The immunophilin repertoire of Plasmodiophora brassicae and functional analysis of PbCYP3 cyclophilin

Abstract

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.Electronic supplementary materialThe online version of this article (10.1007/s00438-017-1395-0) contains supplementary material, which is available to authorized users.

Demystifying biotrophs: FISHing for mRNAs to decipher plant and algal pathogen–host interaction at the single cell level

“…Yet the unavailability of genetic manipulation of the parasite forces all functional studies to be conducted on transformed plant hosts (mainly A. thaliana ) either focussing on the host side of the response e.g. 26 or by overexpressing P. brassicae genes in the host 27 or in other plant pathogenic fungi 28 . Likewise, genome resources are available for brown algae 29 , 30 , but this group yet remains inaccessible to transformation, genome editing or RNAi, to the exception of Fucus zygotes 31 .…”

Molecular Pathotyping of Plasmodiophora brassicae—Genomes, Marker Genes, and Obstacles

“…Through the availability of P. brassicae genomes the molecular investigation of the clubroot pathosystem has made huge progress. Effector candidates have been identified [18,21,33,34] and as methods are in place to characterize them in more detail [32][33][34][71][72][73] more detailed understanding of their function can be expected in the near future. However, in addition to the complications due to the P. brassicae obligate life style, a lack of analyses of P. brassicae genes, missing or difficult access to reported data, and the lack of genome data from a broad range of pathotyped isolates still restricts further progress by the research community.…”

“…The suppression of SA-mediated defenses would facilitate P. brassicae to multiply in the host roots. Another potential effector candidate, the P. brassicae immunophilin-like protein PbCYP3, increased virulence on rice when heterologously expressed in a Magnaporthe oryzae gene-inactivated ∆Cyp1 strain [32].…”

“…The P. brassicae genome contains genes potentially able to manipulate plant hormone metabolism, such as the auxinresponsive Gretchen Hagen 3, isopentenyl-transferases, a SABATH type methyltransferase and cytokinin oxidase [18,21,30]. The investigation of proteins associated with lipid droplet organelles [23] or protein families such as the E3 ubiquitin ligases of P. brassicae [31] or immunophilins [32] also benefitted from the available genome information.…”

Search for Partner Proteins of A. thaliana Immunophilins Involved in the Control of Plant Immunity

“…So far, the functions of plant immunophilins and their role in pathogenesis have been poorly studied. In general, plant immunophilins are involved in basic immunity control, provided by the ability to catalyze isomerization in the polypeptide chains around proline residues via the action of enzymes with peptidyl-prolyl cis/trans isomerase (PPIase) activity [ 17 , 18 ].…”