Long-term effect of niclosamide on inhibition of bacterial leaf blight in rice

Abstract

Bacterial leaf blight is one of the major diseases in rice and affects yields. Thus, various methods have been applied to protect rice from this disease. Here, we show systemic translocation of the human drug niclosamide (5-chloro-N-(2-chloro-4-nitrophenyl)- 2-hydroxybenzamide) in rice and its long-term effect on prevention of rice leaf blight. The development of Xanthomonas oryzae pv. oryzae-induced rice leaf blight was effectively inhibited in untreated systemic leaves as in niclosamide-treated leaves, although its effect gradually decreased in a time-dependent manner. Time-course examination after niclosamide treatment showed that the niclosamide level was highest after 3 h in non-treated distal leaves, suggesting fast systemic movement of niclosamide from the treated local site to untreated distal regions. Our data indicate that niclosamide controls rice leaf blight by its rapid systemic movement and that its effect is maintained for a long time.

Niclosamide Blocks Rice Leaf Blight by Inhibiting Biofilm Formation of Xanthomonas oryzae

“…Our in vivo experiment further demonstrated that niclosamide can effectively block the growth of Xoo thereby impeding the development of bacterial blight disease in rice plants ( Figures 1E,F ). This observation was consistent with the findings of Kim et al (2016a , b ) where they also showed that niclosamide has no harmful effect on the overall vegetative/reproductive growth and yield of the rice plant. In addition, they also showed that niclosamide can induce the expression of defense-related genes including salicylic and jasmonic acid hormones related genes in rice.…”

“…According to the earlier reports ( Kim et al, 2016a , b ), we first confirmed the antibacterial activity of niclosamide against two pathogenic Xanthomonas oryzae pv. oryzae strains PXO99 and GDIV corresponding to race 6 and race 4 respectively.…”

“…Although there are several genetic, biological, and chemical control approaches to enhance the rice protection from bacterial leaf blight, the quest for more effective and reliable approach that would provide large-scale protection is still the need of the hour. More than 30 drugs, including antibiotics, have been developed to safeguard crops from pathogen attack ( McManus et al, 2002 ; Xu et al, 2015 ; Kim et al, 2016a , b ; Liang et al, 2016 ; Rama Devi et al, 2016 ). Based on multiple experimental approaches like turbidity assay, XTT assay and microtitre plate readings here we showed that niclosamide has a strong inhibitory (>80%) potential against Xoo, and had no detrimental impact on the growth of E. coli ( Figure 1 ).…”

Pathogen-Induced Expression of OsDHODH1 Suggests Positive Regulation of Basal Defense Against Xanthomonas oryzae pv. oryzae in Rice

“…BLB is spread worldwide [22][23][24] and can cause as high as 60% reduction in rice yield in severe epidemics [16,23,25]. This vascular disease starts with the infection of rice leaves or roots by the Xoo bacterium through hydathodes (specialized pores present at the leaf margin where vascular supply ends), natural plant openings, such as stomata, and wounds [25][26][27]. Xoo multiplies and spreads within the xylem, causing long, grey to white opaque necrotic lesions that typically spread from the tip of a rice leaf [26,28].…”