A Role in Immunity for Arabidopsis Cysteine Protease RD21, the Ortholog of the Tomato Immune Protease C14

Secreted papain-like Cys proteases are important players in plant immunity. We previously reported that the C14 protease of tomato is targeted by cystatin-like EPIC proteins that are secreted by the oomycete pathogen Phytophthora infestans (Pinf) during infection. C14 has been under diversifying selection in wild potato species coevolving with Pinf and reduced C14 levels result in enhanced susceptibility for Pinf. Here, we investigated the role C14-EPIC-like interactions in the natural pathosystem of Arabidopsis with the oomycete pathogen Hyaloperonospora arabidopsidis (Hpa). In contrast to the Pinf-solanaceae pathosystem, the C14 orthologous protease of Arabidopsis, RD21, does not evolve under diversifying selection in Arabidopsis, and rd21 null mutants do not show phenotypes upon compatible and incompatible Hpa interactions, despite the evident lack of a major leaf protease. Hpa isolates express highly conserved EPIC-like proteins during infections, but it is unknown if these HpaEPICs can inhibit RD21 and one of these HpaEPICs even lacks the canonical cystatin motifs. The rd21 mutants are unaffected in compatible and incompatible interactions with Pseudomonas syringae pv. tomato, but are significantly more susceptible for the necrotrophic fungal pathogen Botrytis cinerea, demonstrating that RD21 provides immunity to a necrotrophic pathogen

Identification of Gene Modules Associated with Drought Response in Rice by Network-Based Analysis

Understanding the molecular mechanisms that underlie plant responses to drought stress is challenging due to the complex interplay of numerous different genes. Here, we used network-based gene clustering to uncover the relationships between drought-responsive genes from large microarray datasets. We identified 2,607 rice genes that showed significant changes in gene expression under drought stress; 1,392 genes were highly intercorrelated to form 15 gene modules. These drought-responsive gene modules are biologically plausible, with enrichments for genes in common functional categories, stress response changes, tissue-specific expression and transcription factor binding sites. We observed that a gene module (referred to as module 4) consisting of 134 genes was significantly associated with drought response in both drought-tolerant and drought-sensitive rice varieties. This module is enriched for genes involved in controlling the response of the plant to water and embryonic development, including a heat shock transcription factor as the key regulator in the expression of ABRE-containing genes. These results suggest that module 4 is highly conserved in the ABA-mediated drought response pathway in different rice varieties. Moreover, our study showed that many hub genes clustered in rice chromosomes had significant associations with QTLs for drought stress tolerance. The relationship between hub gene clusters and drought tolerance QTLs may provide a key to understand the genetic basis of drought tolerance in rice

Analysis of cell wall proteins regulated in stem of susceptible and resistant tomato species after inoculation with Ralstonia solanacearum: a proteomic approach

Proteomics approach was used to elucidate the molecular interactions taking place at the stem cell wall level when tomato species were inoculated with Ralstonia solanacearum, a causative agent of bacterial wilt. Cell wall proteins from both resistant and susceptible plants before and after the bacterial inoculation were extracted from purified cell wall with salt buffers and separated with 2-D IEF/SDS–PAGE and with 3-D IEF/SDS/SDS–PAGE for basic proteins. The gels stained with colloidal Coomassie revealed varied abundance of protein spots between two species (eight proteins in higher abundance in resistant and six other in susceptible). Moreover, proteins were regulated differentially in response to bacterial inoculation in resistant (seven proteins increased and eight other decreased) as well as in susceptible plants (five proteins elevated and eight other suppressed). Combination of MALDI-TOF/TOF MS and LC-ESI-IonTrap MS/MS lead to the identification of those proteins. Plants responded to pathogen inoculation by elevating the expression of pathogenesis related, other defense related and glycolytic proteins in both species. However, cell wall metabolic proteins in susceptible, and antioxidant, stress related as well as energy metabolism proteins in resistant lines were suppressed. Most of the proteins of the comparative analysis and other randomly picked spots were predicted to have secretion signals except some classical cytosolic proteins

