Betula papyrifera trees were exposed to elevated concentrations of CO(2) (1.4 x ambient), O(3) (1.2 x ambient) or CO(2) + O(3) at the Aspen Free-air CO(2) Enrichment Experiment. The treatment effects on leaf surface characteristics were studied after nine years of tree exposure. CO(2) and O(3) increased epidermal cell size and reduced epidermal cell density but leaf size was not altered. Stomat...

BACKGROUND AND AIMS Genome size is known to affect various plant traits such as stomatal size, seed mass, and flower or shoot phenology. However, these associations are not well understood for species with very large genomes, which are laregly represented by geophytic plants. No detailed associations are known between DNA base composition and genome size or species ecology. METHODS Genome siz...

Variation in ploidy levels in Phragmites australis is a welldocumented phenomenon although North American populations are less studied than European ones. It has been suggested, based on morphological measurements, that native and introduced P. australis subspecies in North America represent different ploidy levels. The objectives of this study were to assess whether guard cell size and stomata...

BACKGROUND AND AIMS Micro-morphological characteristics can influence fungal infectivity. We sought links between micro-morphology and resistance to powdery mildew in mulberry with the intention of assisting selection of disease-resistant lines. METHODOLOGY Over 3 years and under field conditions, we evaluated 30 lines of mulberry with contrasting susceptibilities to powdery mildew (15 resist...

ABSTRACT Physiological and structural alterations in broad beans (Vicia faba cv. Giza Blanka) in response to 10 M CuSO4, 10 M CdSO4 and a mixture of both solutions were recorded in 15and 25day-old plants. These treatments caused significant reductions in shoot height, leaflet area, fresh and dry weights, stomatal frequency, cell area in abaxial epidermis of leaflets, length and width of stomata...

Stomata are simultaneously tasked with permitting the uptake of carbon dioxide for photosynthesis while limiting water loss from the plant. This process is mainly regulated by guard cell control of the stomatal aperture, but recent advancements have highlighted the importance of several genes that control stomatal development. Using targeted genetic manipulations of the stomatal lineage and a c...

Acclimation to CO2 enrichment was studied in maize plants grown to maturity in either 350 or 700 microl l-1 CO2. Plants grown with CO2 enrichment were significantly taller than those grown at 350 microl l-1 CO2 but they had the same number of leaves. High CO2 concentration led to a marked decrease in whole leaf chlorophyll and protein. The ratio of stomata on the adaxial and abaxial leaf surfac...

Motivated by studies suggesting that the stomata of ferns and lycophytes do not conform to the standard active abscisic acid (ABA) -mediated stomatal control model, we examined stomatal behavior in a conifer species (Metasequoia glyptostroboides) that is phylogenetically midway between the fern and angiosperm clades. Similar to ferns, daytime stomatal closure in response to moderate water stres...

Root colonization of plants with certain rhizobacteria, such as Pseudomonas chlororaphis O6, induces tolerance to biotic and abiotic stresses. Tolerance to drought was correlated with reduced water loss in P. chlororaphis O6-colonized plants and with stomatal closure, indicated by size of stomatal aperture and percentage of closed stomata. Stomatal closure and drought resistance were mediated b...

Cycloheximide was shown to block abscisic acid (ABA) biosynthesis in nonstressed as well as in stressed Phaseolus vulgaris leaves. Leaf wilting caused by cycloheximide resulted from increased stomatal opening as judged by a decreased stomatal diffusion resistance. The inhibition of ABA biosynthesis by cycloheximide was at least partially responsible for the increase in stomatal opening as sugge...