Ferric Chloride Controls Citrus Anthracnose by Inducing the Autophagy Activity of Colletotrichum gloeosporioides

Yuqing Wang; Xiaoxiao Wu; Yongqing Lu; Huimin Fu; Shuqi Liu; Juan Zhao; Chaoan Long

doi:10.3390/jof9020230

Ferric Chloride Controls Citrus Anthracnose by Inducing the Autophagy Activity of Colletotrichum gloeosporioides

J Fungi (Basel). 2023 Feb 9;9(2):230. doi: 10.3390/jof9020230.

Authors

Yuqing Wang^{1

2

3

4

5}, Xiaoxiao Wu^{6

7

8}, Yongqing Lu^{1

2

3

4

5}, Huimin Fu^{6

7

8}, Shuqi Liu^{1

2

3

4

5}, Juan Zhao^{1

2

3

4

5}, Chaoan Long^{1

2

3

4

5}

Affiliations

¹ National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Wuhan 430070, China.
² Key Laboratory of Horticultural Plant Biology of Ministry of Education, Wuhan 430070, China.
³ National R&D Center for Citrus Preservation, Wuhan 430070, China.
⁴ National Centre of Citrus Breeding, Wuhan 430070, China.
⁵ College of Horticulture & Forestry Sciences of Huazhong Agricultural University, Wuhan 430070, China.
⁶ Guangxi Laboratory of Germplasm Innovation and Utilization of Specialty Commercial Crops in North Guangxi, Guilin 541004, China.
⁷ Guangxi Citrus Breeding and Cultivation Research Center of Engineering Technology, Guilin 541004, China.
⁸ Guangxi Academy of Specialty Crops, Guilin 541004, China.

Abstract

Colletotrichum gloeosporioides causes citrus anthracnose, which seriously endangers the pre-harvest production and post-harvest storage of citrus due to its devastating effects on fruit quality, shelf life, and profits. However, although some chemical agents have been proven to effectively control this plant disease, little to no efforts have been made to identify effective and safe anti-anthracnose alternatives. Therefore, this study assessed and verified the inhibitory effect of ferric chloride (FeCl₃) against C. gloeosporioides. Our findings demonstrated that FeCl₃ could effectively inhibit C. gloeosporioides spore germination. After FeCl₃ treatment, the germination rate of the spores in the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) groups decreased by 84.04% and 89.0%, respectively. Additionally, FeCl₃ could effectively inhibit the pathogenicity of C. gloeosporioides in vivo. Optical microscopy (OM) and scanning electron microscopy (SEM) analyses demonstrated the occurrence of wrinkled and atrophic mycelia. Moreover, FeCl₃ induced autophagosome formation in the test pathogen, as confirmed by transmission electron microscopy (TEM) and monodansylcadaverine (MDC) staining. Additionally, a positive correlation was identified between the FeCl₃ concentration and the damage rate of the fungal sporophyte cell membrane, as the staining rates of the control (untreated), 1/2 MIC, and MIC FeCl₃ treatment groups were 1.87%, 6.52%, and 18.15%, respectively. Furthermore, the ROS content in sporophyte cells increased by 3.6%, 29.27%, and 52.33% in the control, 1/2 MIC, and MIC FeCl₃ groups, respectively. Therefore, FeCl₃ could reduce the virulence and pathogenicity of C. gloeosporioides. Finally, FeCl₃-handled citrus fruit exhibited similar physiological qualities to water-handled fruit. The results show that FeCl₃ may prove to be a good substitute for the treatment of citrus anthracnose in the future.

Keywords: Colletotrichum gloeosporioides; ROS; autophagy; citrus; ferric chloride; membrane integrity.

Abstract

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