Phytophthora cinnamomi

Phlomis purpurea L. grows spontaneously in dry and stony habitats from the south of Iberian Peninsula and in cork oak (Quercus suber L.) and holm oak (Q. ilex ssp. rotundifolia, Lam.) plantations infested with Phytophthora cinnamomi (Rands). The aim of this study is to understand the genetic basis of P. purpurea innate immunity to this pathogen. The transcriptome analysis of P. purpurea upon challenging with P. cinnamomi revealed a set of up-regulated genes, related to signaling, transcription factors and response to stress. Transcripts involved in the synthesis of a number of proteins, namely: ANKYRIN, AP2, AQUAPORIN, ARMADILLO, At1G69870-LIKE, BHLH, BON1, CALMODULIN, CALNEXIN, CALRETICULINE, CC-NBS-LRR, CHAPERONE, CYTOCHROME, DUF, GH3, GMP, G-TYPE, LIPOXYGENASE, MLO-LIKE, MYB, NAC, NBS-LRR, PENTATRICOPEPTIDE, SUBTILISIN, WAK, bZIP and hormones such as BRASSINOSTEROID, JASMONATE, SALICYLATE, ETHYLENE-RESPONSIVE were identified. P. purpurea ability to cope with P. cinnamomi attack is based on the expression of a set of transcription factors and signaling molecules targeted by the pathogen. The information gathered contributes to the elucidation of the overall response of P. purpurea to P. cinnamomi attempted infection which can be helpful for improving woody species resistance to pathogenic oomycetes.

This study aimed to elucidate the infection process of the invasive pathogen Phytophthora cinnamomi on primary and secondary roots of 2-month-old Quercus ilex seedlings. To test if different methods of inoculation lead to different changes in the host caused by the pathogen, the root system of plants was either immersed into a suspension of P. cinnamomi zoospores, or placed in direct contact with agar plugs colonized by P. cinnamomi mycelium. Histology of root sections obtained every 24 h for 10 days revealed similar changes in the structure of cells and tissues of the host irrespective of the inoculation method used. However, the immersion method resulted in a delay in the colonization of the host, different aerial symptoms, and the formation of different reproductive structures of the pathogen. Emerging secondary and tertiary roots and sites where secondary or tertiary roots were about to emerge were identified as main entry points. Hyphae in the xylem tissues were more frequently found in secondary than in primary roots, but in both types of roots the phloem was the most important pathway of colonization. For the first time in the interaction between Q. ilex and P. cinnamomi, transmission electron microscopy was used to describe degradation of the host cell walls, pit penetration and extrahaustorial matrix. Haustoria development during intracellular growth and hyphal aggregations (stromata) caused no damage to the host cell walls indicating hemibiotrophic parasitism.

Phytophthora cinnamomi is an alien species, which causes root rot and decline in cork oak (Quercus suber) and holm oak (Quercus ilex) native forests and agroecosystems in the Iberian Peninsula. However, there is little reliable and accessible data on the presence and absence of this soil borne pathogen in Spain. For this reason, we applied the Environmental Niche Models to predict the potential distribution of P. cinnamomi in Andalusia (southern Spain). Firstly, we developed a georeferenced database about presence-absence records of P. cinnamomi in the study area based on published data and from our research projects. Secondly, we developed a set of environmental variables at a resolution of 250 meters. Thirdly, the inferential approach was based on the regression methods using presence-absence data, and the machine learning algorithms using presence-background data, and evaluated the models using ROC/AUC. Finally, we ensembled the best models to mapping the results in one consensus model. The result showed a large potential distribution area of P. cinnamomi in Andalusia, from one-third to one-half of the region and connected areas.

Lipases belong to the family of serine hydrolases, which in turn include various esterase enzymes (E.C.3.1.1.1). They are involved in the cleavage of triacylglycerols to free fatty acids and glycerol in many important biological processes, as for instance routine metabolism of dietary triglycerides to cell signalling and inflammation. Lipases constitute a ubiquitous group of enzymes able to catalyse a number of different reactions, many of them of industrial interest. Particularly, microbial lipases exhibit a wide range of industrial applications, namely in pharmaceutical, food and detergents industry. The aim of this review is to summarize the recent achievements illustrating the importance and the versatility of microbial lipases, including their involvement in infection mechanisms.

