In sugarcane the early development of the stomate is in general agreement with that characteristic of grasses; the later stages of development involve extensive and intricate thickenings of portions of the walls of the guard cells.
Simultaneous with the extensive thickening of the walls of the central part of the guard cell, a separation of the chromatic material of the guard cell nucleus occurs with the result that the nuclear knobs in the terminal sacks of the guard cells are connected only by a very fine thread of nuclear material which extends through the narrow central part.
Under extreme conditions the knob-like terminals of the dumb-bell-shaped nuclei become so greatly separated that separate spherical nuclei are formed, one in each terminal part of the guard cell. While in some instances these nuclei are smaller than those of adjoining single-nucleated cells, in other instances they are of normal size.
Comparison of in vitro seeds and shoot tips colchicine treatment methods on of Thymus daenensis Celak via the study of morphological features of stomata and cellular DNA content
by Aslani F., Bernard F., Mirzajani F., Hadian J. (2015)
in jppf. 2015; 3 (10) :1-8
Colchicine treatment for the inductive polyploidy on different parts of the plant can affect the results. The aim of present study was to compare the influence of colchicine treatment on seeds and shoot tips of Thymus daenensis plants.
Examination of stomatals morphological features and analyze of cellular DNA content by spectrophotometry is an indirect ways but faster and cheaper to determine ploidy level in plants. To achieve this objective, seeds and shoot tips were treated in different colchicine concentration levels including (0.0%, 0.03%, 0.05%, 0.08%, 0.1% w/v) for 24 and 48 hours and the survival rate of seeds and shoot tips were estimated.
The effect of colchicine was measured by the number of chloroplasts in stomatal guard cells, the density of stomata on the leaf surface and cellular DNA content. Significant decline was seen in both treatment in comparison to the control group but survival rate was significantly higher in shoot tips treatment than seeds.
In seed treatment, frequency of chloroplasts and total DNA content varied significantly in 0.08% colchicine application for 24 hours and significant decrease were found in stomatal density at this concentration. Similar result was seen in shoot tip treatment at the concentration of 0.03% and 0.1% for 48 and 24 hours but only significant change was seen in frequency of chloroplasts.
In conclusion, plant’s section that use for colchicine treatment can affect the results, and despite of reduction of seeds survival rate under colchicine treatment, seeds treatment at the level of 0.08% (w/v) for 24 hours in comparison to the shoot tips treatment is a better way to induce polyploidy.
Variability of Stomatal Index and Chlorophyll Content in four species of Solanaceae Members
by Ajayan K. V., Babu R. L., Bayakka P. B.
in International Research Journal of Biological Sciences, Vol. 4(2), 16-20, February (2015)
The present investigation focuses on stomatal index and chlorophyll contents of species like Datura innoxia L., Capsicum annum L., Lycopersicon esculentum M., Solanum nigrum L. and their comparative account on taxonomic similarity.
There were no relation between stomatal size and growth habitat. Our study revealed that Lycopersicon significantly showing reduced in stomatal size and more in number at the lower epidermis, in addition to size of the stomata and subsidiary cells of these species were closely allied.
All the investigated species has shown anomocytic stomata. The anatomical structure of subsidiary cells shows irregular in shape, size, and numbers. Irrespective of leaf surface they have peculiar types of anomocytic stomata, stomatal type, and stomatal index.
Quantification study of chlorophyll pigment revealed that there is no significant difference among the four species in terms of quantity and taxonomical variations in these species.
Colchicine effect on the DNA content and stomata size of Glycyrrhiza glabra var.glandulifera and Carthamus tinctorius L. cultured in vitro
by Moghbel N., Borujeni M. K., Bernard F. (2015)
in Journal of Genetic Engineering and Biotechnology
In vitro induction of polyploids using colchicine causes an increase in DNA content in plants. This is of high importance especially for plants that have medicinal and commercial values. Seeds of two medicinal plants, licorice Glycyrrhiza glabra L. var.glandulifera and safflower Carthamus tinctorius were treated with different concentrations of colchicine, 0%, 0.03%, 0.05%, 0.08%, 0.1% (W/V) in vitro for 24 and 48 h. Treated seeds then were cultured on solid Murashige and Skoog (MS) media under controlled conditions. After a month, the length of the stomata was measured to study the effect of colchicine on stomata size. Cellular DNA content of the regenerated plants was measured by spectrophotometry. Flow cytometry was used for confirming the results obtained from stomata size measurement and spectrophotometry.
Results suggested that treated plants have a fair amount of larger stomata, significantly in licorice plantlets that were treated with 0.1% colchicine for 24 h and safflower plantlets that were treated with 0.03%, 0.05% and 0.1% colchicine. Safflower DNA content in all treatments enhanced significantly, but in licorice only DNA content of plantlets that were treated with 0.05% colchicine for 24 h and 0.1%, 0.03% colchicine for 48 h found to be increased significantly. The morphological features of treated plantlets such as shoot and leaf thickness were found to be increased. Flow cytometry confirmed the previously mentioned results and suggested tetraploids in all treated safflower plantlets and licorice plantlets obtained from treatment with 0.08% of colchicine and mixoploids in licorice plantlets obtained from treatment with 0.1% of colchicine.
Stomata are minute aperture structures on plants found typically on the outer leaf skin layer, also known as the epidermis. They consist of two specialized cells, called guard cells that surround a tiny pore called a stoma.
The word stomata means mouth in Greek because they allow communication between the internal and external environments of the plant. Their main function is to allow gases such as carbon dioxide, water vapor and oxygen to move rapidly into and out of the leaf.
Stomata are found on all above-ground parts of plants, including the petals of flowers, petioles, soft herbaceous stems and leaves. They are formed during the initial stages of the development of these various plant organs and therefore reflect the environmental conditions under which they grew.
The development of stomata – the epidermal pores on plant leaves that regulate gas exchange – is tightly regulated by various environmental factors. Light, for example, promotes stomatal development; very few stomata are found on the epidermis of dark-grown seedlings.
Here, on p.3165, Ute Hoecker and colleagues report that auxin, acting via Aux/IAA proteins, plays a key role in repressing stomatal development in dark-grown seedlings. The researchers show that aux/iaa mutants, which display auxin insensitivity, exhibit excessive stomata production specifically in dark-grown seedlings.
This stomata-overproducing phenotype is also observed in mutants that are defective in auxin biosynthesis or perception, suggesting that auxin acts to repress stomatal production in the dark. They could further show that the excessive formation of stomata is caused by an increase in cell divisions within the stomatal lineage. Finally, the researchers use a combination of epistasis studies to elucidate a genetic network that integrates light and auxin signals in order to regulate stomatal development.