Assessment of the Value of Stomatal Size and Density as Hallmarks of Nonaploid Kiwifruit Plants

In vitro-derived plants with elevated ploidy levels can display distinguishing features from the plants they are derived from, especially owing to their indirect regeneration. Genome size affects cell size and, thus, affects plant morphological characteristics. Therefore, stomata traits may be used as a diagnostic feature allowing identification of ploidy. Actinidia chinensis var. deliciosa A. Chev. (A. Chev.), known as kiwifruit, is successfully cultured in vitro and redifferentiated into plants via endosperm-derived calli. To identify differences between hexaploids obtained from seeds and confirmed nonaploids obtained from endosperm-derived calli, we analyzed the stomata. Our results confirmed that ploidy coincides with mean stomatal length, width, and density. Despite this correlation, this method cannot be used to distinguish individual hexaploid kiwifruit plants from nonaploid ones because samples with different ploidy yielded overlapping measurements.

Responses of Leaf Hydraulic Traits of Schoenoplectus Tabernaemontani To Increasing Temperature and CO2 Concentrations

Background Against the background of a changing climate, the responses of functional traits of plateau wetland plants to increasing temperatures and CO2 concentrations need to be understood. Hydraulic traits are the key for plants to maintain their ecological functions and affect their growth and survival. However, few studies have comprehensively considered the response strategies of wetland plants' hydraulic traits to environmental changes in the context of water and matter transport, loss, and retention. According to the latest IPCC prediction results, we performed experiments under increased temperature (2℃) and CO2 levels (850 µmol/mol) in an artificial Sealed-top Chamber (STC) to investigate the responses of the hydraulic characteristics of Schoenoplectus tabernaemontani, the dominant species in plateau wetlands in China. Results Compared with the CK group, net photosynthetic rate, transpiration rate, stomatal length, cuticle thickness, vascular bundle length, vascular bundle width, and vascular bundle area of S. tabernaemontani in the ET group were significantly reduced, whereas stomatal density and vein density increased significantly. Compared with the CK group, the hydraulic traits of S. tabernaemontani in the EC group were reduced considerably in stomatal length and cuticle thickness but increased dramatically in stomatal density, and there were no significant differences between other parameter values and the control group. Net photosynthetic rate was significantly positively correlated with stomatal length, cuticle thickness, and vascular bundle length, and stomatal conductance was significantly positively correlated with cuticle thickness. The transpiration rate was significantly positively correlated with cuticle thickness, epidermal cell area, vascular bundle length, vascular bundle width, and vascular bundle area. Regarding the hydraulic traits, there was a significant negative correlation between stomatal density and stomatal length, or cuticle thickness, and a significant positive correlation between the latter two. The epidermal cell area was significantly positively correlated with epidermal thickness, vascular bundle length, vascular bundle width, and vascular bundle area Conclusions Increased temperature and CO2 levels are not conducive to the photosynthetic activity of S. tabernaemontani. Photosynthetic rate, stomatal density and size, vein density, epidermal structure size, and vascular bundle size play an essential role in the adaptation of this species to changes in temperature and CO2 concentration. In the process of adaptation, hydraulic traits are not isolated from each other, and there is a functional association among traits. This study provide a scientific basis for the management and protection of plateau wetlands.

Coupling Relationship of Leaf Economic and Hydraulic Traits of Alhagisparsifolia Shap. in a Hyper-Arid Desert Ecosystem

In this study, Alhagisparsifolia Shap. was used to test the hypothesis that leaf economic and hydraulic traits are coupled in plants in a hyper-arid region. Five economic traits and six hydraulic traits were examined to explore the relationship. Results showed that the stomatal density (SD) on both surfaces was coupled with maximum stomatal conductance to water vapor (gwmax) and leaf tissue density (TD). SD on adaxial surface (SDaba) was significantly positively related to vein density (VD) but negatively related to leaf thickness (LT) and stomatal length on adaxial surface (SLada). Nitrogen concentration based on mass (Nmass) was significantly negatively correlated with leaf mass per area (LMA), LT, and VD, whereas nitrogen concentration based on area (Narea) was significantly positively related to LMA and TD. Mean annual precipitation (MAP) contributed the most to the changes in LT and stomatal length (SL). Soil salt contributed the most to TD, SD, and gwmax. Soli nutrients influenced the most of LMA and VD. Mean annual temperature contributed the most to Nmass and Narea. In conclusion, the economics of leaves coupled with their hydraulic traits provides an economical and efficient strategy to adapt to the harsh environment in hyper-arid regions.

