Hormonal dynamics after Plasmodiophora brassicae infection were compared in two Brassica napus cultivars-more resistant SY Alister and more sensitive Hornet, in order to elucidate responses associated with efficient defense. Both cultivars responded to infection by the early transient elevation of active cytokinins (predominantly cis-zeatin) and auxin indole-3-acetic acid (IAA) in leaves and roots, which was longer in Hornet. Moderate IAA levels in Hornet roots coincided with a high expression of biosynthetic gene nitrilaseNIT1 (contrary to TAA1, YUC8, YUC9). Alister had a higher basal level of salicylic acid (SA), and it stimulated its production (via the expression of isochorismate synthase (ICS1)) in roots earlier than Hornet. Gall formation stimulated cytokinin, auxin, and SA levels-with a maximum 22 days after inoculation (dai). SA marker gene PR1 expression was the most profound at the time point where gall formation began, in leaves, roots, and especially in galls. Jasmonic acid (JA) was higher in Hornet than in Alister during the whole experiment. To investigate SA and JA function, SA was applied before infection, and twice (before infection and 15 dai), and JA at 15 dai. Double SA application diminished gall formation in Alister, and JA promoted gall formation in both cultivars. Activation of SA/JA pathways reflects the main differences in clubroot resistance.
- MeSH
- Aminohydrolases genetics MeSH
- Brassica napus growth & development metabolism parasitology MeSH
- Cyclopentanes analysis MeSH
- Cytokinins analysis MeSH
- Intramolecular Transferases genetics MeSH
- Plant Roots growth & development metabolism parasitology MeSH
- Indoleacetic Acids analysis MeSH
- Plant Leaves growth & development metabolism parasitology MeSH
- Plant Diseases parasitology MeSH
- Disease Resistance MeSH
- Oxylipins analysis MeSH
- Plasmodiophorida pathogenicity MeSH
- Gene Expression Regulation, Plant MeSH
- Plant Growth Regulators analysis MeSH
- Plant Proteins genetics MeSH
- Gene Expression Regulation, Developmental MeSH
- Publication type
- Journal Article MeSH
- Comparative Study MeSH
Plasmodiophora brassicae is a soil-borne pathogen that belongs to Rhizaria, an almost unexplored eukaryotic organism group. This pathogen requires a living host for growth and multiplication, which makes molecular analysis further complicated. To broaden our understanding of a plasmodiophorid such as P. brassicae, we here chose to study immunophilins, a group of proteins known to have various cellular functions, including involvement in plant defense and pathogen virulence. Searches in the P. brassicae genome resulted in 20 putative immunophilins comprising of 11 cyclophilins (CYPs), 7 FK506-binding proteins (FKBPs) and 2 parvulin-like proteins. RNAseq data showed that immunophilins were differentially regulated in enriched life stages such as germinating spores, maturing spores, and plasmodia, and infected Brassica hosts (B. rapa, B. napus and B. oleracea). PbCYP3 was highly induced in all studied life stages and during infection of all three Brassica hosts, and hence was selected for further analysis. PbCYP3 was heterologously expressed in Magnaporthe oryzae gene-inactivated ΔCyp1 strain. The new strain ΔCyp1+ overexpressing PbCYP3 showed increased virulence on rice compared to the ΔCyp1 strain. These results suggest that the predicted immunophilins and particularly PbCYP3 are activated during plant infection. M. oryzae is a well-studied fungal pathogen and could be a valuable tool for future functional studies of P. brassicae genes, particularly elucidating their role during various infection phases.
- MeSH
- Brassica classification parasitology MeSH
- Cyclophilins classification genetics metabolism MeSH
- Phylogeny MeSH
- Immunophilins genetics metabolism MeSH
- Host-Pathogen Interactions MeSH
- Plant Roots parasitology MeSH
- Plant Diseases parasitology MeSH
- Plasmodiophorida genetics metabolism physiology MeSH
- Protozoan Proteins genetics metabolism MeSH
- Gene Expression Regulation MeSH
- Amino Acid Sequence MeSH
- Sequence Homology, Amino Acid MeSH
- Spores, Protozoan genetics MeSH
- Gene Expression Profiling methods MeSH
- Publication type
- Journal Article MeSH
Fungi, nematodes and oomycetes belong to the most prominent eukaryotic plant pathogenic organisms. Unicellular organisms from other eukaryotic lineages, commonly addressed as protists, also infect plants. This review provides an introduction to plant pathogenic protists, including algae infecting oomycetes, and their current state of research.
Plants as non-mobile organisms constantly integrate varying environmental signals to flexibly adapt their growth and development. Local fluctuations in water and nutrient availability, sudden changes in temperature or other abiotic and biotic stresses can trigger changes in the growth of plant organs. Multiple mutually interconnected hormonal signaling cascades act as essential endogenous translators of these exogenous signals in the adaptive responses of plants. Although the molecular backbones of hormone transduction pathways have been identified, the mechanisms underlying their interactions are largely unknown. Here, using genome wide transcriptome profiling we identify an auxin and cytokinin cross-talk component; SYNERGISTIC ON AUXIN AND CYTOKININ 1 (SYAC1), whose expression in roots is strictly dependent on both of these hormonal pathways. We show that SYAC1 is a regulator of secretory pathway, whose enhanced activity interferes with deposition of cell wall components and can fine-tune organ growth and sensitivity to soil pathogens.
- MeSH
- Arabidopsis genetics growth & development metabolism MeSH
- Cell Wall chemistry metabolism MeSH
- Cytokinins metabolism MeSH
- Endosomes metabolism MeSH
- Plants, Genetically Modified metabolism MeSH
- Golgi Apparatus metabolism MeSH
- Plant Roots metabolism microbiology MeSH
- Indoleacetic Acids metabolism MeSH
- Membrane Proteins genetics metabolism MeSH
- Disease Resistance genetics MeSH
- Plasmodiophorida pathogenicity MeSH
- Arabidopsis Proteins genetics metabolism MeSH
- Soil MeSH
- Gene Expression Regulation, Plant genetics MeSH
- Plant Growth Regulators metabolism MeSH
- Secretory Pathway genetics MeSH
- Gene Expression Profiling MeSH
- Transcriptome genetics MeSH
- Vesicular Transport Proteins metabolism MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
