Histopathological Investigation of Varietal Responses to Cercospora beticola Infection Process on Sugar Beet Leaves

Md Ziaur Rahman Bhuiyan, Shyam Solanki, Luis E del Rio Mendoza, Pawel Borowicz, Dilip K. Lakshman, Aiming Qi, Gazala Ameen, Mohamed F. R. Khan

Research output: Contribution to journalArticlepeer-review


Cercospora leaf spot (CLS) is the most destructive foliar disease in sugar beet (Beta vulgaris). It is caused by Cercospora beticola Sacc., a fungal pathogen that produces toxins and enzymes which affect membrane permeability and cause cell death during infection. In spite of its importance, little is known about the initial stages of leaf infection by C. beticola. Therefore, we investigated the progression of C. beticola on leaf tissues of a susceptible and resistant sugar beet varieties at 12 h intervals during the first five days after inoculation using confocal microscopy. Inoculated leaf samples were collected, and stored in DAB (3,3'-Diaminobenzidine) solution until processed. Samples were stained with Alexa Fluor 488 dye to visualize fungal structures. Fungal biomass accumulation, reactive oxygen species (ROS) production, and the area under disease progress curve were evaluated and compared. ROS production was not detected on any variety before 36 hours post inoculation (hpi). C. beticola biomass accumulation, percentage leaf cell death and disease severity were all significantly greater in the susceptible variety compared to the resistant variety (P<0.05). Conidia penetrated directly through stomata between 48- to 60-hpi and produced appressoria on stomatal guard cells at 60- to 72-hpi in susceptible and resistant varieties, respectively. Penetration of hyphae inside the parenchymatous tissues varied in accordance with time post-inoculation and varietal genotypes. Overall, this study provides a detailed account to date of events leading to CLS disease development in two contrasting varieties.
Original languageEnglish
JournalPlant Disease
Early online date17 Jun 2023
Publication statusE-pub ahead of print - 17 Jun 2023


  • hemi-biotrophic
  • infection mechanism
  • confocal microscopy
  • sugar beet


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