Correction to: Bacterial microbiota dynamics of Cannabis sativa L. under biotic stress induced by Tetranychus urticae.

The microbiota associated with Cannabis sativa L. plays a crucial role in plant growth and health, although the mechanisms by which it is modulated in response to different types of stress during cultivation remains under investigation. In this study, the bacterial microbiota of both rhizospheric and bulk soil associated with a therapeutic C. sativa variety was characterized across three stages of the cultivation cycle (early vegetative, late vegetative, and late flowering), comparing healthy plants and those under stress induced by Tetranychus urticae. In addition to microbial profiling, plant physiological parameters were assessed, along with the analysis of cannabinoid and terpene profiles in floral tissues. Analyses of alpha diversity, community structure, discriminant taxa (LEfSe), and functional predictions (PICRUSt2) were performed using 16S rRNA gene sequencing data. The results revealed stress-associated shifts in the rhizospheric bacterial community, characterized by changes in the dominance of several genera across plant developmental stages, including a reduced representation of taxa commonly associated with plant growth promotion. Functional predictions further indicated that in control conditions the rhizosphere community exhibited higher metabolic activity, enriched in pathways related to replication, transcription and protein synthesis, whereas under stress, functions shifted toward resource recycling and metabolic flexibility. These findings suggest that biotic stress triggers a functional and structural reorganization of the soil bacterial microbiota, favoring more resilient yet less beneficial communities for plant development.This study provides novel evidence of the interaction between insect, plant, and microbiota, with both agronomic and biotechnological implications.

Uncertain climate change encourages the assembly of cassava varieties with multiple tolerances to both abiotic and biotic stress. The research aimed to evaluate the multiple tolerances of cassava germplasm to drought stress and red spider mite attacks. The research was held at Installation for Research and Assessment of Agricultural Technology of Muneng from February to December 2019 using a randomized block design nested in two environments with two replicates. The treatments consisted of 50 cassava accessions from the Indonesian Legumes and Tuber Crops Research Institute collection and two irrigation environments, i.e. a normal environment and a drought environment. Drought stress caused a decrease in plant height, tuber yield; on the other hand, increased red spider mite attack. Eight accessions have Stress Tolerance Index values reaching above 1.00, and two of them also have resistance to red spider mites. Accessions MLG 10361 and MLG 10362 had a high level of tolerance to drought stress as well as resistance to red spider mites so that both accessions may be used as a source of multiple resistance genes for biotic and abiotic stresses.

For real-time reverse transcription-PCR (qRT-PCR) in soybean, reference genes in different tissues, developmental stages, various cultivars, and under stress conditions have been suggested but their usefulness for research on soybean under various biotic stresses occurring in North-Central U.S. is not known. Here, we investigated the expression stabilities of ten previously recommended reference genes (ABCT, CYP, EF1A, FBOX, GPDH, RPL30, TUA4, TUB4, TUA5, and UNK2) in soybean under biotic stress from Bean pod mottle virus (BPMV), powdery mildew (PMD), soybean aphid (SBA), and two‐spotted spider mite (TSSM). BPMV, PMD, SBA, and TSSM are amongst the most common pest problems on soybean in North-Central U.S. and other regions. Reference gene stability was determined using three software algorithms (geNorm, NormFinder, BestKeeper) and a web-based tool (RefFinder). Reference genes showed variability in their expression as well as stability across various stressors and the best reference genes were stress-dependent. ABCT and FBOX were found to be the most stable in soybean under both BPMV and SBA stress but these genes had only minimal to moderate stability during PMD and TSSM stress. Expression of TUA4 and CYP was found to be most stable during PMD stress; TUB4 and TUA4 were stable under TSSM stress. Under various biotic stresses on soybean analyzed, GPDH expression was found to be consistently unstable. For all biotic stressors on soybean, we obtained pairwise variation (V2/3) values less than 0.15 which suggested that combined use of the two most stable reference genes would be sufficient for normalization. Further, we demonstrated the utility of normalizing the qRT-PCR data for target genes using the most stable reference genes validated in current study. Following of the recommendations from our current study will enable an accurate and reliable normalization of qRT-PCR data in soybean under biotic stress.

