Global Regulatory Role of the Myb-like Transcription Factor MylA in Aspergillus flavus

The major aflatoxin producer Aspergillus flavus reproduces through asexual reproduction, producing the asexual spore called conidia and the process of conidia formation (conidiation) is regulated by various transcription factors. In this study, we characterized the role of Myb-like protein A, MylA, in A. flavus. Disruption of mylA resulted in reduced conidia production and colony growth compared to the control. Moreover, the ∆mylA conidia exhibited a defect in trehalose biosynthesis, leading to decreased spore viability and thermal stress tolerance, as trehalose functions as a cell protectant in fungi. The ΔmylA strain also showed increased sensitivity to cell wall-disturbing agents and oxidative stress, suggesting a role for MylA in maintaining cell wall integrity and oxidative stress resistance. In addition, the ∆mylA conidia displayed a delayed germination rate and reduced germ tube elongation compared to the control. To assess its role in plant pathogenicity, a kernel bioassay was conducted. The ΔmylA strain exhibited reduced conidia colonization, spore viability and aflatoxin production, when infected to kernels. Collectively, our findings demonstrate that MylA is a critical regulator of fungal development, stress responses, and plant pathogenicity in A. flavus.