Aegilops geniculata Roth: Biology, Ecology and Potential Applications in Crop Breeding and Nature-Based Solutions

Aegilops geniculata Roth is a tetraploid wild relative of wheat distributed throughout the Mediterranean Basin, where it grows in a wide range of habitats. Due to its genetic diversity, ecological plasticity and adaptation to Mediterranean ruderal environments, the species has attracted increasing interest as a genetic resource for wheat improvement and as a potential component of sustainable agroecosystems. Beyond use in agriculture, its ecological characteristics also suggest applications in Nature-based Solutions, including revegetation of degraded, low-input, semi-arid ecosystems. This review aims to provide a comprehensive synthesis of current knowledge on the taxonomy, genetics, morphology, distribution, ecology, reproductive biology and conservation of Ae. geniculata. This work is complemented by original experimental data on agronomic traits and an assessment of ex situ conservation efforts. Evidence highlights the species’ value as a source of drought- and stress-adaptive traits for wheat improvement, plus promising cover crop traits (rapid establishment, stable biomass production and flexible germination behavior). Remaining knowledge gaps include population genomics, conservation of undercollected populations and field-scale agronomic performance to better clarify the potential of this species as a cover crop. This work supports further investigation of Ae. geniculata as both a valuable crop wild relative and a promising cover crop for Mediterranean agroecosystems.