hemibiotrophy

Hemibiotrophy is a lifestyle observed in some plant pathogens in which infection unfolds in two distinct phases. The initial biotrophic phase involves colonization of living host tissue with little or no immediate tissue loss, allowing sustained nutrient uptake while the host remains viable. This is followed by a necrotrophic phase in which the pathogen kills host cells and feeds on the resulting dead material.

During biotrophy, pathogens often form specialized feeding structures such as haustoria or intracellular hyphae to obtain nutrients and to suppress or evade host defenses. The transition to necrotrophy is typically marked by a shift in gene expression, the production of cell-wall-degrading enzymes and toxins, and the induction of host cell death, enabling rapid tissue colonization. The timing of this switch varies among species, strains, host genotypes, and environmental conditions.

Hemibiotrophy is common among fungal and oomycete plant pathogens. Notable examples include Phytophthora infestans, Magnaporthe oryzae, and various Colletotrichum species. In many cases the biotrophic phase is relatively short, but the duration can differ depending on the interaction and external factors.

Understanding hemibiotrophy informs disease management and plant breeding. Strategies that limit initial biotrophic colonization, together with approaches to reduce subsequent tissue death, can decrease disease impact. Diagnosis relies on observing progressive symptom development, microscopic examination of feeding structures and lesions, and molecular markers tied to phase-specific gene expression.