Coordination of leaf hydraulic, anatomical, and economical traits in tomato seedlings acclimation to long-term drought

Background Leaf hydraulic and economics traits are critical for balancing plant water and CO2 exchange, and their relationship has been widely studied. Leaf anatomical traits determine the efficiency of CO2 diffusion within mesophyll structure. However, it remains unclear whether leaf anatomical traits are associated with leaf hydraulic and economics traits acclimation to long-term drought. Results To address this knowledge gap, eight hydraulic traits, including stomatal and venation structures, four economics traits, including leaf dry mass per area (LMA) and the ratio between palisade and spongy mesophyll thickness (PT/ST), and four anatomical traits related to CO2 diffusion were measured in tomato seedlings under the long-term drought conditions. Redundancy analysis indicated that the long-term drought decreased stomatal conductance (gs) mainly due to a synchronized reduction in hydraulic structure such as leaf hydraulic conductance (Kleaf) and major vein width. Simultaneously, stomatal aperture on the adaxial surface and minor vein density (VDminor) also contributed a lot to this reduction. The decreases in mesophyll thickness (Tmes) and chlorophyll surface area exposed to leaf intercellular air spaces (Sc/S) were primarily responsible for the decline of mesophyll conductance (gm) thereby affecting photosynthesis. Drought increased leaf density (LD) thus limited CO2 diffusion. In addition, LMA may not be important in regulating gm in tomato under drought. Principal component analysis revealed that main anatomical traits such as Tmes and Sc/S were positively correlated to Kleaf, VDminor and leaf thickness (LT), while negatively associated with PT/ST. Conclusions These findings indicated that leaf anatomy plays an important role in maintaining the balance between water supply and CO2 diffusion responses to drought. There was a strong coordination between leaf hydraulic, anatomical, and economical traits in tomato seedlings acclimation to long-term drought.

Microscopic Evaluation of Salvia stepposa Des.- Schost above - ground part widespread in Kazakhstan

Microscopic analysis of medicinal plants and raw materials is one of the stages of quality control which makes it possible to determine the authenticity of an object. This article presents the results of microscopic analysis of leaves, corolla, leafstalks and stalk of Salvia stepposa (steppe sage). This species is a relative to Salvia officinalis officinal used in traditional medical systems as an anti-inflammatory agent. The purpose of this study is to determine the features of the anatomical structures of the above-ground part of steppe sage and to reveal diagnostic signs at the microscopic level. Preliminary pharmacognostic investigation of vegetative raw material is done and diagnostic signs are identified. The detail microscopy revealed the presence of 3 types of trichomes on leaves’ epidermis: 1) simple unicellular; 2) simple multicellular; 3) glandular; their localization and shape are determined. Type of mesophyll, structure of trichomes; form and location of epidermal cells, the presence of rare simple trichomes along the edge are discovered. As a result of the research the anatomical features of the raw material were established, which make it possible to identify the above-ground part of Salvia stepposa and can be used for the development of regulatory documentation.

Characterization of Anatomical and Physiological Effects of Variegation Mutation on Grapevine

Variegation is a common trait in plants that characteristically displays white or off-colored plant tissue. In grapevine, leaf variegation is expressed as white and pale green leaf tissue resulting in plants that are stunted in growth and hindered in development. In this study, several experiments were performed to investigate the impact of this mutation has on the anatomy of grape leaves and physiology of the plant. Histological staining of variegated and nonvariegated leaf tissue transections showed alterations to the leaf palisade mesophyll structure that affected leaf tissue width. An assay quantifying leaf pigments was performed to compare chlorophyll and carotenoid concentrations in leaves between variegated and wild-type seedlings, which showed that variegated leaf samples had reduced chlorophyll and carotenoid concentration. Through fluorescence imaging, we determined that photochemical efficiency of photosystem II (PSII) is reduced in variegated seedlings. By growing variegated and wild-type plants under high, medium, and low light intensities that variegated plants exposed to higher light intensity reduces the phenotypic expression of the variegation trait. Also, we found variegated plants to have significant reductions in growth traits such as plant height, leaf number, branch number, and dry weight compared with wild-type phenotype plants. Overall, our experiments revealed the variegation mutation altered normal leaf development causing significant effects to grapevine physiology.