Developmental integration cannot explain major features of stomatal anatomical evolution in seed plants

Developmental integration can cause traits to covary over macroevolutionary time and in some cases prevent populations from reaching their adaptive optima. Developmental integration between stomatal size and density may contribute to two major features of stomatal anatomical evolution: inverse size-density scaling and bimodal stomatal ratio. If these patterns result from developmental integration, we predicted that in amphistomatous leaves 1) stomatal size and density should covary similarly on both abaxial and adaxial surfaces and 2) stomatal traits (size and density) on each surface should covary isometrically. We synthesized data on stomatal density and length from amphistomatous leaves of 711 terrestrial seed plant taxa mostly from the literature. We estimated the covariance in divergence between stomatal traits from 327 phylogenetically independent contrasts using a robust Bayesian model. Adaxial stomatal density, but not length, is evolutionarily labile and not strongly integrated with stomatal length or abaxial stomatal density. Hence, developmental integration alone cannot explain inverse size-density scaling nor bimodal stomatal ratio. Quasi-independent evolution of stomatal anatomical traits facilitates largely unfettered access to fitness optima. If stomatal anatomical traits are near their current fitness optimum, this implies that limits on trait (co)variance result from selective rather than developmental constraints. However, we cannot rule out that developmental integration is important in some lineages. Future research should identify the mechanistic basis of(dis)integration in stomatal development.

Diversity of Leaf Stomatal Traits among Coffea canephora Pierre ex A. Froehner Genotypes

Leaf morpho-anatomical characteristics directly reflect photosynthetic performance and the ability to adapt to different environmental conditions. The study of biometric traits is essential for the selection of promising plant materials for breeding purposes. To identify new varieties of coffee plants with desirable traits for genetic improvement programs, this study investigated the variability of leaf morpho-anatomical traits in 43 genotypes of Coffea canephora (as the species under study is hypostomatous). Seven leaf characteristics were used: epidermal cell density (ECD), stomatal length (SL), stomatal width (SW), stomatal density (SD), stomatal size (SS), stomatal index (SI), and stomatal length/width. Morphological traits (plant height, internodal distance, and leaf area) and grain production were also assessed. The data analyzed multivariate analysis of variance grouped by the unweighted pair group the arithmetic mean hierarchical method, and data were also subjected to a Pearson linear correlation and principal component analyses (PCAs). The results showed wide morphological variability reflecting six morphological groups, which is relevant for the genetic divergence analysis and for breeding purposes, as the results have the potential to identify superior genotypes. Within the groups, genotypes were mainly separated by the number of epidermal cells and the number and size of the stomata, reflecting a high genetic heterogeneity within genotypes. Positive and negative correlations were found, with levels of significance ranging from weak to strong among the analyzed traits. The highest correlation levels were found for SL × SS, SW × SS, and SI × SD. In addition, the PCA indicated that plant height, distance between nodes, and leaf area were positively correlated and associated. The greater the number and width of stomata, the higher the rate of gas exchange. Both characteristics are favorable for the development and production of coffee plants, explaining the positive correlation observed in this study. These results emphasize the usefulness of trait evaluations for the identification and breeding of genotypes to compose new C. canephora cultivars suitable for changing environments.

Revisiting the physical mutagenesis for sugarcane improvement: a stomatal prospective

This study was conducted to investigate the influence of gamma rays on stomatal parameters and the interaction of these traits with agronomy of the sugarcane crop. Three genotypes of sugarcane (NIA-0819, NIA-98, and BL4) were exposed to four doses of gamma radiation (10, 20, 30, and 40 Gy) and then subjected to field trials. Stomatal length, width, and density were observed using scanning electron microscopy. Moreover, agronomic and sugar-related characteristics of the crop were determined at maturity. The stomatal parameters augmented at two lower doses of gamma radiation (10 and 20 Gy) and declined under higher doses (30 and 40 Gy). The maximum stomatal length was observed in NIA-0819 at 10 Gy (63.71 µm), whereas NIA-98 and BL4 demonstrated highest stomatal length under 20 Gy (54.11 and 57.40 µm, respectively), indicating a role of genetic factors in varietal response. Similar trend was noticed for stomatal width and density as well. The lowermost treatment (10 Gy) of NIA-0819 produced maximum stomatal density (115.31 stomata mm-2 on the abaxial surface). Adaxial stomatal density was significantly lower than the abaxial one. Sugar quality attributes revealed a different tendency. Sucrose contents of BL4 increased gradually from 12.33% at control to 14.54% at 40 Gy. Yield and yield-contributing traits of genotypes indicated a strong positive correlation with the stomatal parameters. The present study suggested that gamma radiations cause variations in stomatal characteristics of sugarcane. These changes further influence the photosynthetic activity and instigate a direct impact on the agronomic performance of the crop.

