Antagonist bacteria and pathogen interaction significantly (p < 0.05) influenced the bacterial count, soil enzymes (chitinase and glucanase), and bacterial function (siderophore and chitinase production). These results indicated that these variables had an imperial role in disease suppression during plant development. Furthermore, the metabolic profiling showed that carbon source utilization enhanced under fruit development and ripening stages. These results suggested that carbon sources were essential in plant/pathogen/antagonist interaction. Substrates like β-methyl-D-glucoside, D-mannitol, D-galacturonic acid, N-acetyl-D-glucosamine, and phenylethylamine strongly connect with the suppuration of root rot disease. These carbon sources may help to propagate a healthy microbial community to reduce the pathogen invasion in the plant root system, and these carbon sources can be stimulators of antagonists against pathogens in the future.</p