Biotic stress caused by Tetranychus urticae mites elevates the quantity of secondary metabolites, cannabinoids and terpenes, in Cannabis sativa L.

IntroductionThe two-spotted spider mite (TSSM) is a devastating pest of cassava production in China. Lignin is considered as an important defensive barrier against pests and diseases, several genes participate in lignin biosynthesis, however, how these genes modulate lignin accumulation in cassava and shape TSSM-resistance is largely unknown.MethodsTo fill this knowledge gap, while under TSSM infestation, the cassava lignin biosynthesis related genes were subjected to expression pattern analysis followed by family identification, and genes with significant induction were used for further function exploration.ResultsMost genes involved in lignin biosynthesis were up-regulated when the mite-resistant cassava cultivars were infested by TSSM, noticeably, the MePAL gene presented the most vigorous induction among these genes. Therefore, we paid more attention to dissect the function of MePAL gene during cassava-TSSM interaction. Gene family identification showed that there are 6 MePAL members identified in cassava genome, further phylogenetic analysis, gene duplication, cis-elements and conserved motif prediction speculated that these genes may probably contribute to biotic stress responses in cassava. The transcription profile of the 6 MePAL genes in TSSM-resistant cassava cultivar SC9 indicated a universal up-regulation pattern. To further elucidate the potential correlation between MePAL expression and TSSM-resistance, the most strongly induced gene MePAL6 were silenced using virus-induced gene silencing (VIGS) assay, we found that silencing of MePAL6 in SC9 not only simultaneously suppressed the expression of other lignin biosynthesis genes such as 4-coumarate--CoA ligase (4CL), hydroxycinnamoyltransferase (HCT) and cinnamoyl-CoA reductase (CCR), but also resulted in decrease of lignin content. Ultimately, the suppression of MePAL6 in SC9 can lead to significant deterioration of TSSM-resistance.DiscussionThis study accurately identified MePAL6 as critical genes in conferring cassava resistance to TSSM, which could be considered as promising marker gene for evaluating cassava resistance to insect pest.

Tea plants (Camellia sinensis L. (Kuntze)) face various biotic stresses as a result of attacks from different pests. Among them, red spider mite (Oligonychus coffeae, Nietner) has been a major challenge in recent years in India. This study assessed the effectiveness of biocontrol methods along with judicious use of synthetic acaricides on red spider mite populations in tea gardens in South India. The results demonstrated the importance of integrating different modules of biocontrol procedures by using a natural enemy (Mallada desjardinsi) of the red spider mite, a bacterium (Pseudomonas fluorescens), aqueous leaf extracts of Indian wormwood (Artemisia nilagirica), along with judicious use of acaricides for effective population reduction. These results can be considered as a first step towards the utilization of various biocontrol methods in the management of red spider mite infestation in tea as they can be used to improve the existing management strategy for this pest.

The effect of spider mite-pathogenic strains of Beauveria bassiana and humidity on the survival and feeding behavior of Neoseiulus predatory mite species

