Golden rice was discovered by A. Ingo Potrykus and Peter Beyer B. Watson and Crick C. Waldeyer D. Holley -- View Answer 2. Protoplasts obtained through enzymatic degradation was discovered by A. Cocking B. Bergmann C. Mariani D. Takuji -- View Answer 3.
Consider the following statements and select your answer. Assesertion A : Potable water is safe. Reason R : It is free from pathogens, harmful chemical substances, free from color and odor.
The DNA within mitochondria would break down. The mitochondria and chloroplasts would divide. There would be no change in cell function. Apr 07 AM. Expert's Answer Solution. Feedback :. Next Previous. Related Questions. Table 6. Amyloplasts are characterized by starch granules that store high density starch. During the formation of amyloplast membranes, various lipids such as free fatty acids, lysophospholipids, lysophosphatidylcholine, and lysophosphatidylethanolamine are also included in the starch granules Gayral et al.
It is interesting that the amyloplasts is not stable in some cases, for example in Arabidopsis leaves, the accumulation and the loss of starch are highly dynamic, following a daily cycle due to photosynthetic activity or its absence Fernandez et al.
Unlike other types of plastid, amyloplasts often coexist with different types of plastid in the same cell. However, in the tissues of species, such as the winter squash, peach palm fruit, and sweet potato tuber Jeffery et al. Starch granules are also found inside different types of plastids such as chloroplasts.
As well as their storage functions, the amyloplast from Arabidopsis roots were reported to contribute to gravitropism signaling Chen et al. Elaioplasts are characterized by ultrastructures filled with hydrophobic contents such as lipids and terpenoids.
They are specialized for biosynthesis and the storage of lipids, but also have diverse functions in specific tissues. In citrus fruits, elaioplasts are exported into secretory pockets and they can have large impacts on aroma and taste Zhu et al. In pollen, exine formation was found to be highly dependent on elaioplasts Quilichini et al. In specific cases, protein bodies can be found in plastid structures, generally in the cytosolic area, and these are called proteinoplasts or proteoplast, aleuroplast, aleuronaplast; Dashek and Miglani, Proteinoplasts are generally found in many different types of cell at several different stages of plastid development Thomson and Whatley, Due to the location and contents of proteinoplasts, they are thought to have a role in protein storage.
Furthermore, the proteinoplasts of tobacco root showed strong oxidase activity which may convey a specific function Vigil and Ruddat, Chromoplasts have colorful characteristics as they accumulate large amounts of carotenoids and their specific colors are determined by specific types of carotenoids. During chromoplast development, the concentrated carotenoids which form globular, round, coiled shaped carotenoid crystals at the mature stage are produced and stored in hydrophobic structures called plastoglobules Schweiggert et al.
The plastoglobules are lipoprotein particles attached to thylakoids through a half-lipid bilayer and function in both lipid biosynthesis, storage and cleavage Austin et al.
These colored plastids with highly developed plastoglobules are used to attract pollinators and seed disseminators in reproductive tissues or for the storage of carotenoids and hydrophobic metabolites Rottet et al. Gerontoplasts are chloroplast-derived plastids adjusted for recycling of plastid which are mainly found during senescence processes or under stress condition Biswal et al.
When the senescence process starts, plastids undergo serial changes in their ultrastructures. It is difficult to define the characteristics of gerontoplasts at the beginning of senescence, but there are a few specific characteristics that have been identified Biswal et al.
First, gerontoplasts do not contain starch granules, probably because they are unable to continue photosynthesis which replenish the starch daily. Second, their thylakoid structures and chlorophyll have also been degraded. Third, the size of their plastoglobules is enlarged and their numbers increased, probably due to the accumulation of lipophilic substances from degraded lipid structures and hydrophobic contents.
Desiccoplasts are plastids that can be interconverted between chloroplasts and proplastids in desiccation tolerant plants Solymosi et al. Phenyloplasts are phenol enriched colorful plastids identified as a new plastid type when compared to chromoplasts because of their different storage contents and the homeostatic roles of phenols Brillouet et al.
Xyloplasts are specialized plastids in secondary vascular tissues that are dedicated to the synthesis of precursors for monolignol production, derived from either proplastids, or more likely, amyloplasts Pinard and Mizrachi, Transitions of proplastids to chloroplasts mainly occur in the shoot apical meristem and during embryogenesis Table 1.