In-vitro and in-vivo study of the interference between Rift Valley fever virus (clone 13) and Sheeppox/Limpy Skin disease viruses

Abstract Viral interference is a common occurrence that has been reported in cell culture in many cases. In the present study, viral interference between two capripox viruses (sheeppox SPPV and lumpy skin disease virus LSDV in cattle) with Rift Valley fever virus (RVFV) was investigated in vitro and in their natural hosts, sheep and cattle. A combination of SPPV/RVFV and LSDV/RVFV was used to co-infect susceptible cells and animals to detect potential competition. In-vitro interference was evaluated by estimating viral infectivity and copies of viral RNA by a qPCR during three serial passages in cell cultures, whereas in-vivo interference was assessed through antibody responses to vaccination. When lamb testis primary cells were infected with the mixture of capripox and RVFV, the replication of both SPPV and LSDV was inhibited by RVFV. In animals, SPPV/RVFV or LSDV/RVFV combinations inhibited the replication SPPV and LSDV and the antibody response following vaccination. The combined SPPV/RVFV did not protect sheep after challenging with the virulent strain of SPPV and the LSDV/RVFV did not induce interferon Gamma to LSDV, while immunological response to RVFV remain unaffected. Our goal was to assess this interference response to RVFV/capripoxviruses’ coinfection in order to develop effective combined live-attenuated vaccines as a control strategy for RVF and SPP/LSD diseases. Our findings indicated that this approach was not suitable for developing a combined SPPV/LSDV/RVFV vaccine candidate because of interference of replication and the immune response among these viruses

Chemical composition and effect of liquid and vapor phase of Lavandula multifida essential oil on mycelial growth of fungi responsible for the rot of apple

International audienceThis work aims to study the chemical composition and the antifungal activity of Lavandula multifida essential oil against three fungal decays of apples in post-harvest according to two methods: direct contact in agar médium and micro-atmosphère. This species has provided an essential oil with a yield of 2.4%. The chromatographic analysis (GC and GC/MS) of this essential oil has identified 28 constituents, accounting more than 90 % in total oil, which caravacrol (57.9 %) was the most principal component. The results obtained showed that the essential oil has a significant inhibition of the mycelial growth of all strains (p< 0.05).The minimum inhibitory concentration (MIC) of this oil is 0.125 μL/mL of air against the three strains tested when using microatmosphere method. In contrast, MICs are 0.125 μL/ mL for Alternaria sp., and 0.25μL/mL for Penicillium expansum and Rhizopus stlonifer when using the direct contact method. This antifungal activity is due mainly to the richness of this essential oil in carvacrol known for its effectiveness against the microbial agents

Caractérisation d'une collection de tomates issues de différentes régions du Maroc

