The Silencing of the StPAM16-1 Gene Enhanced the Resistance of Potato Plants to the Phytotoxin Thaxtomin A

Potato common scab (CS) caused by <i>Streptomyces scabiei</i> is a severe disease that threatens tuber quality and its market value. To date, little is known about the mechanism regulating the resistance of potato to CS. In this study, we identified a presequence translocase-associated motor 16 gene from potato (designated <i>StPAM16-1</i>) that is involved in the response to the phytotoxin thaxtomin A (TA) secreted by <i>S. scabiei</i>. The StPAM16-1 protein was localized in the mitochondria, and the expression of the gene was upregulated in potato leaves treated with TA. The suppression of <i>StPAM16-1</i> in potato led to enhanced resistance to TA and <i>S. scabiei</i>. Protein interaction analyses revealed that StPAM16-1 interacted with the subunit 5b of the COP9 signalosome complex (StCSN5). Similar to that of <i>StPAM16-1</i>, the expression levels of <i>StCSN5</i> significantly increased in potato leaves treated with TA. These results indicated that StPAM16-1 acted as a negative regulator and was functionally associated with StCSN5 in the immune response of potato plants against CS. Our study sheds light on the molecular mechanism by which PAM16 participates in the plant immune response. Furthermore, both <i>StPAM16-1</i> and <i>StCSN5</i> could be potential target genes in the molecular breeding of potato cultivars with increased resistance to CS.