Abiotic stressors, such as drought, flooding, extreme temperature, soil salinity, and metal toxicity, are the most important factors limiting crop productivity. Plants use their innate biological systems to overcome these abiotic stresses caused by environmental and edaphic conditions. Microorganisms that live in and around plant systems have incredible metabolic abilities in mitigating abiotic stress. Recent advances in multi-omics methods, such as metagenomics, genomics, transcriptomics, and proteomics, have helped to understand how plants interact with microbes and their environment. These methods aid in the construction of various metabolic models of microbes and plants, resulting in a better knowledge of all metabolic exchanges engaged during interactions. Actinobacteria are ubiquitous and are excellent candidates for plant growth promotion because of their prevalence in soil, the rhizosphere, their capacity to colonize plant roots and surfaces, and their ability to produce various secondary metabolites. Mechanisms by which actinobacteria overcome abiotic stress include the production of osmolytes, plant hormones, and enzymes, maintaining osmotic balance, and enhancing nutrient availability. With these characteristics, actinobacteria members are the most promising candidates as microbial inoculants. This review focuses on actinobacterial diversity in various plant regions as well as the impact of abiotic stress on plant-associated actinobacterial diversity and actinobacteria-mediated stress mitigation processes. The study discusses the role of multi-omics techniques in expanding plant–actinobacteria interactions, which aid plants in overcoming abiotic stresses and aims to encourage further investigations into what may be considered a relatively unexplored area of research.

Rice is a crucial crop for many people worldwide, especially in regions like Asia, Latin America, and parts of Africa. Thailand is one of the largest exporters of rice. Nowadays, farmers use chemicals to control rice disease, which can have negative effects on humans and the environment. Therefore, the objective of this study was to examine the plant-promoting capabilities of the endophytic fungal strains DMKU-R3G3 in greenhouse settings. The endophytic fungi strain DMKU-R3G3, which was isolated from organic rice root, was identified as Aspergillus cejpii based on morphological characteristics and phylogenetic analysis. The production of IAA was detected using Salkowski’s reagent. After 7 days of incubation, the finding revealed that the strain cultivated in PDB supplemented with tryptophan yielded a greater concentration of IAA (25.45 μg/mL). The inoculation with A. cejpii DMKU-R3G3 significantly enhanced rice growth, as evidenced by notable increases in shoot height, root length, and fresh weight. Moreover, the chlorophyll content of the rice plants also increased by 1.78 times more than the control group. In addition, proteomic analysis revealed that rice responded toward the colonization of endophytic fungi by producing auxin-responsive proteins to regulate the IAA content in plant tissue and inducing total chlorophyll production due to the up-regulation of proteins in the chlorophyll biosynthesis pathway. The results obtained from this study lead to the conclusion that the A. cejpii strain DMKU-R3G3 possesses the capability to enhance plant growth through the production of phytohormones in greenhouse conditions. Therefore, endophytic A. cejpii DMKU-R3G3 has the potential to be a promising eco-friendly plant growth promoter for sustainable rice cultivation.

Sugarcane white leaf (SCWL) disease, caused by Candidatus Phytoplasma sacchari, results in the most damage to sugarcane plantations. Some SCWL canes can grow unnoticed through the maturation phase, subsequently resulting in an overall low sugar yield, or they can be used accidentally as seed canes. In this work, 12-month-old SCWL and asymptomatic canes growing in the same field were investigated. An abundance of phytoplasma in SCWL canes affected growth and sugar content as well as alterations of transcriptomic profiles corresponding to several pathways that responded to the infection. Suppression of photosynthesis, porphyrin and chlorophyll metabolism, coupled with an increase in the expression of chlorophyllase, contributed to the reduction in chlorophyll levels and photosynthesis. Blockage of sucrose transport plausibly occurred due to the expression of sugar transporters in leaves but suppression in stalks, resulting in low sugar content in canes. Increased expression of genes associated with MAPK cascades, plant hormone signaling transduction, callose plug formation, the phenylpropanoid pathway, and calcium cascades positively promoted defense mechanisms against phytoplasma colonization by an accumulation of lignin and calcium in response to plant immunity. Significant downregulation of CPK plausibly results in a reduction in antioxidant enzymes and likely facilitates pathogen invasion, while expression of sesquiterpene biosynthesis possibly attracts the insect vectors for transmission, thereby enabling the spread of phytoplasma. Moreover, downregulation of flavonoid biosynthesis potentially intensifies the symptoms of SCWL upon challenge by phytoplasma. These SCWL sugarcane transcriptomic profiles describe the first comprehensive sugarcane–phytoplasma interaction during the harvesting stage. Understanding molecular mechanisms will allow for sustainable management and the prevention of SCWL disease—a crucial benefit to the sugar industry.

Sugarcane white leaf (SCWL) disease, caused by Candidatus Phytoplasma sacchari, poses a significant threat to sugarcane cultivation. An obligate parasite, phytoplasma is difficult to culture in laboratory conditions, making the isolation of its DNA from the massive amount of plant host DNA extremely challenging. Yet, the appropriate amount and quality of plant microbiome-derived DNA are key for high-quality DNA sequencing data. Here, a simple, cost-effective, alternative method for DNA isolation was applied using a guanidine-HCl-hydroxylated silica (GuHCl-Silica)-based method and microbiome DNA enrichment based on size-selective low-molecular-weight (LMW) DNA by PEG/NaCl precipitation. qPCR analysis revealed a significant enrichment of phytoplasma DNA in the LMW fraction. Additionally, the NEBNext Microbiome DNA enrichment kit was utilized to further enrich microbial DNA, demonstrating a remarkable increase in the relative abundance of phytoplasma DNA to host DNA. Shotgun sequencing of the isolated DNA gave high-quality data on the metagenome assembly genome (MAG) of Ca. Phytoplasma sacchari SCWL with completeness at 95.85 and 215× coverage. The results indicate that this combined approach of PEG/NaCl size selection and microbiome enrichment is effective for obtaining high-quality genomic data from phytoplasma, surpassing previous methods in efficiency and resource utilization. This low-cost method not only enhances the recovery of microbiome DNA from plant hosts but also provides a robust framework for studying plant pathogens in complex plant models.

Seed germination is a critical phase in rice production and is highly sensitive to environmental and chemical stresses. Chloramphenicol (CAM), a known phytotoxic antibiotic, has been reported to suppress rice seedling establishment, yet its underlying molecular mechanisms remain poorly understood. In this study, we investigated the effects of varying CAM concentrations on rice germination and early seedling establishment. While CAM significantly retarded germination speed and seedling growth, the final germination rates remained largely unaffected, even at high concentrations. To uncover the molecular basis of CAM phytotoxicity, we conducted time-resolved phosphoproteomic profiling during both the germination and early seedling stages. Our analyses revealed dynamic, stage-specific phosphorylation changes: moderate alterations affecting metabolic and cytokinesis-related processes during germination, and extensive disruptions in metabolic pathways, stress response mechanisms, DNA replication, and hormone signaling during early seedling establishment. Collectively, these findings demonstrate that CAM disrupts rice development by remodeling phosphorylation networks and modulating key physiological and signaling pathways. This study provides novel insights into the molecular mechanisms underlying antibiotic-induced growth inhibition and advances our understanding of plant stress responses during early development.