Number Of Chloroplasts In Cells Research Articles

Cytological methods of analysis of haploid plants-regenerants of cabbage (<i>Brassica oleracea</i> L.) obtained <i>in vitro</i>

Relevance Currently, in genetic studies and selection of cabbage cultures, biotechnological methods for creating clean lines — doubled haploids in the culture of anthers and in the culture of isolated microspores are widely used. A common feature of these technologies is that the plants obtained in vitro have different levels of ploidy and along with doubled haploids there are haploid, tetraploid and mixoploid forms. Therefore, the use of new cytological methods of analysis of haploid plants remains an urgent problem. Material and method The aim of this work is to establish the genetic nature of regenerated plants of Brassica oleracea L., obtained from reproductive organs in vitro. Isolated anthers and ovaries of white cabbage were cultivated on solid nutrient media containing mineral salts according to the recipe Murashige and Skoog (MS). The obtained regenerated plants were used to calculate the number of chromosomes in the root meristem, as well as the number of chloroplasts in the cells of the closing stomata of leaves using the new universal method of preparing preparations of plant chromosomes – “SteamDrop”. Results As a result of the research, the dependence of the level of ploidy on the cultivation conditions was studied. It has been shown that plants-regenerants of white cabbage, obtained in vitro from reproductive organs, had a different set of chromosomes (n, 3n, 5n). It was established that the number of chloroplasts in the stomatal cells of regenerated plants was from 9 to 45, while the original donor plants had 18–20.

Epiplastome Variation of the Number of Chloroplasts in Stomata Guard Cells of Sugar Beet (Beta vulgaris L.)

In stomata guard cells of sugar beet, variation in the number of chloroplasts was studied in successive generations: (1) hybrid generation; (2) generation yielded by uniparental apozygotic seed reproduction; (3) generation obtained after seed treatment with a colchicine solution; (4) generation obtained after seed treatment with 5-azacytidine. As compared to hybrid generation, uniparental seed reproduction increases the average number of chloroplasts in stomata guard cells (from 13.5 to 15.0) and decreases distribution variance of this trait by a factor of 3 to 4. Colchicine increases both average number of chloroplasts in stomata guard cells (from 13.5 to 18.2) and distribution variance (about twice). 5-Azacytindine reduces the number of chloroplasts in cells (from 15.0 to 12.9) but enhances distribution variance (about 1.5 times). Variation in the number of chromosomes in stomata cells is related to myxoploidy in meristem tissue, on the one hand, and to the rate of cell division, on the other. Uniparental seed reproduction is suggested to enhance the number of organelles per cell due to high myxoploidy in cell populations, which is typical of inbred plants. Colchicine blocks spindle division and sharply increases the level of myxoploidy in cell populations and the number of organelles per cell. 5-Azacytidine hypomethylates chromosome DNA, increases the rate of cell divisions, and reduces the number of organelles per cell. The described changes in the number of chloroplasts are inherited in cell lineage ("cell hereditary memory") and successive sporophyte generations.

Modelling of variability in chloroplast number of stomatal guard cells of sugar beet

Variability in chloroplast number of stomatal guard cells of inbred line of sugar beet was studied in correlation with the level of cell populations mixoploidy. Control plants (seeds were soaked in distilled water before sowing) were compared with plants under the study (seeds were soaked in a weak colchicin solution for 24 hours before sowing). The variability of chloroplast number in stomata guard cells for both control and experimental plants can be described by either binomials with integer positive indexes or integer negative indexes (negative binomials), or Neyman “contagious” distribution. It was demonstrated that both cell population mixoploidy level and variability of chloroplast number in cells rise when plants get older. A comparison in plants of the first and second years of vegetation was also studied.

Relation between chloroplast replication and cell division in olisthodiscus luteus

The number of chloroplasts found in cells of the unicellular alga Olisthodiscus luteus Carter (Chrysophycophyta, Chrysophyceae) at various points of the growth curve were shown to be significantly different. Chloroplast replication and cell division were tightly coupled during the logarithmic phase of growth, while chloroplast replication fell behind cell division when the culture entered the linear growth phase. The chlorophyll content per cell remained constant during the increase of the culture density — thus the amount of chlorophyll per plastid rose with the decline of the chloroplast number per cell. A rapid increase of the cell's chloroplast number prior to the onset of cell division was found in cultures provided with fresh medium. The lower chloroplast number observed in ageing cultures is thought to be due to a limited separation of the chloroplast ER, while the rapid increase of the organelle number in young inocula is interpreted as completion of the last step in chloroplast replication, namely the fission of the chloroplast ER.