C3-species Calotropis procera increase specific leaf area and decrease stomatal pore size, alleviating gas exchange under drought and salinity

Plants have developed several strategies, some of which are anatomical, to cope with stressful environmental conditions, such as drought and salinity. At the leaf anatomical level, these strategies are mostly related to photosynthesis and, therefore, to the physiological performance of plants. Thus, the ability to adjust leaf traits during stress can be an important strategy to tolerance. Calotropis procera is distinct for its robust performance under drought and salinity; hence, our main goal was to verify whether and what this species changes leaf anatomical attributes during stressful conditions, and how this may help its performance. Two controlled experiments were conducted, under drought and salinity, the anatomical and physiological parameters of C. procera, such as gas exchanges, water status, stomata, trichrome, cuticle and mesophyll, were measured over 46 and 56 days, respectively. Plants had adjustments in leaf attributes under both conditions. Under drought, on the sixth day, plants showed thicker mesophyll, and at ninth increased cuticle thickness and stomata and trichome density (at 18th). Under salinity conditions, the plants adjusted the same attributes (22nd day). Such adjustments are mainly involved in reducing water loss, which improves water status in plants and the efficient use. In turn, water efficient use promotes direct and indirect improvements in photosynthetic rate under stress, possibly by increasing sites to uptake CO2 and optimizing diffusion. Our findings showed that C. procera has anatomical plasticity, changing traits that can play a decisive role in its physiological adaptation, giving advantage mainly to its efficient stomatal control under water-limited environmental conditions.

Automated summary

Plants have developed strategies, including anatomical adjustments, to cope with stressful environmental conditions like drought and salinity. Calotropis procera, known for its robust performance under such stress, changes leaf attributes to reduce water loss and improve water use efficiency, ultimately enhancing photosynthetic rate. This anatomical plasticity contributes to the plant's physiological adaptation and efficient stomatal control under water-limited conditions.