Biology subjects

Merilo, E.

Publications and source records attributed to Merilo, E..

3 recordsLinked to original sources

bioRxiv2025

Higher adaxial stomatal density is associated with lower grain yield in spring wheat

In land plants, stomatal pores on leaf surfaces developed to control gas exchange between leaf and surrounding air, but also to enable nutrient uptake and leaf cooling. Traits such as stomatal density (SD), guard cell size, stomatal distribution between the upper (adaxial) and lower (abaxial) leaf surfaces (stomatal ratio), and stomatal aperture width exhibit notable variation across different genotypes and environments. These traits influence leaf photosynthesis, water loss, growth, productivity, and pathogen susceptibility. Here, we studied different stomatal traits of spring wheat flag leaves and their relationship with grain yield in field experiments during 2022-2023. Significant genotypic variation among adaxial and abaxial SDs and stomatal ratios was detected, whereas stomatal conductance was mostly affected by annual differences in weather. A strong negative relationship between adaxial stomatal density and grain yield was detected under all conditions, when abiotic factors (water stress or nutrient limitation) resulted in yield losses, whereas under favourable conditions, there was no significant relationship between adaxial stomatal density and grain yield. The effects of leaf surface-specific traits on yield are often overlooked in physiological and breeding experiments. Our results indicate that higher-than-optimal adaxial SD values may result in wheat yield losses under stresses imposed by future climate conditions.

plant biology↗

bioRxiv2021

Concentration matters: different stomatal CO2-responses at sub-ambient and above-ambient CO2 levels

Stomatal pores that control plant CO2 uptake and water loss affect global carbon and water cycles. In the era of increasing atmospheric CO2 levels and vapor pressure deficit (VPD), it is essential to understand how these stimuli affect stomatal behavior. It is unknown whether stomatal responses to sub-ambient and above-ambient CO2 levels are governed by the same regulators and whether these responses depend on VPD. We studied stomatal conductance responses in Arabidopsis stomatal signaling mutants under conditions where CO2 levels were either increased from sub-ambient to ambient (400 ppm) or from ambient to above-ambient levels under normal or elevated VPD. We found that guard cell signaling components involved in CO2-induced stomatal closure have different roles in the sub-ambient and above-ambient CO2 levels. The CO2-specific regulators prominently affected sub-ambient CO2 responses, whereas the lack of guard cell slow-type anion channel SLAC1 more strongly affected the speed of above-ambient CO2-induced stomatal closure. Elevated VPD caused lower stomatal conductance in all and faster CO2-responsiveness in some studied genotypes and CO2-transitions. Our results highlight the importance of experimental set-ups in interpreting stomatal CO2- responsiveness, as stomatal movements under different CO2 concentration ranges are controlled by distinct mechanisms. Sometimes elevated CO2 and VPD responses also interact. Hence, multi-factor treatments are needed to understand plant behavior under future climate conditions.

plant biology↗

bioRxiv2018

Complexity of ABA signaling for stomatal development and aperture regulation

Stomata, small pores on the surfaces of leaves formed by a pair of guard cells, adapt rapidly to changes in the environment by adjusting the aperture width. As a long term response, the number of stomata is regulated during stomatal development. The hormone abscisic acid (ABA) regulates both processes. In ABA mediated guard cell signaling the protein kinase OPEN STOMATA1 (OST1) has a central role, as stomatal closure in the ost1 mutant is impaired in response to ABA and to different environmental stimuli. We aimed to dissect the contribution of different ABA-related regulatory mechanisms in determining stomatal conductance, a combination of stomatal density and aperture width, and crossed the ost1 mutant with mutants that either decreased (aba3) or increased (cyp707a1/a3) the concentration of ABA in plants. The double mutant ost1 aba3 had higher stomatal conductance than either parent due to a combination of increased stomatal aperture width and higher stomatal density. In the triple mutant ost1 cyp707a1/a3 stomatal conductance was significantly lower compared to ost1-3 due to lower stomatal density. Further characterization of the single, double and triple mutants showed that responses to treatments that lead to stomatal closure were impaired in ost1 as well as ost1 aba3 and ost1 cyp707a1/a3 mutants, supporting a critical role for OST1 in stomatal aperture regulation. Based on our results, we suggest that there are two signaling pathways to regulate water flux from leaves i.e. stomatal conductance: an ABA-dependent pathway that determines stomatal density independent of OST1; and an OST1-dependent pathway that regulates rapid changes in stomatal aperture.

plant biology↗