According to Arabidopsis research, the process of differentiation starts with the shoot apical meristem of the young leaf and continues into leaf development. The differentiation process occurs in the upper layer and central subtending cell layers, and is not affected by the intensity of light, but a light period of 5—10 h is required Yadav et al.
By observing embryonic development in Arabidopsis, chloroplast-containing cells were identified at the globular stage of embryogenesis, indicating the development of chloroplasts from undifferentiated proplastids Tejos et al. In in vitro experiments, dark grown calluses only had proplastids while those grown in the light had short thylakoids and chloroplasts containing an immature membrane structure Ladygin et al.
Table 1. Plastid transitions according to plant phenotypes in the view of greening status. When etioplasts are exposed to light, protochlorophyllide, the chlorophyll precursor of prolamellar bodies, is immediately converted to chlorophyllide by light-dependent NADPH:Pchlide oxidoreductase.
Following this, chlorophyllide is converted to chlorophyll through enzymatic processes Fujii et al. De-etiolation studies using tobacco leaves reported that the physical structures of the etioplast prolamellar bodies changed almost immediately when exposed to light, and regularity and size reductions occurred Armarego-Marriott et al.
Non-photosynthetic leucoplasts can be converted to photosynthetic chloroplasts. In the cortical parenchyma tissues of potato tubers, directly beneath the periderm, amyloplasts starch enriched leucoplast are converted to chloroplasts by the accumulation of chlorophylls under light sources Tanios et al. In addition, the needle leaf of Norway spruce Picea abies also showed the plastid transitions according to growth and seasonal changes.
In Norway spruce, amyloplasts for nutrient accumulation and chloroplasts for photosynthesis are generated at the seedling stage. Seasonally, amyloplasts appear mainly due to the accumulation of large amounts of starch in the autumn and winter and are converted back to typical chloroplasts in the spring and summer Senser et al. For Italian arum Arum italicum fruits, greening proceeds after the fruits are formed.
As the green color emerges, the amyloplasts are converted to chloroplasts with thylakoid membrane development and the plastoglobules increase in number and size Bonora et al. Cucumber thylakoids are decomposed as the fruit matures, and then the thylakoid is reconstituted due to regreening. The plastids of mature fruit and the regreened chloroplasts show morphological similarities, which means re-differentiation of the plastids.
Reconstitution of the thylakoids begins with membrane-bound bodies, and surface expansion and fragmentation occur. Afterward, tubules and double-membrane sheets are formed. The plastoglobuli remain in the plastid even during reconstruction.
This transition implies that several types of membrane structures are associated with the plastid envelope during chloroplast re-differentiation Prebeg et al. Light is regarded as a key factor that greatly influences regreening. As a result of irradiating the citrus fruit Valencia orange with a blue LED light, the tissue was gradually greened, and after 4 weeks, the chlorophyll content was approximately twice as high as that of the unirradiated tissue Ma et al.
When seeds are buried underground without light, but with sufficient environmental conditions for germination, the proplastids can develop into etioplasts while the plants etiolate. This transition is widely adopted by most plants and is an efficient strategy for seedlings in light-seeking circumstances. According to studies on Arabidopsis and soybeans, etioplast formation is influenced by etiolation time, and the efficient tubular-lamellar arrangement affects subsequent vegetative growth Kakuszi et al.
The key element to maintaining etioplasts is the completely dark environment. The loss of negative regulators of photomorphogenesis DET1, COP1, and a combination of PIFs inhibited etioplast differentiation in dark conditions, thereby suggesting that etioplasts develop in dark conditions via the negative regulation of photomorphogenesis Wei et al.
The development of amyloplasts can be observed in most tissues with high-starch contents. Starch is often stored in the root tissues of plants, such as with Arabidopsis Kiss et al.
Furthermore, the tubers and stolons of potatoes are representative organs that accumulate amyloplasts Naeem et al. For apples, in vitro experiments showed that the formation of amyloplasts occurs in the callus and endosperm Sagisaka, For rice and wheat, the accumulation of amyloplasts mainly found in the endosperm Wurtzel et al.
