CONCLUSIONS
Considering the fundamental role of root exudates in plant-soil
interactions, we investigated the impact of single abiotic stresses,
drought and heat, and their combination on the exudate profile of maize
plants. Significantly different exudate profiles could be observed in
presence of drought and heat stress, involving stress-specific up- and
down-exuded compounds. Most likely, these root exudate blends could play
a role in the plant acclimation processes induced by reduced water
availability or increased soil temperature. The combination of drought
and heat stress produced a different root exudate composition than
single stresses, thus strengthening the idea that multiple stresses can
interfere with plant processes in a non-additive way.
Taken together, our results highlight that root exudates are a pivotal
process through which maize plants manage their rhizosphere processes in
response to abiotic stresses, with distinctive traits being observed
when maize plants were exposed to the combined stress. This fine tuning
is also mechanistically linked to changes in soil microbial community
composition and functioning. These new insights in rhizosphere processes
could be useful to evaluate and define future mitigation strategies
aimed at limiting the impact of drought and heatwaves on maize growth
and productivity.