Stronger drought tolerance in C4 compared to C3 grass crops is achieved via both avoidance and resistant strategies

Authors: BOISSEAUX, MARION - California State University; NADAL, MIQUEL - Inrae; ALBUQUERQUE, CAETANO - California State University; GOMEZ, JESSE - California State University; AMITRANO, CHIARA - California State University; McElrone, Andrew; SACK, LAWREN - University Of California (UCLA); SCOFFONI, CHRISTINE - California State University

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: This study reveals the three studied C4 grasses are better adapted to drought compared to the three C3 species by displaying both drought avoidance and tolerance strategies. During the initial stages of dehydration, C4 grasses (including corn) avoid drought via a dynamic response of gas exchange and greater water-use efficiency compared to C3 grasses (including oats, barley, and wheat). During more severe drought-induced dehydration, C4 grasses show greater tolerance than C3 via higher embolism resistance and resilience in photochemistry.

Technical Abstract: Grasses comprise many of the world’s major cereal crops, yet the physiological mechanisms underlying their resilience to environmental stress remain unclear. While C4 grasses tend to display higher water-use-efficiency than C3 grasses, little is known about the underlying physiological and structural dynamics during mild and severe dehydration. We explored the sequence of decline with dehydration in leaf, root and whole plant hydraulic functions, and in leaf gas exchange and photochemistry (Fv/Fm) across three C3 and three C4 grass crops, along with their rehydration capacity post dehydration. We observed distinct strategies between C3 and C4 species in response to water stress. C4 species were more sensitive in their gas exchange response at early stages of dehydration than C3 species, and more tolerant to damages in photosystem II and embolism under severe dehydration. The higher resistance to severe dehydration in C4 species was accompanied by a greater ability to recover in photochemical yield of photosystem II compared to C3 species. These functional differences were associated with contrasting cell-level properties: C4 species had higher leaf capacitance, less negative turgor loss point and experienced greater leaf shrinkage than C3 species. Our findings reveal that leaf structure-function shape drought-response strategies in C3 and C4 species, contributing to a broader understanding of how different photosynthetic pathways influence plant performance under stress.