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Plants play a key role for ecosystems and for life on the planet. Despite being sessile organisms, they face the different challenges that their environment offers them. One of these strategies has been the development of interactions with the microorganisms that surround them, thus achieving unique and beneficial relationships for both. However, despite the importance of these microbial communities for the health of plants, the ecosystems where they inhabit, and in general, for life on Earth, little is known about them. Currently, researchers have focused their attention in their study to understand their relationships and functions, seeking to take advantage of them for the benefit of the human being and the care of the environment. For this, the new DNA sequencing tools, known as “New-Generation Sequencing” (NGS) techniques have been applied, which allow the generation of a large amount of data that helps researchers in the study of these microbial communities and in their interactions with plants. In this review, we will try to describe the importance of these communities, the interactions they have with the plants that they inhabit, the benefits they provide, and the different Next-Generation Sequencing techniques used for their study.

Bacteria can establish beneficial interactions with plants by acting as growth promoters and enhancing stress tolerance during plant interactions. Likewise, bacteria can develop multispecies communities where multiple interactions are possible. In this work, we assessed the physiological effects of three bacteria isolated from an arid environment (Bacillus niacini, Bacillus megaterium, and Moraxella osloensis) applied as single species or as a consortium on oregano (Origanum vulgare L.) plants. Moreover, we assessed the quorum-sensing (QS) signaling activity to determine the molecular communication between plant-growth-promoting bacteria. The plant inoculation with B. megaterium showed a positive effect on morphometric and physiologic parameters. However, no synergistic effects were observed when a bacterial consortium was inoculated. Likewise, activation of QS signaling in biofilm assays was observed only for interspecies interaction within the Bacillus genus, not for either interaction with M. osloensis. These results suggest a neutral or antagonistic interaction for interspecific bacterial biofilm establishment, as well as for the interaction with oregano plants when bacteria were inoculated in a consortium. In conclusion, we were able to determine that the bacterial interactions are not always positive or synergistic, but they also might be neutral or antagonistic.

Phytophthora capsici causes root and stem rot disease in Capsicum. However, molecular mechanisms underlying this pathosystem are little known. The use of elicitors as tools that trigger defense responses to biotic stresses to study molecular plant defense has increased. In this study, early defense induced in the susceptible cultivar C. chinense using three elicitors to assess its role during interaction with hemibiotrophic P. capsici. The response to infection by phenotypic analyses across the time during disease development in seedlings treated with elicitors was compared. Likewise; defense-gene expression were investigated by qRT-PCR. A total of five resistance genes were used as markers of signaling pathways mediated by jasmonate/ethylene (JA/ET) and salicylic acid (SA). Further, six R genes analogs (CcRGAS) related to oomycete-defense were employed. The results showed that elicitors MeJA and b-aminobutyric acid (BABA) slightly reduced disease symptoms. Moreover, MeJA or BABA treatments followed by challenge with P. capsici up-regulated the expression level of genes related to the JA/ET signaling pathway (CcLOX2, CcPDF1 and CcETR1). Furthermore, MeJA treatment followed by challenge triggered a significant induction of de CcRGAS and CcRPP13 expression within 24 h of inoculation. This suggests that in the early defense mechanisms against P. capsici JA signaling plays an important role.

Bemisia tabaci (Hemiptera: Aleyrodidae) (Gennadius, 1889), es un complejo de especies cripticas plaga de varios cultivos. En la ultima decada, se reporto el desplazamiento del grupo genetico nativo de America por la especie invasiva de Medio Oriente-Asia Menor 1 (MEAM1) que cambio el estado de su distribucion. El objetivo de este estudio fue la identificacion del grupo genetico de B. tabaci, basados en el fragmento del gen marcador citocromo oxidasa I mitocondrial (mtCOI), asi como, la deteccion de virus pertenecientes al grupo de los Begomovirus en B. tabaci mediante la amplificacion de la region intergenica (IR). La identificacion del grupo genetico se llevo a cabo con insectos adultos (n = 210), los cuales se alimentaron de cultivos de Solanaceas y Cucurbitaceas en 2016 y 2017. Se determino la presencia de Begomovirus confirmando su papel como vector viral. La reconstruccion filogenetica de B. tabaci de Baja California Sur basada en el gen mtCOI demostro que la poblacion estudiada formo un grupo monofiletico con miembros del grupo genetico de MEAM1. El analisis de parsimonia de mtCOI indico una divergencia genetica menor al valor de corte del 4% (rango de 0.0 a 1.69%) de la poblacion analizada con miembros previamente reportados del grupo genetico MEAM1. Se logro la deteccion de la region IR especifica para los Begomovirus. Con base a los resultados obtenidos se sugiere que B. tabaci en Solanaceas y Cucurbitaceas de BCS, una region agricola aislada, pertenecen al grupo genetico MEAM1. Este grupo genetico se caracteriza por llevar a cabo una transmision mas eficiente de los Begomovirus. La presencia de mosca blanca perteneciente al grupo genetico MEAM1 pudo haber sido por la introduccion de plantas portadoras de esta plaga provenientes de regiones distantes.