Difference between emergent aquatic and terrestrial monocotyledonous herbs in relation to the coordination of leaf stomata with vein traits

Emergent aquatic plants mostly occur in shallow waters and root in bottom substrates, but their leaves emerge from the water surface and are thus exposed to air, similar to the leaves of terrestrial plants. Previous studies have found coordination between leaf water supply and demand in terrestrial plants; however, whether such a coordination exists in emergent aquatic plants remains unknown. In this study, we analysed leaf veins and stomatal characteristics of 14 emergent aquatic and 13 terrestrial monocotyledonous herb species (EMH and TMH), with 5 EMH and 8 TMH belonging to Poaceae. We found that EMH had significantly higher mean leaf area, leaf thickness, stomatal density, stomatal number per vein length and major vein diameter, but lower mean major vein length per area (VLA) and total VLA than TMH. There was no significant difference in stomatal length, minor VLA and minor vein diameter between the two groups. Stomatal density and total VLA were positively correlated among the EMH, TMH, as well as the 8 Poaceae TMH species, but this correlation became non-significant when data from both the groups were pooled. Our results showed that the differences in water supply between emergent aquatic and terrestrial plants modify the coordination of their leaf veins and stomatal traits.

Effect of colchicine and oryzalin treatment on polyploid induction and morphogenesis of Anoectochilus setaceus Blume cultured in vitro

Jewel orchid (Anoectochilus setaceus Blume) is one of the important medicinal plants used for many common diseases treatment such as hypertension, diabetes, and heart, liver and lung diseases, as well as improving the health in general. Polyploid induction using colchicine and oryzalin has been widely performed in various types of crops and could be considered a valuable tool for plant breeding. In the present study, in vitro young shoots of A. setaceus Blume (1 cm in height) were treated with different concentrations of colchicine (0, 1, 2, 4, 6, 8, and 10 µM) and oryzalin (0, 10, 20, 40, 60, 80, and 100 µM) at different durations (0, 12, 24, 36, and 48 h). The results showed that shoots with length of treatment from 24 to 48 h and the concentrations from 2 to 10 µM of colchicine and from 40 to 100 µM of oryzalin appeared morphological differences (10.00% - 16.00%) but the tendency to return to normal of these shoots after several times of sub-culture was observed. Stomatal length had a close correlation with the level of ploidy. Diploid plantlets (2n = 2x) had the average stomatal length of 33.50 µm when observed under an optical microscope at 100x magnification and corresponding to the peak at 70 FL in flow cytometric DNA histogram. In all identified polyploid plantlets, the stomatal lengths were greater than 40.12 µm. Moreover, flow cytometric analysis indicated that plantlets with stomatal lengths ranged from 40.12 to 50.00 µm were diploid-tetraploid mosaicisms represented by two separate peaks at 70 FL and 90 FL. Finally, samples treated with 4, 6, and 8 µM colchicine with treatment time of 48 h, and 60 µM oryzalin with treatment time of 24 h that had stomatal lengths ranged from 52.03 to 71.25 µm were determined to be tetraploid (2n = 4x) represented by a peak at 120 FL position.

Stomatal Response of Maize (Zea mays L.) to Crude Oil Contamination in Soils

In this study, maize plant was cultured in soil contaminated with different levels of crude oil. The purpose was to investigate the change of soil properties, leaf physiological and chemical parameters, and phenanthrene content in the leaf. Results showed that soil water content significantly increased when the levels of total petroleum hydrocarbons were 3700–17,800 mg/kg in soil, and soil electrical conductivity significantly increased compared with the control. In maize leaf, stomatal length and density, as well as K and Na contents decreased in contaminated treatments compared with the control. Stomatal length has a significant positive correlation with K content in leaf (r = 0.92, p < 0.01), while stomatal density was negatively correlated to the crude oil level in soil (r = −0.91, p < 0.05). Accumulation of phenanthrene in maize leaf was mainly through the foliar uptake pathway. Phenanthrene concentrations of maize leaf in oil-treated soil were less than that of the control, which exhibited a significant positive relationship with stomatal length (r = 0.98, p < 0.01). This study demonstrated that the stomata structure of maize could be influenced by crude oil and thus possibly controlling the accumulation of polycyclic aromatic hydrocarbons in aerial tissues. Based on these results, controlling stomata movement will be beneficial to phytoremediation of contaminated soil.

Keragaman Stomata Okra (Abelmoschus esculentus L. (Moench)

Okra (Abelmoschus esculentus L. (Moench.) is high nutrition compound potential for diabetes and Alzheimer. Yield is one of the characters have to improve in plant breeding program through stomata characterization. The variability for 14 genotypes showed significantly for stomatal length, stomatal width, epidermal cell number, chloroplast number, stomatal number, stomatal index and stomatal density. Stomatal density for P2 was 256.80 mm2 that was nonsignificant with Zahira (265.31 mm2) and Naila (204.08 mm2). Genotypes P2, Zahira and Naila showed low stomatal density that mean efficiency for water management in leaves. The high stomatal index causing high photosynthesis and high yield. Stomatal index were high for genotypes P1 (40.31) and P2 (35.69). Naila has low stomatal index but Zahira as significant as genotype P2. Zahira could be high yield genotype candidate.Keyword : candidate, density, index, genotype