In amyloplasts, starch is produced in the matrix space stroma and forms starch grains, which exhibit different morphologies depending on the plant species and have been intensively studied in various staple crops. The elaioplasts have been largely reported in flowers and they can be found in their ovaries, ovary epidermis, and innermost tapetum cell of the anther wall Chen et al.
Elaioplasts were also reported in secretory ducts of the stem and leaf epidermis from Centaurea cyanus and Haemanthus albiflos Kwiatkowska et al. The formation of elaioplasts has been reported to occur by a diverse range of mechanisms that vary by species. Proteinoplasts have been studies in detail from the roots of tobacco Vigil and Ruddat, They are mainly distributed in the vacuolate and root cap cells of the root and accumulate in the slender tubules of the plastids.
As cells divide, protein accumulation occurs, tubules expand, and protein bodies of dense spheroidal structures appear. In addition, a proteinoplast with a granular matrix containing a large amount protein was reported in the leaves of mung bean Dashek and Miglani, The transition from proplastid to chromoplast is often found during fruit maturation.
Representative examples of the transition from proplastid to chromoplast can be found in watermelon Citrullus lanatus , papaya Carica papaya , and carrot calluses. In papaya during early white maturation, undifferentiated proplastids and globular plastids were dominant, but intermediate plastids such as the chloroplasts and amyloplasts were not found until chromoplasts developed. They were thus thought to have differentiated from the proplastids Schweiggert et al.
In watermelon, similar chromoplast development with an analysis of the pattern of each color step has been reported. When looking at the plastid differentiation patterns of watermelon, the accumulation of carotenoids and chromoplasts appeared according to the maturity of the fruit. In addition, many plastoglobuli were accumulated in the chromoplasts of yellow and orange watermelons when compared to white watermelons.
The red watermelon chromoplasts formed an elongated or irregular structure, and the number of plastoglobuli further increased Fang et al.
In the carrot callus system, proplastids could be converted into chromoplasts during callus differentiation. In the case of pale-yellow carrot calluses, the carotenoid content was low while most of the plastids were proplastids. Conversely, for dark-orange carrot calluses, there were a large amount of chromoplasts, with high carotenoid contents, while the number of proplastids was significantly reduced Oleszkiewicz et al.
Meanwhile, the Arabidopsis callus contains proplastids, but the induced or stable overexpression of a phytoene synthase gene PSY showed the increased carotenoid contents with the chromoplast development Maass et al. This transition occurs during the maturation of fruits, flowers, and roots Sun et al. Relatively well-studied cases for this transition are carrots Daucus carota and orange cauliflower mutants Brassica oleracea L. In the case of carrot roots, the types of plastids present differed markedly depending on the color.
The root of orange carrots was rich in chromoplasts with crystal-shaped structure due to carotene, whereas white carrots had fewer chromoplasts and no crystal-shaped structure. Instead, the white carrot roots showed amyloplasts filled with starch grains, and the total number of the chromoplasts and amyloplasts did not show any significant differences Kim et al.
Chromoplast transitions could also be found in the endosperms of rice and corn, which are mostly formed by amyloplasts. Chromoplasts synthesize and store carotenoids and are mainly found in petals and fruits, which are organs related to reproduction, but they can also occur in the leaves and roots. The transition from chloroplast to chromoplast starts from the breakdown of thylakoids and chlorophyll. This is followed by the increases of plastoglobuli size and the biosynthesis and accumulation of the carotenoids Wrischer and Devide, Representative cases showing the irreversible process from chloroplast to chromoplast were found in tomato Solanum lycopersicum Egea et al.
Interestingly, with single gene overexpression, such as the AtPSY overexpression line in Arabidopsis and the Pantoea ananatis phytoene synthase crtB overexpression by viral vector in tobacco were able to develop the chromoplast from leaf tissues Maass et al. According to a recent report about the modifications of membrane structure in tomato chloroplasts, it was observed that the inner envelope membrane and thylakoid membranes disappeared during the transition to chromoplasts, and new factors plastoglobules and crystal remnants, etc.
One of the well-known examples for de-greening to leucoplast is Arabidopsis flower development. Young petals that have just bloomed contain green chloroplasts throughout their structures, but as the petals expand and develop, they lose chlorophyll and these regenerate into white bodies.
