Polyploidy drives changes in tissue allocation modifying whole-plant water relations.

This article investigates how polyploidy—defined as organisms possessing more than two full chromosome sets due to whole-genome duplication (WGD)—affects whole-plant water relations in the Dianthus broteri species complex, which includes diploid (2×), low polyploid (4×, 6×), and high polyploid (12×) cytotypes. The study demonstrates that increasing ploidy correlates with altered tissue allocation, specifically a shift from leaf to root and xylem investment, resulting in enhanced root-to-stem hydraulic conductance (Kr-s) and stomatal conductance (gc), while maintaining coordinated stomatal responses to leaf-to-air vapor pressure deficit (VPDL) across ploidies. High polyploids (12×) exhibit a water-use strategy characterized by greater hydraulic capacity and tighter water potential regulation but incur higher xylem construction costs relative to water transport, suggesting a trade-off that may confer advantages under water-limited conditions typical of their xeric habitats. These findings highlight that multiple rounds of genome duplication induce substantial, tissue-specific physiological and morphological changes influencing plant water uptake, transport, and gas exchange, thereby potentially shaping ecological adaptation and fitness in varying environments.