Overproduction of ABA in rootstocks alleviates salinity stress in tomato shoots

To determine whether root-supplied ABA alleviates saline stress, tomato (Solanum lycopersicum L. cv. Sugar Drop) was grafted onto two independent lines overexpressing the SlNCED1 (9-cis-epoxycarotenoid dioxygenase) gene (NCED OE) and wild type rootstocks. After 200 days of salinity irrigation (EC = 3.5 dS m-1), plants with NCED OE rootstocks had 30% higher fruit yield, but root biomass and lateral root development was reduced. Although NCED OE rootstocks upregulated ABA-signalling (AREB, ATHB12), ethylene-related (ACCs, ERFs), aquaporin (PIPs) and stress-related (TAS14, KIN, LEA) genes, downregulation of PYL ABA receptors and signalling components (WRKYs), ethylene synthesis (ACOs) and auxin responsive factors occurred. Elevated SlNCED1 expression enhanced ABA levels in reproductive tissue while ABA catabolites accumulated in leaf and xylem sap suggesting homeostatic mechanisms. NCED OE also reduced xylem cytokinin transport to the shoot and stimulated foliar 2-isopentenyl adenine (iP) accumulation and phloem transport. Moreover, increased xylem gibberellin GA3 levels in growing fruit trusses was associated with enhanced reproductive growth. Improved photosynthesis without changes in stomatal conductance was consistent with hormone-mediated alteration of leaf growth and mesophyll structure, which combined with lower assimilate requirement in the roots and systemic changes in hormone balances could explain enhanced vigour, reproductive growth and yield under saline stress.

Emergent honeycomb topology of the leaf spongy mesophyll

The spongy mesophyll layer in leaves is ubiquitous among vascular plants, yet its structure is relatively unknown and typically described as a disordered assemblage of isodiametric cells. We characterized spongy mesophyll structure among diverse taxa using X-ray microCT imaging and found that leaves with small cell sizes, high cell packing densities, and close vein spacing were congruent with the isodiametric paradigm. When these structural traits exceeded well-defined thresholds, the spongy mesophyll domain was instead tessellated with an emergent topological motif of an irregular honeycomb that minimizes cellular investment and obeys Euler’s Law of space filling. Our data suggest spongy mesophyll is governed by allometric scaling laws, with two distinct topologies optimized for either photosynthetic performance or minimal resource investment.One Sentence SummaryConserved topological motifs in the spongy mesophyll are coordinated with leaf photosynthetic performance.

Micromorphological and anatomical investigation on six species of Onosma L. (Boraginaceae) from Turkey

Micromorphology and anatomy of six Onosma L. species, viz. O. argentata Hub.-Mor., O. neglecta Riedl, O. proballanthera Rech. f., O. rechingeri Riedl, O. sericea Willd. and O. stenoloba Hausskn. ex Riedl from Turky were investigated. Stem anatomy revealed that cuticle layer ranged from 0.6 µm in O. argentata to 1.7 µm in O. proballanthera. Parenchymatous cells of O. neglecta and O. stenoloba possessed more intense starch than the other species studied. In leaf anatomy, the longest palisade parenchyma was found in O. neglecta, while the smallest was noted in O. argentata. Mesophyll structure of O. argentata, O. sericea and O. rechingeri was equifacial (isobilateral), while O. neglecta, O. proballanthera and O. stenoloba presented bifacial (dorsiventral) structure. Rugose nutlet ornamentation was observed in O. argentata, O. neglecta and O. sericea, whereas reticulate type was found in O. proballanthera, O. rechingeri and O. stenoloba. Onosma stenoloba could easily be distinguished from other species by its aesterotrichous indumentum, and in contrary, other species possessed haplotrichous type of indumentum. Micromorphological features of nutlet surface, anatomical features of epidermal surface (trichomes and stomata), and lamina mesophyll structure (dorsiventral and isobilateral) could be useful in solving taxonomic problem of the genus.

SPECTRAL REFLECTANCE OF IPÊ-AMARELO LEAVES UNDER DIFFERENT FORMS OF STORAGE AND COLLECTION TIME

The application of spectroradiometry techniques to the study of tree species allows the acquisition of information related to plant physiology and morphology, which can be used in conjunction with orbital images. However, it is known that when a leaf is extracted the senescence process is started, which is characterized by cell constituents degradation, loss of water and modifications of the foliar mesophyll structure. In this context, this study aimed to evaluate the influence of the collection time and storage form on the spectral response of ipê-amarelo leaves. Thus, 32 leaves were collected in distinct times (1h, 2h, 24h and 48h) and conditioned with(C) and without(S) thermal storage. The data were evaluated from the visual analysis of the spectral curves, derivative analysis and statistical analysis. The experiment was conducted in a Randomized block design and data were submitted to analysis of variance (ANOVA) and Tukey test (p = 0.05). Results indicated that thermal storage might delay the senescence process of the leaves. Both the collection time and the storage form affect the pattern of spectral behavior of the leaves of ipê-amarelo. The collection time has not shown significant differences between 1-2h. The largest differences were found between 2-24h after collection.