Sechium edule (Cucurbitaceae), commonly known as chayote, which is a cucurbit of economic relevance, has experienced higher incidence of wilting from Phytophthora capsici in Mexican commercial fields during heavy rainfall. The infection process of this oomycete on chayote stems at the anatomical level had not been documented. This study characterized histological changes in chayote stems infected with P. capsici. Plants were inoculated at the stem base with P. capsici mycelial plugs, while controls received sterile plugs. Stem samples collected at 8, 12, 16, 22, and 30 days post-inoculation were processed and stained using safranin O–fast green. Microscopic observations showed progressive anatomical alterations. At 8 dpi, hyphae appeared in cortical parenchyma and epidermis, with phenolic compound accumulation. By 12 dpi, stromata and sporangia were visible in vascular and cortical tissues, with tyloses formation. At 16 dpi, cell wall collapse and xylem colonization became evident. These effects intensified at 22 and 30 dpi, with tissue degradation and an abundance of hyphae. Control stems maintained intact structures. Macroscopically, plants remained asymptomatic until 12 dpi, when brown lesions appeared. By 22 dpi, leaf yellowing and stem necrosis were observed, leading to plant death by 30 dpi. The results demonstrate the rapid colonization of chayote tissues by P. capsici, and its impact on vascular integrity. This study provides knowledge for future research on host resistance and disease management in chayote crops.
Olguín-Hernández et al. (Sun,) studied this question.
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