Diverse plant biotrophs that establish a sustained site of nutrient acquisition induce localized host endoreduplication. Endoreduplication is a process by which cells successively replicate their genomes without mitosis, resulting in an increase in nuclear DNA ploidy. Elevated ploidy is associated with enhanced cell size, metabolic capacity, and the capacity to differentiate. Localized host endoreduplication induced by adapted plant biotrophs promotes biotroph colonization, development, and/or proliferation. When induced host endoreduplication is limited, biotroph growth and/or development are compromised. Herein, we examine a diverse set of plant-biotroph interactions to identify (a) common host components manipulated to promote induced host endoreduplication and (b) biotroph effectors that facilitate this induced host process. Shared mechanisms to promote host endoreduplication and development of nutrient exchange/feeding sites include manipulation centered on endocycle entry at the G2-M transition as well as yet undefined roles for differentiation regulators (e.g., CLE peptides) and pectin/cell wall modification.
Keywords: biotroph; cell cycle; effector; endoreduplication; ploidy.