Covering cabbage leaves with cellulose nanofiber confers resistance against Pseudomonas cannabina pv. alisalensis

Cellulose nanofiber (CNF) is produced from cellulose, which is one of the most abundant and renewable biomasses in nature. We previously demonstrated that covering soybean leaves with CNF changed leaf surface hydrophobicity and confers resistance against Phakopsora pachyrhizi , causal fungi of Asian soybean rust. However, whether CNF also suppresses bacterial disease has not been investigated. Therefore, we here investigated CNF application on management of bacterial blight disease caused by Pseudomonas cannabina pv. alisalensis ( Pcal ), which is one of the problematic bacterial diseases. CNF-treated leaves showed reduced disease symptoms and bacterial populations after spray-inoculation, but not after syringe-inoculation. These results indicate that covering cabbage leaves with CNF confers resistance before Pcal enters plants. We also demonstrated that bacterial virulence-related genes, including type three effectors-encoding, coronatine biosynthesis, and flagellin-related genes, were down-regulated on the CNF-treated leaf surfaces. Moreover, bacterial entry on CNF-treated leaves was significantly reduced. We also showed that flagellin (FliC) contributes to motility, bacterial entry, and disease development during Pcal infection. These results indicate that covering with CNF decreases flagellar motility and bacterial entry, leading to reduction of disease development. Thus, altering the leaf surface properties can change bacterial behaviors. Together, CNF has a potential to be a novel and efficient agent for controlling bacterial disease.