During this process, plastids break down chlorophyll, and carotenoids are not synthesized Pyke and Page, ; Irish, Gerontoplasts are known to occur in both photosynthetic and non-photosynthetic organs as they appear with aging. In general, as chloroplasts age, although their outer shell remains intact, plastoglobuli are formed along with lipophilic substances, and extensive structural changes of the thylakoid membrane occur. In Arabidopsis, observations of gerontoplasts found that they had a degenerated outer shell and thylakoid membranes of chloroplast, enlarged plastoglobuli and grana, and these are gradually increased as they aged Evans et al.
Another study of the structural characteristics of gerontoplasts during Jatropha curcas seed development, found that the inner membrane system thylakoid membrane and plastid outer envelope membrane decomposed, and then there was gradual decomposition of the substrate and plastoglobuli Shah et al.
Recently, research on the regulatory pathways for plastids has largely expanded with many astonishing findings. So, due to considering the diversity and complexity of the plastid, most of the reviews for plastid related signals focused on specific aspects, such as plastid differentiation Liebers et al. In this review, we focused on the post-transcriptional regulation and newly found regulators for plastid transitions Figure 2.
Figure 2. Schematic diagram of the plastid transition regulations. The regulatory mechanisms of greening and non-greening plastid interconversions are briefly summarized with core transcriptional and post-translational regulators.
The light signals from different wavelengths are indicated with thick arrows with representative colors. The photoreceptors are shown with circles, while regulatory genes are shown within rectangular boxes.
E3 ligase complexes, chloroplast biogenesis related enzymes, and chromoplast biogenesis related enzymes were categorized with white brown, green, and orange-colored boxes, respectively.
DNA helix symbols represent the transcriptional regulation of genes. Light is the primary signal for chloroplast development.
To take advantage of rapid response, the plants use post-transcriptional regulation by transferring the signal to E3 ligase mediated protein degradation pathways. HY5 , HYH , and HFR1 were reported as positive transcriptional regulators used to assemble light signals for hypocotyl elongation and early light responses.
This also triggered the transcriptional regulation of core positive regulators to give synergetic effects.
Several regulators play essential roles in chromoplast transition, but they are not as well-established as in chloroplasts. Another positive regulator, OR , was responsible for the generation of chromoplasts in floral organs of cauliflower Brassica oleracea var. OR was also reported to have holdase chaperone activity for PSY , as it enhanced the PSY protein stability and increased its enzymatic activity Welsch et al.
And diverse mutant analysis with different species indicates the essential roles of OR gene in chromoplast development Kim et al. Furthermore, the exogenous induction of rate-limiting carotenoid biosynthesizing enzymes able to trigger the interconversion of plastids to chromoplasts Ha et al. Diverse environmental stresses and developmental signals including ripening could also trigger chromoplast development through the induction of carotenoid biosynthesis Bouvier et al.
From the overview of diverse representative, sophisticate adjustment of plastid interconversion revealed as essential element for multiple agronomic traits.
Not only the photosynthesis related yield potential, many plant-derived biproducts including starch, lipid, protein and secondary metabolites have been determined by development and interconversion of plastid. Although, under the demands from the plants are continuously increased with limited environmental condition, this review suggest the study of plastid can be the breakthrough solution and supports the plastid research by representative scientific reports of plastid interconversion types and core regulators for molecular modification candidates.
Finally, the candidates from the well summarized molecular pathway for plastid interconversion can be applied as target gene for improving multiple agronomic traits which are related to plastid interconversion. S-HH designed the concept and the organization of the manuscript. HC and TY wrote and edited the manuscript. All authors have read and approved the final manuscript. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Are you guys here? So look at this. Based off arenas. Um, we are aware of that. The aren't, um, pro carry attics, pro carry outs. And also they are found and other things. And not just only an fungi, um, and they aren't single membrane Niedere. So, um yeah. So based off those two, we got C and E. Which one do you believe it's, um um, the plot that plots did, um, much better if you said my path. If you said e you are correct. It makes sense that the information that I purposely left out is that it may contain various pigments.
Or probably Sacha writes, if you've got to write the job, if not, it's okay. Um, yeah, it's okay. That's why we're here to help you guys out. And I hope this was very helpful.
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