Guobing Cui

Flavonoids are polyphenolic secondary metabolites that function as signaling molecules, allopathic compounds, phytoalexins, detoxifying agents and antimicrobial defensive compounds in plants. Blast caused by the fungusMagnaporthe oryzaeis a serious disease affecting rice cultivation. In this study, we revealed that a natural flavonoid, tangeretin, substantially delays the formation ofM. oryzaeappressoria and blocks the development of blast lesions on rice plants. Our data suggest that tangeretin has antioxidant activity that interferes with conidial cell death/ferroptosis, which is critical forM. oryzaepathogenicity. Tangeretin showed a ferroptosis inhibition efficacy comparable to the well‐established liproxstatin‐1. Furthermore, overexpression of the NADPH oxidasesNOX1orNOX2significantly decreased sensitivity toward tangeretin treatment, suggesting Nox‐mediated lipid peroxidation as a possible target for tangeretin in regulating redox signaling and ferroptosis inM. oryzae. Our nursery and field tests showed that application of tangeretin can effectively mitigate overall disease symptoms and prevent leaf blast. Our study reveals the plant‐derived fungal ferroptosis inhibitor tangeretin as a potential and novel antifungal agrochemical for the sustainable prevention of the devastating blast disease in important cereal crops.

In this study, we isolated an endophytic Burkholderia gladioli strain, named CGB10, from sugarcane leaves. B. gladioli CGB10 displayed strong inhibitory activity against filamentous growth of fungal pathogens, one of which is Sporisorium scitamineum that causes sugarcane smut, a major disease affecting the quality and production of sugarcane in tropical and subtropical regions. CGB10 could effectively suppress sugarcane smut under field conditions, without itself causing any obvious damage or disease, thus underscoring a great potential as a biocontrol agent (BCA) for the management of sugarcane smut. A toxoflavin biosynthesis and transport gene cluster potentially responsible for such antifungal activity was identified in the CGB10 genome. Additionally, a quorum-sensing gene cluster was identified too and compared with two close Burkholderia species, thus supporting an overall connection to the regulation of toxoflavin synthesis therein. Overall, this work describes the in vitro and field Sporisorium scitamineum biocontrol by a new B. gladioli strain, and reports genes and molecular mechanisms potentially involved.