Cell division and specification are crucial for plant development and coping with diverse environmental cues. Most land plants rely on symbiosis with arbuscular mycorrhizal (AM) fungi to cope with soil nutrient limitations by forming arbuscules in root inner cortex cells. What determines the AM susceptibility of these inner cortex cells is currently unknown. Here we show that DELLA transcriptional regulators control the number of inner cortex cells with an AM-susceptible identity at the root stem cell niche of Medicago truncatula in a dose-dependent manner. Genetic analyses suggest that this activity converges with the well-known mobile SHORT-ROOT transcription factor regulating ground tissue development. Furthermore, we show that MtDELLA1 protein moves from the stele/endodermis to the cortex in the mature part of the root to facilitate arbuscule formation. We propose that the formation of a root inner cortex cell identity controlled by mobile DELLA and SHORT-ROOT is a fundamental basis for AM symbiosis.

Humans are driving biodiversity change, which also alters community functional traits. However, how changes in the functional traits of the community alter ecosystem functions—especially belowground...

Call for Symposia The Call for Symposia at ICOM2026 is open! Download Application Form below Deadline for submission: 15 October 2025 Decision: 1 November 2025 ICOM2026 will host a series of sympos…

Call for Symposia The Call for Symposia at ICOM2026 is open! Download Application Form below Deadline for submission: 15 October 2025 Decision: 1 November 2025 ICOM2026 will host a series of sympos…

Native mycorrhizal fungi enhance prairie restoration by boosting native plant diversity, supporting late-successional species, and reducing invasive plants