Tomatoes are one of the most important crops in Morocco. National tomato production reached 1 231 250 tons in 2019. The sector generates thousands of jobs and is one of the pillars of the country's economy through exports. Hence, it is judicious to search for new varieties with high commercial potential. This study aimed to characterize a collection of four local tomato genotypes (‘Taliouine’, ‘Zagora’, ‘Oufella’ and ‘Cerise or Cherry tomato’) from accessions collected in different regions of Morocco, compared to two commercial genotypes (‘Campbell 33’ and ‘Rio Grande’). The analyses concerned agronomic and growth criteria, sensory criteria and physical and physicochemical criteria (humidity, pH, Brix and color). The obtained results showed a great variability between the studied genotypes. Some genotypes showed interesting performances like ‘Campbell 33’ (number of leaves per branch), ‘Rio Grande’ (number of fruits per plant), ‘Cerise tomato’ (number of fruiting branches per plant) and ‘Taliouine’ (plant height). The three genotypes with the best taste are ‘Campbell 33’, ‘Cerise tomato’ and ‘Oufella’. They also show a high intensity of red color, high skin firmness and high aroma content. Significant variations were also observed for the different physicochemical criteria. Such results will help to identify relevant criteria that can be used for varietal improvement and can also constitute basic criteria to differentiate between tomato accessions.Les tomates sont l’une des cultures les plus importantes au Maroc. La production nationale de tomates a atteint 1 231 250 tons en 2019. Le secteur génère des milliers d’emplois et constitue l’un des piliers de l’économie du pays grâce aux exportations. Il est donc judicieux de rechercher de nouvelles variétés à fort potentiel commercial. Cette étude avait comme objectif la caractérisation d’une collection de quatre génotypes de tomates locales issues d'accessions collectées dans différentes régions du Maroc (‘Taliouine’, ‘Zagora’, ‘Oufella’ et ‘Tomate cerise’), comparée à deux génotypes commerciaux (‘Campbell 33’ et ‘Rio Grande’). Les analyses ont concerné des critères agronomiques et de croissance, des critères sensoriels et des critères physiques et physicochimiques (humidité, pH, Brix et couleur). Les résultats obtenus ont montré une assez grande variabilité entre les différents génotypes étudiés. Certains génotypes ont présenté des performances importantes comme ‘Campbell 33’ (nombre de feuilles par branche), ‘Rio Grande’ (nombre de fruits par plante), ‘Tomate cerise’ (nombre de branches fructifères par plante) et ‘Taliouine’ (hauteur de la plante). Les trois génotypes les mieux appréciés pour leur goût sont ‘Campbell 33’, ‘Tomate cerise’ et ‘Oufella’. Ces derniers montrent une forte intensité au niveau de leur couleur rouge, une peau très ferme et des teneurs élevés en arômes. Des variations significatives ont été également observées pour les différents critères physicochimiques étudiés. De tels résultats aideront à identifier les critères importants qui peuvent être utilisées pour l'amélioration variétale et qui peuvent aussi constituer des critères de base pour différencier entre les accessions de tomates

Spectrum of Clinically Relevant Exophiala Species in the United States▿

Numerous members of the genus Exophiala are potential agents of human and animal mycoses. The majority of these infections are cutaneous and superficial, but also fatal systemic infections are known. We re-identified 188 clinical isolates from the United States, which had a preliminary morphological identification of Exophiala species, by sequencing internal transcribed spacer (ITS) region of the rRNA. Molecular identifications of the strains were as follows, in order of frequency: 55 E. dermatitidis (29.3%), 37 E. xenobiotica (19.7%), 35 E. oligosperma (18.6%), 13 E. lecanii-corni (6.9%), 12 E. phaeomuriformis (6.4%), 7 E. jeanselmei (3.7%), 7 E. bergeri (3.7%), 6 E. mesophila (3.2%), 5 E. spinifera (2.7%), 3 Exophiala sp. 1 (1.6%), 3 E. attenuata (1.6%), 3 Phialophora europaea (1.3%), 1 E. heteromorpha (0.5%), and 1 Exophiala sp. 2 (0.5%) strains. Exophiala strains were repeatedly isolated from deep infections (39.9%) involving lung, pleural fluid, sputum, digestive organs (stomach, intestines, bile), heart, brain, spleen, bone marrow, blood, dialysis fluid, lymph node, joint, breast, middle ear, throat, and intraocular tissues. About 38.3% of the Exophiala spp. strains were agents of cutaneous infections including skin, mucous membranes, nail, and corneal epithelium lesions. The other strains caused superficial infections (0.5%, including hair) or subcutaneous infection (12.0%, including paranasal sinusitis, mycetoma, and subcutaneous cyst). The systemic infections were preponderantly caused by E. dermatitidis, E. oligosperma, E. phaeomuriformis, E. xenobiotica, and E. lecanii-corni. Strains of E. bergeri, E. spinifera, E. jeanselmei, E. mesophila, and E. attenuata mainly induced cutaneous and subcutaneous infections. Since relatively few unknown ITS motifs were encountered, we suppose that the list of opportunistic Exophiala species in temperate climates is nearing completion, but a number of species still have to be described