Unravelling the neglected role of ultraviolet radiation on stomata: A meta‐analysis with implications for modelling ecosystem–climate interactions

Abstract

Stomata play a pivotal role in regulating gas exchange between plants and the atmosphere controlling water and carbon cycles. Accordingly, we investigated the impact of ultraviolet‐B radiation, a neglected environmental factor varying with ongoing global change, on stomatal morphology and function by a Comprehensive Meta‐Analysis. The overall UV effect at the leaf level is to decrease stomatal conductance, stomatal aperture and stomatal size, although stomatal density was increased. The significant decline in stomatal conductance is marked (6% in trees and >10% in grasses and herbs) in short‐term experiments, with more modest decreases noted in long‐term UV studies. Short‐term experiments in growth chambers are not representative of long‐term field UV effects on stomatal conductance. Important consequences of altered stomatal function are hypothesized. In the short term, UV‐mediated stomatal closure may reduce carbon uptake but also water loss through transpiration, thereby alleviating deleterious effects of drought. However, in the long term, complex changes in stomatal aperture, size, and density may reduce the carbon sequestration capacity of plants and increase vegetation and land surface temperatures, potentially exacerbating negative effects of drought and/or heatwaves. Therefore, the expected future strength of carbon sink capacity in high‐UV regions is likely overestimated.

NO and H2S Contribute to Crop Resilience against Atmospheric Stressors

“…Thus, it is well established that stomata movement as it has happened with photosynthesis activity can be affected by numerous atmospheric pollutants [ 63 , 64 , 65 , 66 , 67 , 68 ].…”

“…On the other hand, ethylene induces H2S production in guard cells and this H2S can then inhibit the synthesis of ethylene by the inhibition of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) activity by persulfidation (Cys-SSH) at Cys60 [62]. Thus, it is well established that stomata movement as it has happened with photosynthesis activity can be affected by numerous atmospheric pollutants [63][64][65][66][67][68].…”

“…At the same time, it is important to note that atmospheric • NO/NOx and H2S may be adsorbed at the leaf's surface through the stomata [65,[78][79][80], and depending on their concentration, these gases can have either negative or beneficial effects on higher plants. For example, it has been pointed out that • NO Thus, it is well established that stomata movement as it has happened with photosynthesis activity can be affected by numerous atmospheric pollutants [63][64][65][66][67][68].…”