2026/01/21 by Cheng-Yu Tsai, Chih-Li Wang · 1 voice
Biochemistry, Genetics and Molecular Biology · Agricultural and Biological Sciences · #Fungal and yeast genetics research #Plant Gene Expression Analysis #Plant-Microbe Interactions and Immunity
paper · doi:10.1094/phyto-08-25-0279-r
openalex publication_date 2026/01/21 · openalex created_date 2026/01/22 · openalex updated_date 2026/07/02
Fusarium oxysporum f. sp. conglutinans, F. oxysporum f. sp. rapae, F. oxysporum f. sp. raphani, and F. oxysporum f. sp. matthiolae can cause yellows disease of economically important species in the Brassicaceae family. Among these, F. oxysporum f. sp. rapae induces yellows in leaf mustard and Chinese cabbage. SGE1 (secreted-in-xylem [SIX] gene expression 1) is a transcription factor characterized by the presence of the WOPR box domain. Homologs of SGE1 in other Fusarium species play a crucial role in virulence and regulate the expression of SIX effector genes. However, the role of the SGE1 homolog in F. oxysporum f. sp. rapae ( FoRP-SGE1) in pathogenesis and fungal development remains unexplored. To investigate its function in regulating pathogenicity and fungal development, gene knockout mutants of FoRP-SGE1 (Δ FoRP-SGE1) were generated and validated. Δ FoRP-SGE1 showed a reduction in conidiation but normal colony growth and conidial germination. Notably, Δ FoRP-SGE1 completely lost pathogenicity in both leaf mustard and Arabidopsis thaliana, but it retained the ability to colonize leaf mustard plants, indicating that FoRP-SGE1 is a key pathogenicity factor. Expression of SIX9 and SIX14 was significantly diminished in Δ FoRP-SGE1. Furthermore, most chlamydospores of Δ FoRP-SGE1 lacked the outermost fibrillose coat. Germination of Δ FoRP-SGE1 chlamydospores was also impaired under various stress conditions, including osmotic stress, drought, UV exposure, and fluazinam toxicity. This study presents, for the first time, the role of a Fusarium SGE1 homolog in the morphology and persistence of chlamydospores. Collectively, our findings suggest that FoRP-SGE1 is a critical pathogenicity factor in the leaf mustard– F. oxysporum f. sp. rapae and Arabidopsis– F. oxysporum f. sp. rapae pathosystems and is involved in the development of the fibrillose coat of chlamydospores and their resistance to environmental stresses.