The two-spotted spider mite (TSSM) Tetranychus urticae is a polyphagous pest which infests several wild and cultivated species of plants worldwide. To date, this mite is the most deleterious pest attacking the strawberry plant under a protected environment. Exogenously applied salicylic acid (SA) has been found to induce resistance to biotic and abiotic stresses. Morpho-anatomical changes in strawberry leaflets and TSSM preference tests were investigated in response to SA treatment. Plants grown in a greenhouse were foliar sprayed with different concentrations of SA (0 mg · L−1, 25 mg · L−1, 50 mg · L−1, 75 mg · L−1 and 100 mg · L−1). After the third application, certain parameters including the number of glandular and non-glandular trichomes, thickness of leaflet, abaxial cell wall, adaxial cell wall, palisade and lacunous parenchyma and mesophyll were measured using scanning electronic microscopy (SEM). Two-choice and non-choice assays were employed to verify the TSSM preference. Exogenous treatment with SA promoted morpho-anatomical changes in the following parameters, namely: thickness of the leaflets, mesophyll, lacunous and palisade parenchyma, cell wall (abaxial and adaxial) and the number of glandular and non-glandular trichomes in strawberry leaflets. In general, TSSM preferred less leaflets treated with SA compared with the control in a two-choice assay. A lesser number of TSSM eggs and live females were also recorded in leaflets treated with SA compared with the control plants in no-choice assays. The values of the number of eggs and live females correlated negatively with those obtained for the morpho-anatomical traits induced by exogenous SA.

In spatio-temporal plant monitoring, optical sensing (including hyperspectral imaging), is being deployed to, non-invasively, detect and diagnose plant responses to abiotic and biotic stressors. Early and accurate detection and diagnosis of stressors are key objectives. Level of radiometric repeatability of optical sensing data and ability to accurately detect and diagnose biotic stress are inversely correlated. Accordingly, it may be argued that one of the most significant frontiers and challenges regarding widespread adoption of optical sensing in plant research and crop production hinges on methods to maximize radiometric repeatability. In this study, we acquired hyperspectral optical sensing data at noon and midnight from soybean (Glycine max) and coleus wizard velvet red (Solenostemon scutellarioides) plants with/without experimentally infestation of two-spotted spider mites (Tetranychus urticae). We addressed three questions related to optimization of radiometric repeatability: (1) are reflectance-based plant responses affected by time of optical sensing? (2) if so, are plant responses to two-spotted spider mite infestations (biotic stressor) more pronounced at midnight versus at noon? (3) Is detection of biotic stress enhanced by spatial binning (smoothing) of hyperspectral imaging data? Results from this study provide insight into calculations of radiometric repeatability. Results strongly support claims that acquisition of optical sensing data to detect and characterize stress responses by plants to detect biotic stressors should be performed at night. Moreover, the combination of midnight imaging and spatial binning increased classification accuracies with 29% and 31% for soybean and coleus, respectively. Practical implications of these findings are discussed. Study results are relevant to virtually all applications of optical sensing to detect and diagnose abiotic and biotic stress responses by plants in both controlled environments and in outdoor crop production systems.