Bacteria can establish beneficial interactions with plants by acting as growth promoters and enhancing stress tolerance during plant interactions. Likewise, bacteria can develop multispecies communities where multiple interactions are possible. In this work, we assessed the physiological effects of three bacteria isolated from an arid environment (

The 16SrXIII group from phytoplasma bacteria were identified in salivary glands from Homalodisca liturata, which were collected in El Comitan on the Baja California peninsula in Mexico. We were able to positively identify 15 16S rRNA gene sequences with the corresponding signature sequence of ‘Candidatus Phytoplasma ’ (CAAGAYBATKATGTKTAGCYGGDCT) and in silico restriction fragment length polymorphism (RFLP) profiles (F value estimations) coupled with a phylogenetic analysis to confirm their relatedness to ‘Candidatus Phytoplasma hispanicum’ , which in turn belongs to the 16SrXIII group. A restriction analysis was carried out with AluI and EcoRI to confirm that the five sequences belongs to subgroup D. The rest of the sequences did not exhibit any known RFLP profile related to a subgroup reported in the 16SrXIII group.

The mRNA differential display technique was used to identify genes from Habanero pepper ( Capsicum chinense Jacq.) seedlings whose expression is modified systemically by infection with the oomycete Phytophthora capsici L. Experiments with different oligonucleotide primer combinations revealed that no single gene was synthesised de novo . Instead, the quantitative accumulation of multiple transcripts was found. From these transcripts, levels of a nitrate reductase ( Capsicum chinense nitrate reductase, CcNR), which has a high percentage of identity with other Solanaceae NRs, showed a consistent increase a few hours after inoculation (hai) with P. capsici . Reverse northern blotting revealed the existence of basal levels of CcNR transcripts in different adult tissues; however, systemic levels rose dramatically after spraying seedlings with salicylic acid (SA) and ethephon (ET) but not with methyl jasmonate (MeJa). Both P. capsici and defence phytohormones (DP) also modified NR enzymatic activity (nitrite:NAD + oxidoreductase; EC 1.7.1.1) with similar kinetics. Because the application of DP induced and activated the CcNR differentially, it is possible that the activity of CcNR is related to a specific host defence response.

As the study of coconut defense responses against pathogenic microorganisms is hampered by the absence of suitable model systems, we investigated if imbibition of coconut calli with chitosan could be used in vitro to simulate the molecular interactions that occur with pathogens. Our results showed that calli imbibition with 10 mg mL −1 chitosan caused the accumulation of hydrogen peroxide, and stimulated a β -1,3-glucanase activity with an Rf near 0.1. In addition, in-gel kinase assay and specific immunoblotting showed that a ∼46 kDa MAPK-like protein was activated shortly after elicitation, and remained in this state for at least 80 min. Chitosan addition also differentially modified the expression of some genes, whose DNA sequence showed high similarities to receptor-like kinases (RLKs), Verticillium -like protein, and mitochondrial alternate oxidase 1b. Addition of salicylic acid to the calli also modified transcript abundance for these genes, while methyl jasmonate did not seem to influence their expression, implying that they could be involved in defense responses. These results strongly suggest that elicitation of coconut tissues cultivated in vitro constitutes a suitable alternative to characterize both biochemical and molecular interactions that occur between the coconut palm and its associated pathogens.