Molecular dynamics in germinating, endophyte-colonized quinoa seeds

Colonization of Raphanus sativus by human pathogenic microorganisms

Contamination of vegetables with human pathogenic microorganisms (HPMOs) is considered one of the most important problems in the food industry, as current nutritional guidelines include increased consumption of raw or minimally processed organic vegetables due to healthy lifestyle promotion. Vegetables are known to be potential vehicles for HPMOs and sources of disease outbreaks. In this study, we tested the susceptibility of radish (Raphanus sativus) to colonization by different HPMOs, including Escherichia coli PCM 2561, Salmonella enterica subsp. enterica PCM 2565, Listeria monocytogenes PCM 2191 and Bacillus cereus PCM 1948. We hypothesized that host plant roots containing bactericidal compounds are less prone to HPMO colonization than shoots and leaves. We also determined the effect of selected pathogens on radish growth to check host plant-microbe interactions. We found that one-week-old radish is susceptible to colonization by selected HPMOs, as the presence of the tested HPMOs was demonstrated in all organs of R. sativus. The differences were noticed 2 weeks after inoculation because B. cereus was most abundant in roots (log10 CFU - 2.54), S. enterica was observed exclusively in stems (log10 CFU - 3.15), and L. monocytogenes and E. coli were most abundant in leaves (log10 CFU - 4.80 and 3.23, respectively). The results suggest that E. coli and L. monocytogenes show a higher ability to colonize and move across the plant than B. cereus and S. enterica. Based on fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) approach HPMOs were detected in extracellular matrix and in some individual cells of all analyzed organs. The presence of pathogens adversely affected the growth parameters of one-week-old R. sativus, especially leaf and stem fresh weight (decreased by 47-66 and 17-57%, respectively). In two-week-old plants, no reduction in plant biomass development was noted. This observation may result from plant adaptation to biotic stress caused by the presence of HPMOs, but confirmation of this assumption is needed. Among the investigated HPMOs, L. monocytogenes turned out to be the pathogen that most intensively colonized the aboveground part of R. sativus and at the same time negatively affected the largest number of radish growth parameters.

Endophytic Bacillus sp. AP10 harboured in Arabis paniculata mediates plant growth promotion and manganese detoxification

Phytoremediation of heavy metal-polluted soils assisted by plant-associated endophytes, is a suitable method for plant growth and manganese (Mn) removal in contaminated soils. This investigation was conducted to evaluate the Mn-resistant endophytic resources of the Mn hyperaccumulator Arabis paniculata and their functions in the phytoremediation of Mn²⁺ toxicity. This study isolated an endophytic bacterium with high Mn resistance and indole-3-acetic acid (IAA) production form A. paniculata and identified it as Bacillus sp. AP10 using 16 S rRNA gene sequencing analysis. The effects of Bacillus sp. AP10 on the alleviation of Mn²⁺ toxicity in Arabidopsis thaliana seedlings and the molecular mechanisms were further investigated using biochemical tests and RNA-seq analysis. Under Mn²⁺ stress, Bacillus sp. AP10 increased the biomass, chlorophyll content and the translocation factor (TF) values of Mn in the aerial parts, while decreased the malondialdehyde (MDA) content of A. thaliana seedlings compared with that of control plants. The differentially expressed genes (DEGs) and enrichment analysis showed that Bacillus sp. AP10 could significantly increase the expression of key genes involved in cell-wall loosening, which may improve plant growth under Mn stress. Superoxide dismutase (SOD)-encoding genes were detected as DEGs after AP10 treatment. Moreover, AP10 regulated the expression of genes responsible for phenylpropanoid pathway, which may promote antioxidant flavonoids accumulation for reactive oxygen species (ROS) scavenging to improve Mn tolerance. The activation of ATP-binding cassette (ABC) transporter gene expression especially ABCB1 after AP10 stimulation, explained the elevation of metal ion binding or transport related to enhanced Mn accumulation in plants. Futhermore, AP10 might alleviate Mn toxicity through enhancing abscisic acid (ABA) responsive gene expression and ABA biosynthesis. These findings provide new insights into the functions and regulatory mechanism of Bacillus sp. AP10 in promoting plant growth, and tolerance, improving Mn accumulation and alleviating Mn²⁺ toxicity in plants. The application of Bacillus sp. AP10 as potential phytoremediators may be a promising strategy in Mn²⁺ contaminated fields. AVAILABILITY OF DATA AND MATERIALS: The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Exploring the potential of endophytes and their metabolites for bio-control activity

In the current scenario, extensive use of synthetic chemicals in agriculture is creating notable problems such as disease and pest resistance, residues, yield loss, and soil unproductiveness. These harmful chemicals are eventually reaching our food plate through bioaccumulation and biomagnification in a crop. As a result, beneficial microorganisms are regularly being explored as a safer option in the agriculture sector for their ability to produce valuable bioactive secondary metabolites, particularly for crop protection. Such natural (bio) products are harmless to plants, humans, and the environment. In our quest for the search of the sources of bioactive constituents from the microorganisms, endophytes are the front-runner. They mutually reside inside the plant providing support against phytopathogens by releasing an array of bioactive secondary metabolites building climate reliance of the host plant. The purpose of this review is to examine the biocontrol potential of endophytes against bacterial and fungal pathogens in sustainable agriculture. We also attempt to explain the structure and activity of the secondary metabolites produced by bacterial and fungal endophytes in conjunction with their biocontrol function. Additionally, we address potential future research directions for endophytes as biopesticides.