Las plantas deben hacer frente a multitud de estreses en la naturaleza. Entre ellos, las plagas de artrópodos fitófagos causan pérdidas importantes en la calidad y el rendimiento de los cultivos. En concreto, el ácaro Tetranychus urticae, conocido como araña roja constituye una de las principales plagas a nivel mundial, con capacidad de alimentarse de más de 1.100 plantas diferentes, incluyendo alrededor de 150 especies de interés agronómico. Está considerado una de las amenazas agrícolas más importantes ya que tiene un ciclo de vida corto, una elevada tasa de reproducción y una capacidad extraordinaria para desarrollar resistencia a pesticidas. Además, T. urticae es una especie modelo dentro de los Chelicerata fitófagos ya que su genoma está secuenciado y se dispone de una amplia gama de herramientas y protocolos para trabajar con esta especie. Asimismo, la capacidad de la araña roja para alimentarse de la especie modelo Arabidopsis thaliana y la cantidad de herramientas disponibles para esta especie vegetal nos ofrecen una excelente oportunidad para el estudio funcional en la interacción entre plantas y ácaros. En esta tesis, hemos tratado de discernir cómo las plantas se defienden frente al ataque de la araña roja a diferentes niveles de la ruta de transducción de señales (percepción, señalización y moléculas de defensa final). Como punto de partida, hemos utilizado el análisis de la expresión génica diferencial en respuesta al ataque de T. urticae en dos accesiones de Arabidopsis (Bla-2, resistente y Kon, susceptible). Este análisis transcriptómico nos ha permitido buscar, identificar y seleccionar genes candidatos involucrados en la defensa de Arabidopsis frente a la araña roja. En este contexto, se han caracterizado genes que codifican receptores de plantas, compuestos implicados en defensa, en la señalización hormonal, en el equilibrio de especies reactivas de oxígeno y nitrógeno y diferentes moléculas con propiedades acaricidas que afectan directamente a la fisiología del ácaro. Además, los bioensayos realizados con plantas de Arabidopsis que sobre-expresan o silencian los genes candidatos, han demostrado su papel en la defensa de la planta frente a la araña roja y han revelado la compleja red que se establece entre ellos para la supervivencia de la planta en condiciones subóptimas. Finalmente, se han estudiado las contra-defensas establecidas por T. urticae frente algunos de estos genes defensivos. ----------ABSTRACT---------- As sessile organisms, plants must cope with multiple and simultaneous stresses in nature. Among them, biotic stresses and specifically pests cause substantial yield losses. In particular, the two-spotted spider mite (Tetranychus urticae) is an extremely polyphagous species found worldwide that feeds on nearly 1,100 documented host plants, including about 150 agronomically important crops. It is considered one of the most significant agricultural threats since it has a short life cycle, high offspring production, and an extraordinary ability to develop pesticide resistance. In addition, T. urticae is a model within chelicerate herbivores because its genome sequenced and a broad range of tools and protocols developed. Mite ability to feed on Arabidopsis thaliana and the wide available toolkits for this plant species have provided an outstanding opportunity for functional studies of plant-mite interaction. In this thesis, we try to elucidate how plants defend themselves against pest attack at different levels of the signal transduction pathway (perception, signaling and final defence molecules). As starting point, a microarray generated with the natural Arabidopsis accessions (Bla-2 and Kon) at the opposite ends of the resistance spectrum against T. urticae was used to search differential expressed genes. This transcriptomic dataset has allowed the identification and selection of candidate genes involved in Arabidopsis defense against spider mites. Thus, genes encoding plant receptors, compounds involved in defense and hormonal signaling and in the ROS/RNS balance, and different defensive molecules with acaricide properties directly target the mite phytophagous physiology has been characterized. Besides, Arabidopsis-mite bioassays using over-expressing and silencing plants have demonstrated their defense role against the phytophagous, and the intricate network among these genes developed for the plant survival under suboptimal conditions. Finally, the contra-defences settled by T. urticae against some of these defensive genes have been also studied.

The larvae of the black soldier fly (BSFL) can efficiently convert food waste into valuable biomass. They are also an alternative source of fat, protein, and chitin, but little is known about the total microbiota of the whole BSFL and its impact on the microbiological safety of food and feed. This study was conducted to determine bacterial microbiota dynamics of the whole BSFL and frass residues during the industrial rearing process, including the effects of thermal treatment, counts and identification of cultivable bacteria, and the presence of antibiotic resistance genes (ARGs). The second and the fourth instar larvae, frozen and dried fourth instar larvae, and frass samples were examined. The composition of the total bacterial microbiota in BSFL samples was similar and dominated by Proteobacteria while in frass Firmicutes prevailed. The lowest diversity was observed in the second instar larvae and the highest in the frass. The samples showed a relatively low bacterial community diversity. In agreement with the analysis of the total microbiota, the isolated cultivable bacterial strains were members of Proteus , Providencia , Morganella , Staphylococcus , Klebsiella , Enterococcus , and Bacillus genera. The counts of cultivable bacteria increased during the growth of larvae and were similar in the fourth instar larvae and frass residues. Dried larvae had the lowest number of viable counts and were dominated by spore-forming bacteria. The determined viable aerobic counts meet the criteria for edible insects. ARGs conferring resistance to aminoglycosides ( aac-aph ), β-lactams ( blaZ ), erythromycin ( ermA ), tetracycline ( tetM , tetW ), and vancomycin ( vanA , vanB ) were detected by PCR, with the highest diversity and detection rate in frass. The gene tetM was the most widespread and detected in all groups of the tested samples. The results of this work extend the scarce knowledge about the dynamics of microorganisms and ARGs in the industrial-scale food waste upcycling process by BSFL.

