China
July 19, 2022
The bacterial leaf blight disease (BLB) is among the three most devastating pathogens limiting rice production in China. Recent years has witnessed a resurgence of BLB in Zhejiang and other major rice areas in China due to climate change and the changes in the cultivation system. Moreover, there has emerged a new epidemic pattern. These have posed great challenges to the control of BLB. As one of the ten emerging chemical technologies that will change the world in the future, nano-enabled agrochemicals are currently being applied to the prevention and control of BLB in Zhejiang Province. Therefore, there is an urgent need to unravel the mechanism of these agrochemicals in the field, thus providing theoretical guidance for the future use of nanomaterials for the control of rice bacterial diseases.
The research team led by Prof. LI Bin from the Zhejiang University College of Agriculture and Biotechnology published an open-access research article entitled “Bioengineered chitosan-iron nanocomposite controls bacterial leaf blight disease by modulating plant defense response and nutritional status of rice (Oryza sativa L.)” in the journal Nano Today on July 6.
Graphical Abstract
In previous research, LI Bin et al. identified the role of nanomaterials in guarding against abiotic stresses (Journal of Hazards Materials, 2022) and summarized their application prospects in rice production (Critical Reviews in Food Science and Nutrition, 2022). On this basis, LI Bin et al. carried out the bioengineering of chitosan-iron nanocomposites (BNCs) along with the in vitro and in vivo assessment of BNCs bactericidal activity against Xanthomonas oryzae pv. oryzae (Xoo), which causes BLB. In addition, they evaluated the impact of BNCs on the endophytic microbiome of healthy and BLB-infected rice and analyzed BNCs’ internal mechanism for reducing the harm of BLB.
Their study revealed that BNCs could inhibit the activity of Xoo in direct or indirect ways. First, the interaction between BNCs and bacteria induced the controlled release of Fe2+ ions, resulting in cell membrane disruption, ROS formation, DNA damage, denaturation of proteins and enzymes, and leakage of intracellular contents that could ultimately lead to the death of Xoo cells. Second, BNCs could enter leaves through the stomata and disperse within the large air spaces of spongy mesophyll cells. Hence, the in planta accumulation of BNCs could reprogram normal rice growth by triggering the SA signaling pathway and the defense mechanism of antioxidants, improving the photosynthetic profile and nutrient acquisition, and maintaining ionic homeostasis, which could ultimately scavenge the ROS and relieve rice plants from cellular oxidative stresses.
In addition, high-throughput sequencing data revealed that BNCs could significantly reduce the relative abundance of Xoo in rice plants by reshaping the phyllospheric and root-endophytic bacterial community of rice and increase the diversity of the bacterial community in healthy and diseased plants.
These findings demonstrated that BNCs have enormous potential to serve as a non-toxic, sustainable and highly-efficient alternative in terms of plant disease management.
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