title: Dynamics of spatial heterogeneity of stomatal closure in Tradescantia virginiana altered by growth at high relative air humidity.
abstract: The spatial heterogeneity of stomatal closure in response to rapid desiccation of excised well-watered Tradescantia virginiana leaves grown at moderate (55%) or high (90%) relative air humidity (RH) was studied using a chlorophyll fluorescence imaging system under non-photorespiratory conditions. Following rapid desiccation, excised leaves grown at high RH had both a greater heterogeneity and a higher average value of PSII efficiency (Phi(PSII)) compared with leaves grown at moderate RH. Larger decreases in relative water content resulted in smaller decreases in water potential and Phi(PSII) of high RH-grown leaves compared with moderate RH-grown leaves. Moreover, the Phi(PSII) of excised high RH-grown leaves decreased less with decreasing water potential, implying that the stomata of high RH-grown leaves are less sensitive to decreases in leaf water potential compared with moderate RH-grown leaves. After desiccation, some non-closing stomata were distributed around the main vein in high RH-grown leaves. Direct measurements of stomatal aperture showed 77% stomatal closure in the margins after 2 h desiccation compared with 40% closure of stomata in the main-vein areas in high RH-grown leaves. Faster closure of stomata in leaf margins compared with main-vein areas of leaves grown at high RH was related to substantially lower relative water content in these areas of the leaves.
authors.affiliation: Horticultural Production Chains Group, Plant Sciences, Wageningen University, Marijkeweg 22, 6709 PG, Wageningen, The Netherlands. Hossein.Rezaeinejad@wur.nl
authors.forename: Abdolhossein
authors.initials: A
authors.lastname: Rezaei Nejad
authors.forename: Jeremy
authors.initials: J
authors.lastname: Harbinson
authors.forename: Uulke
authors.initials: U
authors.lastname: van Meeteren
mesh_terms: D003890:Desiccation; D006813:Humidity; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology; D034823:Tradescantia / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D014867:Water / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D014867:Water