A Phytophthora effector promotes homodimerization of host transcription factor StKNOX3 to enhance susceptibility

Abstract

Oomycete pathogens secrete hundreds of cytoplasmic RxLR effectors to modulate host immunity by targeting diverse plant proteins. Revealing how effectors manipulate host proteins is pivotal to understand infection processes and to develop new strategies to control plant disease. Here we show that the Phytophthora infestans RxLR effector Pi22798 interacts in the nucleus with a potato class II knotted-like homeobox (KNOX) transcription factor, StKNOX3. Silencing the orthologue NbKNOX3 in Nicotiana benthamiana reduces host colonization by P. infestans, whereas transient and stable overexpression of StKNOX3 enhances infection. StKNOX3 forms a homodimer which is dependent on its KNOX II domain. The KNOX II domain is also essential for Pi22798 interaction and for StKNOX3 to enhance P. infestans colonization, indicating that StKNOX3 homodimerization contributes to susceptibility. However, critically, the effector Pi22798 promotes StKNOX3 homodimerization, rather than heterodimerization to another KNOX transcription factor StKNOX7. These results demonstrate that the Oomycete effector Pi22798 increases pathogenicity by promoting homodimerization specifically of StKNOX3 to enhance susceptibility.

Identification of miRNAs Involving Potato-Phytophthora infestans Interaction

“…For the degradation of predicted target genes by miRNA assay, the miRNA vector final concentration of OD 600 was 0.1 and the final concentration for the target vector OD 600 was 0.05. The agro-infiltration method was the same as Zhou et al [ 62 ].…”

Transcriptional profiling during infection of potato NLRs and Phytophthora infestans effectors using cDNA enrichment sequencing

“…Our comparative analysis between PenSeq and RNAseq reflects the hemibiotrophic nature of the infection. Previously utilised marker genes for the late blight infection progression such as HMP1 , NPP1 and known Avr genes [39,40,44] with a biotrophic expression profile, revealed concordance in their transcriptional behaviour for both RNAseq and PenSeq analyses (Figure 3, Supplementary Figure 3, Table S2).…”

Ralstonia solanacearum effector RipAK suppresses homodimerization of the host transcription factor ERF098 to enhance susceptibility and the sensitivity of pepper plants to dehydration

“…It has been reported that TFs can directly associate with themselves to form homodimers (Piepoli et al., 2022; Zhou et al., 2022). BiFC and pull‐down assays were performed to investigate whether this was also the case for ERF098 (Figure 4).…”