Diversity of cultivable microorganisms associated with Quinoa (Chenopodium quinoa) and their potential for plant growth-promotion

Quinoa (Chenopodium quinoa) has grown since ancestral times in the Andean mountains and Altiplano, which are the center of origin of this pseudo-cereal. The interaction of Quinoa with native microorganisms may have contributed to the success of this plant in very adverse climatic and soil conditions. This study addressed the microbial diversity associated with Quinoa plants growing in traditional lands. We employed a cultivable-dependent approach to characterize the communities and identify bacterial strains with potential application in agriculture. We identified bacterial isolates belonging to phyla Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria. The genera Bacillus and Rhizobium/Agrobacterium were the predominant groups in the Quinoa bacterial communities, while various Trichoderma species were also found in the fungi group. The plant growth-promoting ability of selected bacterial strains was assessed by culturing them on media and the in planta test. We used different assays to test the capabilities of the isolates for nitrogen fixation, phosphorus solubilization, and production of the phytohormone indole-3-acetic acid. We inoculated Quinoa seeds with some Bacillus strains and then evaluated plant growth and grain production. Plants inoculated with bacterial strains usually show increased growth parameters and grain yield. Altogether, this work reveals that Quinoa harbors many diverse cultivable bacteria and fungi, which could be used as biological amendments to promote plant growth in a chemical-free way. Avoiding chemical fertilizers helps reduce environmental pollution and maintains the organic character of Quinoa production. International Quinoa markets highly appreciate the organic quality of Quinoa. Keywords. Plant growth-promoting bacteria, Microbial diversity, Rhizosphere bacteria, Andean Altiplano, Trichoderma

Assembly and potential transmission of the lens culinaris seed microbiome

Soil is an important source of bacteria and fungi for the plant, but seeds can also provide microbial inocula through heritable or stochastic assembly. Seed-associated microbial communities can potentially interact with the host plant through multiple generations. Here, we assessed the impact of two different soil types on the seed microbiome assembly of seven lentil (Lens culinaris) genotypes under environmentally controlled conditions and examined the vertical transmission of bacterial communities from seed to seed across two generations. Bulk soil microbiomes and seed microbiomes were characterized using high-throughput amplicon sequencing of the bacterial 16S rRNA gene. Our results revealed that bacterial communities in the two soils differed significantly and that bacterial communities associated with seeds were significantly impacted by genotype (15%) in one of the soils. Co-occurrence of amplicon sequence variants (ASVs) between generations suggests members of the genera Cutibacterium, Methylobacterium, Sphingomonas, Streptococcus, and Tepidimonas are transmitted and preserved in lentil genotypes irrespective of the soil in which they were grown. Increasing our knowledge of how microbial communities carried by seeds are assembled, transmitted, and preserved offers a promising way for future breeding programs to consider microbial communities when selecting for more resilient and productive cultivars.

The effect of plant domestication on host control of the microbiota

Macroorganisms are colonized by microbial communities that exert important biological and ecological functions, the composition of which is subject to host control and has therefore been described as "an ecosystem on a leash". However, domesticated organisms such as crop plants are subject to both artificial selection and natural selection exerted by the agricultural ecosystem. Here, we propose a framework for understanding how host control of the microbiota is influenced by domestication, in which a double leash acts from domesticator to host and host to microbes. We discuss how this framework applies to a plant compartment that has demonstrated remarkable phenotypic changes during domestication: the seed.

Quinoa Abiotic Stress Responses: A Review

Quinoa (Chenopodium quinoa Willd.) is a genetically diverse Andean crop that has earned special attention worldwide due to its nutritional and health benefits and its ability to adapt to contrasting environments, including nutrient-poor and saline soils and drought stressed marginal agroecosystems. Drought and salinity are the abiotic stresses most studied in quinoa; however, studies of other important stress factors, such as heat, cold, heavy metals, and UV-B light irradiance, are severely limited. In the last few decades, the incidence of abiotic stress has been accentuated by the increase in unpredictable weather patterns. Furthermore, stresses habitually occur as combinations of two or more. The goals of this review are to: (1) provide an in-depth description of the existing knowledge of quinoa's tolerance to different abiotic stressors; (2) summarize quinoa's physiological responses to these stressors; and (3) describe novel advances in molecular tools that can aid our understanding of the mechanisms underlying quinoa's abiotic stress tolerance.