ABSTRACT Due to climate change, the requirement for increased resilience by grassland systems to onsets of ever‐increasing drought stresses makes the development of drought‐resistant forage crops a priority for future food and energy security. Novel × Festulolium ( Festuca × Lolium ) cultivars offer unique opportunities to combine complementary traits from both genera, delivering agronomic and ecosystem benefits in sustainable grassland systems. Here, we present a cytological and drought‐resistance assessment of × Festulolium cultivar “AberRoot” ( L. perenne × F. mairei ), an elite cultivar on the UK National Recommended Grass and Clover List. We show that successive breeding generations lead to progressive elimination of most F. mairei chromosomes, whilst terminal F. mairei introgressions were retained in 76.7% of genotypes, with up to eight introgressions detected on six L. perenne chromosomes. Genotypes that carried F. mairei introgressions exhibited substantially lower mortality under drought (11.1%–14.8%) compared with non‐introgressed lines and the L. perenne cultivar used as control (29.6%–35.7%). GAMM analysis revealed a significant interaction between the genomic group and the experimental phase ( χ 2 = 14.29, p = 0.027), confirming that introgressed genotypes maintained superior growth trajectories during stress and recovered more rapidly upon re‐watering. Most notably, over 46% of genotypes that carried a F. mairei introgression on the short arm of L. perenne chromosome 3 were associated with grasses with the most statistically robust drought resistance response ( p < 0.001 during Recovery). This finding is consistent with previous evidence linking chromosome 3 in Festuca species to drought tolerance, water‐use efficiency, and deep rooting. These results demonstrate, using a high‐performing cultivar, how a strategy of targeted chromosomal introgression of genes for drought resistance sourced from related stress‐tolerant grass species can provide novel and stable adaptive variation without compromise to agronomic performance. The outcomes provide a practical framework for the breeding of climate‐resilient forage grasses.
Kopecký et al. (Fri,) studied this question.