1 Introduction Ustilaginoidea virens, the causal agent of rice false smut, infects rice spikelets by initially colonising stamen filaments and then invading inner floral tissues to form characteristic false smut balls (Tang et al. 2013; Song et al. 2016). The disease has become one of the most serious threats to rice production in South and East Asia, causing substantial yield losses (Sun et al. 2020; Yang et al. 2023).