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Zhang B, Zhang N, Li R, Fu Z, Sun Y, Ren Z, Mu F, Han Y, Han Y. Underlying Mechanisms of the Hedgehog-Like Panicle and Filamentous Leaf Tissue Symptoms Caused by Sclerospora graminicola in Foxtail Millet. PHYTOPATHOLOGY 2024; 114:73-83. [PMID: 37535821 DOI: 10.1094/phyto-03-23-0097-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
Downy mildew caused by Sclerospora graminicola is a systemic infectious disease affecting foxtail millet production in Africa and Asia. S. graminicola-infected leaves could be decomposed to a state where only the veins remain, resulting in a filamentous leaf tissue symptom. The aim of the present study was to investigate how S. graminicola influences the formation of the filamentous leaf tissue symptoms in hosts at the morphological and molecular levels. We discovered that vegetative hyphae expanded rapidly, with high biomass accumulated at the early stages of S. graminicola infection. In addition, S. graminicola could affect spikelet morphological development at the panicle branch differentiation stage to the pistil and stamen differentiation stage by interfering with hormones and nutrient metabolism in the host, resulting in hedgehog-like panicle symptoms. S. graminicola could acquire high amounts of nutrients from host tissues through secretion of β-glucosidase, endoglucanase, and pectic enzyme, and destroyed host mesophyll cells by mechanical pressure caused by rapid expansion of hyphae. At the later stages, S. graminicola could rapidly complete sexual reproduction through tryptophan, fatty acid, starch, and sucrose metabolism and subsequently produce numerous oospores. Oospore proliferation and development further damage host leaves via mechanical pressure, resulting in a large number of degraded and extinct mesophyll cells and, subsequently, malformed leaves with only veins left, that is, "filamentous leaf tissue." Our study revealed the S. graminicola expansion characteristics from its asexual to sexual development stages, and the potential mechanisms via which the destructive effects of S. graminicola on hosts occur at different growth stages.
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Affiliation(s)
- Baojun Zhang
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
- Shanxi Key Laboratory of Minor Crops Germplasm Innovation and Molecular Breeding, Taiyuan, 030000, China
| | - Nuo Zhang
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
- Shanxi Key Laboratory of Minor Crops Germplasm Innovation and Molecular Breeding, Taiyuan, 030000, China
| | - Renjian Li
- College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430000, China
| | - Zhenxin Fu
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
- Shanxi Key Laboratory of Minor Crops Germplasm Innovation and Molecular Breeding, Taiyuan, 030000, China
| | - Yurong Sun
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
- Shanxi Key Laboratory of Minor Crops Germplasm Innovation and Molecular Breeding, Taiyuan, 030000, China
| | - Zhixian Ren
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
- Shanxi Key Laboratory of Minor Crops Germplasm Innovation and Molecular Breeding, Taiyuan, 030000, China
| | - Fan Mu
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
| | - Yuanhuai Han
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
- Shanxi Key Laboratory of Minor Crops Germplasm Innovation and Molecular Breeding, Taiyuan, 030000, China
| | - Yanqing Han
- College of Plant Protection, Shanxi Agricultural University, Taigu, 030801, China
- Shanxi Key Laboratory of Minor Crops Germplasm Innovation and Molecular Breeding, Taiyuan, 030000, China
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