A plant cell wall-associated kinase encoding gene is dramatically downregulated during nematode infection of potato

Authors: CHEN, SHIYAN - Cornell University; CUI, LILI - Cornell University; Wang, Xiaohong

Submitted to: Plant Signaling and Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2021
Publication Date: 12/29/2021
Citation: Chen, S., Cui, L., Wang, X. 2021. A plant cell wall-associated kinase encoding gene is dramatically downregulated during nematode infection of potato. Plant Signaling and Behavior. 17(1):e2004026. https://doi.org/10.1080%2F15592324.2021.2004026.
DOI: https://doi.org/10.1080%2F15592324.2021.2004026

Interpretive Summary: Plant-parasitic cyst nematodes are devastating plant pests that cause significant crop yield losses annually. These root parasites manipulate various host cellular processes including defense responses to gain successful infection. Plant wall-associated kinases (WAKs) and WAK-like kinases (WAKLs) are important regulators of plant defenses against bacterial and fungal pathogens. However, a role of the WAK/WAKL regulators in plant-nematode interactions is unknown. In this study, we have specifically characterized a WAKL regulator, stWAKL2, from potato. We generated transgenic potato lines containing the StWAKL2 promoter fused to a reporter gene and used the lines to evaluate StWAKL2 expression during potato development and upon nematode infection. StWAKL2 displayed specific expression patterns in potato plant. Most importantly, StWAKL2 was dramatically down-regulated at nematode infection sites on potato roots. The results indicated that suppressing the activity of WAK/WAKL regulators may be crucial for cyst nematodes to establish successful infection of host plants. A better understanding of the involvement of the WAK/WAKL family in nematode parasitism may suggest new strategies for nematode control.

Technical Abstract: Plant cell wall associated kinases (WAKs) and WAK-like kinases (WAKLs) have been increasingly recognized as important regulators of plant immunity against various plant pathogens. However, a role of the WAK/WAKL family in plant-nematode interactions remains to be revealed. Here, we have analyzed a WAK-encoding gene (Soltu.DM.02G029720.1) from potato (Solanum tuberosum). The Soltu.DM.02G029720.1 encoded protein contains domains characteristic of WAK/WAKL proteins and shows the highest similarity to SlWAKL2 from tomato, we thus named the gene as StWAKL2. Phylogenetic analysis of a wide range of plant WAKs/WAKLs further revealed a close similarity of StWAKL2 with two WAKs that were demonstrated having a role in disease resistance. To gain insights into the potential regulation and function of StWAKL2, transgenic potato lines containing the StWAKL2 promoter fused to the ß-glucuronidase (GUS) reporter gene were generated and used to investigate StWAKL2 expression during plant development and upon nematode infection. Histochemical analyses revealed that StWAKL2 has specific expression patterns in potato leaf and root tissues. During nematode infection, GUS activity was mostly not detected at nematode infection sites over the course of nematode parasitism, although strong GUS activity was observed in root tissues adjacent to the infection region. Furthermore, mining of the transcriptome of cyst nematode-induced feeding cells in roots of Arabidopsis identified a few WAK/WAKL genes, including a StWAKL2 homologue, to be significantly down-regulated. These results indicated that specific suppression of WAK/WAKL genes in nematode-induced feeding sites is crucial for cyst nematode to achieve successful infection of host plants. Further studies are needed to uncover a role of WAK/WAKL genes in plant defenses against nematode infection.