Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Deficiency of ChPks and ChThr1 Inhibited DHN-melanin Biosysthesis, Disrupted Cell Wall Integrity and Attenuated Pathogenicity in Colletotrichum higginsianum

Version 1 : Received: 3 October 2023 / Approved: 3 October 2023 / Online: 4 October 2023 (07:40:06 CEST)

A peer-reviewed article of this Preprint also exists.

Duan, L.; Wang, L.; Chen, W.; He, Z.; Zhou, E.; Zhu, Y. Deficiency of ChPks and ChThr1 Inhibited DHN-Melanin Biosynthesis, Disrupted Cell Wall Integrity and Attenuated Pathogenicity in Colletotrichum higginsianum. Int. J. Mol. Sci. 2023, 24, 15890. Duan, L.; Wang, L.; Chen, W.; He, Z.; Zhou, E.; Zhu, Y. Deficiency of ChPks and ChThr1 Inhibited DHN-Melanin Biosynthesis, Disrupted Cell Wall Integrity and Attenuated Pathogenicity in Colletotrichum higginsianum. Int. J. Mol. Sci. 2023, 24, 15890.

Abstract

Colletotrichum higginsianum is a major pathogen causing anthracnose in Chinese flowering cabbage (Brassica parachinensis), posing a significant threat to the Chinese flowering cabbage industry. The conidia of C. higginsianum germinate and form melanized infection structures called appressoria, which enable penetration of the host plant's epidermal cells. However, the molecular mechanism underlying melanin biosynthesis in C. higginsianum remains poorly understood. In this study, we identified two enzymes related to DHN-melanin biosynthesis in C. higginsianum: ChPks and ChThr1. Our results demonstrate that the expression levels of genes ChPKS and ChTHR1 were significantly up-regulated during hyphal and appressorial melanization processes. Furthermore, knockout of the gene ChPKS resulted in a blocked DHN-melanin biosynthetic pathway in hyphae and appressoria, leading to increased sensitivity of the ChpksΔ mutant to cell wall interfering agents as well as decreased turgor pressure and pathogenicity. It should be noted that although the Chthr1Δ mutant still exhibited melanin accumulation in colonies and appressoria, its sensitivity to cell wall interfering agents and turgor pressure decreased compared to wild-type strains; however, complete loss of pathogenicity was not observed. In conclusion, our results indicate that DHN-melanin plays an essential role in both pathogenicity and cell wall integrity in C. higginsianum. Specifically, ChPks is crucial for DHN-melanin biosynthesis while deficiency of ChThr1 does not completely blocked melanin production.

Keywords

Colletotrichum higginsianum; DHN-melanin; polyketide synthase (Pks); trihydroxynaphthalene reductase (Thr1); pathogenicity

Subject

Biology and Life Sciences, Biochemistry and Molecular Biology

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