Project description:The pathological interaction between oak trees and Phytophthora cinnamomi has implications in the cork oak decline observed over the last decades in the Iberian Peninsula. During host colonization, the phytopathogen secretes effector molecules like elicitins to increase disease effectiveness. The objective of this study was to unravel the proteome changes associated to with the cork oak immune response triggered by P. cinnamomi inoculation in a long-term assay, through SWATH-MS quantitative proteomics performed in the oak leaves. Using the Arabidopis thaliana proteome database as a reference, 424 proteins have been confidently quantified in cork oak leaves, of which 80 proteins showed a p-value below 0.05 or a fold-change greater than 2 or less than 0.5 in their levels between control and inoculated samples being considered as altered. The inoculation of cork oak roots with P. cinnamomi increased the levels of proteins associated with protein-DNA complex assembly, lipid oxidation, response to endoplasmic reticulum stress, and pyridine-containing compound metabolic process in the leaves. In opposition, several proteins associated with cellular metabolic compound salvage and monosaccharide catabolic process had significantly decreased abundances. The most significant abundance variations were observed for the Ribulose 1,5-Bisphosphate Carboxylase small subunit (RBCS1A), Heat Shock protein 90-1 (Hsp90-1), Lipoxygenase 2 (LOX2) and Histone superfamily protein H3.3 (A8MRLO/At4G40030) revealing a pertinent role for these proteins in the host-pathogen interaction mechanism. This work represents the first SWATH-MS analysis performed in cork oak plants inoculated with P. cinnamomi and highlights host proteins that have a relevant action in the homeostatic states that emerge from the interaction between the oomycete and the host in the long term and in a distal organ.
Project description:The periderm is basic for land plants due to its protective role during radial growth, which is achieved by the polymers deposited in the cell walls. Despite the research on the topic has unravelled the role of several enzymes and transcription factors, many questions remain open, especially those regarding cell development. Here we use the outer bark of cork oak (cork), holm oak (rhytidome), and their natural hybrids’ to further understand the mechanisms underlying periderm development. Cork is an outstanding model as it consists of a thick and very homogeneous periderm produced by a permanent mother-cell layer (phellogen). Conversely, holm oak contains a more heterogeneous bark including several thin periderms mixed with phloem, also known as a rhytidome. The inclusion of hybrid samples showing rhytidome-type and cork-type barks is valuable to approach cork development, allowing an accurate identification of candidate genes and processes. The present study underscores that biotic stress and cell death signalling are enhanced in rhytidome-type barks while lipid metabolism and cell cycle are enriched in cork-type barks. Based on the DEGs most expressed related to development, we highlight that cell division, cell expansion, and cell differentiation could account for the differences found between cork and rhytidome-type barks.
Project description:Holm oak (Quercus ilex) is the most important and representative specie of the Mediterranean forest and of the Spanish agrosilvo-pastoral ecosystem “Dehesa”. Despite its environmental and economic interest, Holm oak is still an orphan species whose biology is very little known, especially at the molecular level. In this research, we have performed a shotgun proteomic approach (nLC-MSMS, Orbitrap) to analyze the Holm oak proteome, using, as starting material, a pool generated by mixing equal amounts of homogenized tissue, including embryo, cotyledons (from mature acorns), and leaves and roots (from 6-month old plantlets grown in a greenhouse under environmental conditions). The proteome generated will be the bases of further studies on population variability, growth, development and responses to stresses in this species.
Project description:This work aimed to characterize the molecular adaptations occurring in cork oak (Quercus suber) stems in adaptation to drought, and identify key genetic pathways regulating phellem development. One-year-old cork oak plants were grown for additional 6 months under well-watered (WW) or water-deficit (WD) conditions and main stems were targeted for transcriptomic analysis. WD had a negative impact on secondary growth, decreasing the activity of the vascular cambium and phellogen. Following a tissue-specific approach, we analyzed the transcriptional changes imposed by WD in phellem (outer bark), inner bark, and xylem, and found a global downregulation of genes related to cell division, cell wall biogenesis, lignin and/or suberin biosynthesis. Phellem and phloem showed a concerted upregulation of photosynthesis-related genes, suggesting a determinant role of stem photosynthesis in the adaptation of young plants to long-term drought. The data gathered will be important to further harness the diverse genetic background of this species for the development of optimized management practices.