Sunflower production plays an important role in global industrial oil production. Two-spotted spider mite, Tetranychus urticae, is a dangerous, polyphagous arthropod pest with a cosmopolitan distribution, which can endanger the economic features of global sunflower production. It is widely known that pests trigger various reactions in host plants. Among these, detection of ultra-weak photon emission (UPE) enhanced upon infestation is a novel, non-invasive method suitable for the visualisation and monitoring of both biotic and abiotic stress in living tissues. In the present study, the increase in ultra-weak UPE triggered by biotic stress caused by T. urticae in Helianthus annuus was measured. UPE response of injured plants differed from that of the control plants, which was reflected by a difference in bioluminescence intensity. In leaves attacked by T. urticae the onset value of average photon count detected by the sensor and expressed in cps (counts per second) was one order of magnitude higher on average as compared to that revealed by uninjured leaves. Furthermore, UPE emission in infested leaves resulted in an abrupt decrease in the ultra-weak photon emission intensity when assayed as a function of time. The use of this non-invasive imaging technique has allowed the detection of the injury induced by T. urticae, as a biotic stressor.

Plant immunity depends on fast and specific transcriptional reprogramming triggered by the perception of biotic stresses. Numerous studies have been conducted to better understand the response of plants to the generalist herbivore two-spotted spider mite (Tetranychus urticae). However, how plants perceive mites and how this perception is translated into changes in gene expression are largely unknown. In this work, we identified a gene induced in Arabidopsis (Arabidopsis thaliana) upon spider mite attack that encodes a two-domain protein containing predicted lectin and Toll/Interleukin-1 receptor domains. The gene, previously named PP2-A5, belongs to the Phloem Protein2 family. Biotic assays showed that PP2-A5 confers tolerance to T. urticae Overexpression or knockout of PP2-A5 leads to transcriptional reprogramming that alters the balance of hormone accumulation and corresponding signaling pathways. The nucleocytoplasmic location of this protein supports a direct interaction with regulators of gene transcription, suggesting that the combination of two putative signaling domains in a single protein may provide a novel mechanism for regulating gene expression. Together, our results suggest that PP2-A5 improves the ability to defend against T. urticae by participating in the tight regulation of hormonal cross talk upon mite feeding. Further research is needed to determine the mechanism by which this two-domain protein functions and to clarify its molecular role in signaling following a spider mite attack.

Tetranychus urticae Koch (two-spotted spider mite) is an agricultural pest with a host range of over 1100 species of plants. Tetranychus urticae has rapidly developed resistance to a variety of synthetic chemical pesticides due to its high fecundity and short generation time. Plant essential oils have been recognized as a novel natural source of pest control that have a reduced impact to the environment and human health compared to synthetic pesticide application, and which may provide a viable alternative for managing T. urticae. The present study assessed the potential of a plant-derived product (product 102) as an acaricide, through topical and residual bioassays on a variety of plant species including common bean plant (Phaseolus vulgaris L.), lettuce (Lactuca sativa L.), tomato (Solanum lycopersicum L.), kale (Brassica oleracea L.), cucumber (Cucumis sativus L.), hops (Humulus lupulus L.) and hemp (Cannabis sativa L.). The results of our study indicate that C. sativa is not a suitable plant to host T. urticae. Product 102 was determined to be effective at preventing the growth of two known fungal species of economic concern (Cladosporium herbarum Persoon and Botrytis cinerea Persoon). By conducting acute contact toxicity tests, we also determined that product 102 is significantly less toxic to Bombus impatiens Cresson compared to the commonly used synthetic insecticide imidacloprid.

Spatial response of Medicago truncatula plants to drought and spider mite attack