Gene expression in the smut fungus Ustilago esculenta governs swollen gall metamorphosis in Zizania latifolia

Abstract Ustilago esculenta, a smut fungus, can induce the formation of culm galls in Zizania latifolia, a vegetable consumed in many Asian countries. Specifically, the mycelia-teliospore (M-T) strain of U. esculenta induces the Jiaobai (JB) type of gall, while the teliospore (T) strain induces the Huijiao (HJ) type. The underlying molecular mechanism responsible for the formation of the two distinct types of gall remains unclear. Our results show that most differentially expressed genes relevant to effector proteins were up-regulated in the T strain compared to in the M-T strain during gall formation, and the expression of teliospore formation-related genes was higher in the T strain than in the M-T strain. Melanin biosynthesis was also clearly induced in the T strain. The T strain exhibits stronger pathogenicity and greater teliospore production than the M-T strain. We evaluated the implications of the gene regulatory networks in the development of these two types culm gall in Z. latifolia infected with U. esculenta and suggest potential targets for genetic manipulation to modify the gall type for this crop.