We have used suspension-cultured parsley cells (Petroselinum crispum) and an oligopeptide elicitor derived from a surface glycoprotein of the phytopathogenic fungus Phytophthora megasperma f.sp. glycinea to study the signaling pathway from elicitor recognition to (Fig. 1). Following leaf inoculation with fungal zoospores, cyst formation, germination, and formation of appressoria and infection vesicles (-4

A heterologous probe encoding phenylalanine ammonia-lyase (PAL) was used to identify PAL clones in cDNA libraries made with RNA from young leaf tissue of two Populus delfoides X P. trichocarpa F1 hybrid clones. Sequence analysis of a 2.4-kb cDNA confirmed its identity as a full-length PAL clone. The predicted amino acid sequence is conserved in comparison with that of PAL genes from several other plants. Southern blot analysis of popular genomic DNA from parenta1 and hybrid individuals, restriction site polymorphism in PAL cDNA clones, and sequence heterogeneity in the 3' ends of several cDNA clones suggested that PAL is encoded by at least two genes that can be distinguished by Hindlll restriction site polymorphisms. Clones containing each type of PAL gene were isolated from a poplar genomic library. Analysis of the segregation of PAL-specific Hindlll restriction fragment-length polymorphisms demonstrated the existence of two independently segregating PAL loci, one of which was mapped to a linkage group of the poplar genetic map. Developmentally regulated PAL expression in poplar was analyzed using RNA blots. Highest expression was observed in young stems, apical buds, and young leaves. Expression was lower in older stems and undetectable in mature leaves. Cellular localization of PAL expression by in situ hybridization showed very high levels of expression in subepidermal cells of leaves early during leaf development. In stems and petioles, expression was associated with subepidermal cells and vascular tissues.The enzyme PAL (EC 4.3.1.5) plays a key role in linking primary metabolism to phenylpropanoid metabolism by catalyzing the deamination of L-Phe to produce trans-cinnamic acid. This reaction is considered a key step in phenylpropanoid metabolism (Jones, 1984;Hahlbrock and Scheel, 1989) because it provides an entry point for the biosynthesis of a large number of natural products derived from the phenylpropane skeleton. Consistent with the diverse roles played by these phenylpropanoid-derived compounds, PAL enzyme levels are under both developmental and environmental control (Hahlbrock and Scheel, 1989). The accumulation of PAL mRNA and the activity of PAL promoters varies during the

The transcription rates of numerous plant genes have previously been shown to be strongly affected by pathogen infection or elicitor treatment. Here we estimate the extent and complexity of this response by analyzing the patterns of mRNA induction in fungal elicitor-treated parsley cells (Petroselinum crispum) for several representatives from various primary and secondary metabolic pathways, cytosolic as well as plastidic. As a reference, we use the biphasic accumulation curve for the coordinately induced mRNAs encoding the three core enzymes of general phenylpropanoid metabolism, phenylalanine ammonia-lyase, cinnamate 4-hydroxylase and 4-coumarate:CoA ligase. Coincidence with this curve was observed for the mRNA induction kinetics of several, but not all, phenylpropanoid branch pathway-related reactions, whereas seven selected mRNAs from the pentose phosphate, glycolytic and shikimate pathways, including various cytosolic and plastidic isoforms, were induced with great differences in timing. Likewise unique and dissimilar from the reference curve were the induction patterns for various mRNAs encoding enzymes or proteins that are either more distantly or not at all related to phenylpropanoid metabolism. None of over 40 mRNAs tested so far remained unaffected. Using one strongly elicitor-responsive mRNA from carbohydrate metabolism, encoding a cytosolic glucose 6-phosphate dehydrogenase, for in situ RNA/RNA hybridization in fungus-infected parsley leaf tissue, we observed again the previously reported, close simulation of metabolic changes in true plant/fungus interactions by elicitor treatment of cultured cells. In addition to demonstrating extensive, highly complex functional, temporal and spatial patterns of changes in gene expression in infected plant cells, these results provide valuable information for the identification of pathogen-responsive promoters suitable for gene technology-assisted resistance breeding.

Parsley (Petroselinum crispum) plants and suspension-cultured cells have been used extensively for studies of non-host-resistance mechanisms in plant͞pathogen interactions. We now show that treatment of cultured parsley cells with a defined peptide elicitor of fungal origin causes rapid and large changes in the levels of various unsaturated fatty acids. While linoleic acid decreased and linolenic acid increased steadily for several hours, comparatively sharp increases in oleic acid followed a biphasic time course. In contrast, the overall level of stearic acid remained unaffected. Using a PCR-based approach, a parsley cDNA was isolated sharing high sequence similarity with -3 fatty acid desaturases. Subsequent isolation and characterization of a fulllength cDNA enabled its functional identification as a plastidlocalized -3 fatty acid desaturase by complementation of the Arabidopsis thaliana fad7͞8 double mutant which is low in trienoic fatty acids. -3 Fatty acid desaturase mRNA accumulated rapidly and transiently in elicitor-treated cultured parsley cells, protoplasts, and leaves, as well as highly localized around fungal infection sites in parsley leaf buds. These results indicate that unsaturated fatty acid metabolism is yet another component of the highly complex, transcriptionally regulated pathogen defense response in plants.

BackgroundBreast cancer is a heterogeneous disease displaying distinct molecular features and clinical outcome. The molecular profile of triple-negative breast cancers (TNBCs) overlaps with that of basal-like breast cancers that in turn show similarities with high-grade serous ovarian and endometrial carcinoma. L1CAM is an established biomarker for the latter cancers and we showed before that approximately 18% of primary breast cancers are positive for L1CAM and have a bad prognosis. Here we analysed the expression of L1CAM breast cancer subtypes.MethodsWe analyzed mRNA and protein expression data from different breast cancer cohorts for L1CAM, estrogen receptor, progesterone receptor, Her-2 and Androgen receptor (AR) and correlated the data. We performed Western blot analysis on tumor cell lysates and carried out chromatin-immuno-precipitation (CHIP) after AR overexpression.ResultsWe find that L1CAM is expressed preferentially though not exclusively in TNBCs. Using the human cancer genome atlas database and two independent breast cancer cohorts we find that L1CAM is inversely correlated with androgen receptor (AR) expression. We found that L1CAMhighARlow primary breast tumors have the worst clinical outcome. Overexpression of AR in MDA-MB436 breast cancer cells decreased L1CAM expression at the protein and mRNA level and CHIP-analysis revealed binding of AR to the L1CAM promoter region.ConclusionsThese results suggest that L1CAM in breast cancer is under AR control. The data also strongly advocate the use of L1CAM assessment in breast cancer diagnosis. We suggest that L1CAM expression could be causally related to the bad prognosis of TNBCs.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-958) contains supplementary material, which is available to authorized users.