Comparative Analysis of Various Strains of Plant Growth Promoting Rhizobacteria on the Physiology of Garlic (Allium sativum)

Garlic is a most important medicinal herb belonging to the family Liliaceae. Both its leaves and bulb are edible. The current study was based on evaluating the growth promoting potential of plant growth promoting rhizobacteria (PGPR) on garlic (Allium sativum L.) growth and biochemical contents. Garlic cloves were inoculated with 3 kinds of PGPRs, Pseudomonas putida (KX574857), Pseudomonas stutzeri (Kx574858) and Bacillus cereus (ATCC14579) at 108 cells/mL prior to sowing. Under natural conditions, plants were grown in the net house. The PGPR significantly enhanced % germination, leaf and root growth and their biomass also increased the diameter of bulb and fresh and dry weight. The flavonoids, phenolics, chlorophyll, protein and sugar content were also significantly increased due to PGPR inoculation. The Pseudomonas stutzeri was found most effective for producing longer leaves with moderate sugar, high flavonoids (129%) and phenolics (263%) in bulb over control (Tap). The Pseudomonas putida exhibited a maximum increase in bulb diameter and bulb biomass with maximum phenolics and flavonoid contents.

Implications of carbon catabolite repression for plant–microbe interactions

Carbon catabolite repression(CCR)plays a key role in many physiological and adaptive responses in a broad range of microorganisms that are commonly associated with eukaryotic hosts.When a mixture of different carbon sources is available,CCR,a global regulatory mechanism,inhibits the expression and activity of cellular processes associated with utilization of secondary carbon sources in the presence of the preferred carbon source.CCR is known to be executed by completely different mechanisms in different bacteria,yeast,and fungi.In addition to regulating catabolic genes,CCR also appears to play a key role in the expression of genes involved in plant–microbe interactions.Here,we present a detailed overview of CCR mechanisms in various bacteria.We highlight the role of CCR in beneficial as well as deleterious plant–microbe interactions based on the available literature.In addition,we explore the global distribution of known regulatory mechanisms within bacterial genomes retrieved from public repositories and within metatranscriptomes obtained from different plant rhizospheres.By integrating the available literature and performing targeted meta-analyses,we argue that CCR-regulated substrate use preferences of microorganisms should be considered an important trait involved in prevailing plant–microbe interactions.

Phyllosphere microbiota:Community dynamics and its interaction with plant hosts

Plants are colonized by various microorganisms in natural environments.While many studies have demonstrated key roles of the rhizosphere microbiota in regulating biological processes such as nutrient acquisition and resistance against abiotic and biotic challenges,less is known about the role of the phyllosphere microbiota and how it is established and maintained.This review provides an update on current understanding of phyllosphere community assembly and the mechanisms by which plants and microbes establish the phyllosphere microbiota for plant health.

Active DNA demethylation in plants:20 years of discovery and beyond

Maintaining proper DNA methylation levels in the genome requires active demethylation of DNA.However,removing the methyl group from a modified cytosine is chemically difficult and therefore,the underlying mechanism of demethylation had remained unclear for many years.The discovery of the first eukaryotic DNA demethylase,Arabidopsis thaliana REPRESSOR OF SILENCING 1(ROS1),led to elucidation of the 5-methylcytosine base excision repair mechanism of active DNA demethylation.In the 20 years since ROS1 was discovered,our understanding of this active DNA demethylation pathway,as well as its regulation and biological functions in plants,has greatly expanded.These exciting developments have laid the groundwork for further dissecting the regulatory mechanisms of active DNA demethylation,with potential applications in epigenome editing to facilitate crop breeding and gene therapy.