Sex-specific adaptive strategies and rhizosphere microbiome responses to drought stress in Bouteloua dactyloides
摘要
Drought is becoming more frequent and severe under global climate change. Bouteloua dactyloides (Nutt.) (hereafter, B. dactyloides) is a dioecious, drought-tolerant warm-season turfgrass, but whether males and females use different adaptive strategies under drought remains unclear. We conducted a pot experiment to compare male and female plants under well-watered (90% field capacity) and drought-stressed (30% field capacity) conditions. We hypothesized that male and female B. dactyloides plants would exhibit sex-specific adaptive strategies in physiological traits and rhizosphere microbial communities under drought stress. Drought increased malondialdehyde and proline contents and enhanced superoxide dismutase and ascorbate peroxidase activities in both sexes, while peroxidase activity decreased. Under well-watered conditions, females had a higher drought resistance index than males, whereas no significant sex difference was detected under drought. Sex-specific responses were still evident; females showed a higher root-shoot ratio, whereas males exhibited increased catalase (CAT) activity. Drought and plant sex also jointly altered rhizosphere microbial communities. Drought increased fungal alpha diversity only in males, whose rhizospheres were enriched in Basidiomycota and Glomeromycota. Drought suppressed bacterial aerobic metabolism and sulfur respiration functions, as well as saprotrophic and pathogenic fungi in both sexes. Notably, male rhizospheres were significantly enriched in symbiotic fungi, particularly arbuscular mycorrhizal fungi (AMF). Overall, female B. dactyloides mainly enhances drought adaptation through morphological plasticity, whereas males rely more on a microbiome-mediated strategy centered on AMF recruitment. These findings reveal sex-specific physiological and rhizosphere microbiome adaptation pathways and underscore the role of the microbiome in drought response, providing a basis for cultivar selection in arid-region turf management.