Phytophthora cinnamomi Rands causes "avocado tristeza", one of the main phytosanitary problems in Michoacán, Mexico. In the present study the effect of the phosphorous acid in the recovery of avocado trees 'Hass' with initial, intermediate and advanced symptoms were evaluated of tristeza. Phosphorous acid 40% and pH of 5.5 was applied to the dose of 45 mL/tree (7.18 g a.i.) in November 2013. The pseudohongo was isolated from roots

We study the nonequilibrium effects of spin and/or electric currents on the helical indirect exchange interactions of local spins that embedded in general open electronic systems. Especially, besides the synthesized anisotropic Heisenberg interactions, we find that the synthetic helical indirect exchange interactions possess two parts: antisymmetric (Dzyaloshinskii-Moriya interaction) and symmetric (Kaplan-Shekhtman-Entin-Wohlman-Aharony interaction), which are all formulated in terms of Keldysh nonequilibrium Green's functions. The presence of either spin-orbit coupling or spin polarized currents alone is able to synthesize and control the antisymmetric Dzyaloshinskii-Moriya exchange interactions, as the same direction as spin splitting. However, the appearance of symmetric Kaplan-Shekhtman-Entin-Wohlman-Aharony interactions requires both, i.e., the spin-orbit coupling and spin polarized currents with different splitting directions. Our results show the detailed scheme of controlling the sign, magnitude, and direction of indirect Dzyaloshinskii-Moriya vectors and Kaplan-Shekhtman-Entin-Wohlman-Aharony interactions at nonequilibrium in open quantum devices.

Phytophthora cactorum, Ph. cambivora, Ph. cinnamomi, Ph. citricola, Ph. cryptogea, Ph. drechsleri, Ph. infestans, Ph. megasperma, Ph. parasitica and Ph. syringae contain GSH-conjugation systems as indicated by the presence of active GST enzyme in addition to GSH. Basal levels of both GSH and GST in the thalli of Phytophthora strains studied did not correlate with either fungal sensitivity to phenylamides (acetochlor, butachlor, metolachlor, metachlor, propachlor, ofurace, CGA-28212, metalaxyl, RE-26745, benalaxyl, furalaxyl, LAB-149203) or their acquired resistance to metalaxyl. Thalli of Phytophthora strains from axenic cultures exposed to sublethal concentrations of the above pesticides contained significantly higher levels of both GSH and GSR than untreated controls. This response was independent of the sensitivity and tolerance of the strains to phenylamides.
When the responses of Phytophthora strains to phenylamide chemicals were compared by means of principal component analysis, four independent components were detected accounting for 88 % of total variation. Biological propertes (basal and induced levels of GST and GSH, growth intensity, degree of acquired resistance to metalaxyl, sensitivity to propiconazole and to cis- and trans-tridemorph) of the strains contributed differently to this variation. It was concluded that, in contrast to plants, sensitivity or tolerance of Phytophtora species to phenylamide pesticides is not regulated by the efficiency of the GST-conjugation system. In addition, our data clearly indicate that the acetanilide pesticides have multiple sites of action in the Phytophthora genus.

Soil-borne pathogens are a key component of the belowground community because of the significance of their ecological and socio-economic impacts. However, very little is known about the complexity of their distribution patterns in natural systems. Here, we explored the patterns, causes and ecological consequences of spatial variability in pathogen abundance in Mediterranean forests affected by oak decline.

We used spatially explicit neighborhood models to predict the abundance of soil-borne pathogen species (Phytophthora cinnamomi, Pythium spiculum and Pythium spp.) as a function of local abiotic conditions (soil texture) and the characteristics of the tree and shrub neighborhoods (species composition, size and health status). The implications of pathogen abundance for tree seedling performance were explored by conducting a sowing experiment in the same locations in which pathogen abundance was quantified.

Pathogen abundance in the forest soil was not randomly distributed, but exhibited spatially predictable patterns influenced by both abiotic and, particularly, biotic factors (tree and shrub species). Pathogen abundance reduced seedling emergence and survival, but not in all sites or tree species.

Our findings suggest that heterogeneous spatial patterns of pathogen abundance at fine spatial scale can be important for the dynamics and restoration of declining Mediterranean forests.