Here is a compilation of term papers on ‘Synthetic Seeds’ for class 11 and 12. Find paragraphs, long and short term papers on ‘Synthetic Seeds’ especially written for school and college students.
Term Paper on Synthetic Seeds
Term Paper Contents:
- Term Paper on the Definition of Synthetic Seeds
- Term Paper on the Types of Synthetic Seeds
- Term Paper on the Methods of Production of Synthetic Seeds
- Term Paper on the Recent Developments in Synthetic Seed Technology
- Term Paper on the Commercial Production of Synthetic Seeds
- Term Paper on the Potential Uses of Synthetic Seeds
- Term Paper on the Limitations of Synthetic Seed Technology
Term Paper # 1. Definition of Synthetic Seeds:
Synthetic seeds are defined as artificially encapsulated somatic embryos, shoot buds, cell aggregates, or any other tissue that can be used for sowing as a seed and which possess the capability to convert into a plant under in vitro conditions. Somatic embryogenesis, organogenesis and axillary bud proliferation systems are excellent techniques for rapid and mass scale production of synthetic seeds in vitro.
Encapsulation is expected to be the best method to provide protection and to convert the in vitro derived propagules into ‘synthetic seeds’ or ‘synseeds’ or ‘artificial seeds’. The synthetic seed technology combines the advantages of clonal propagation with those of seed propagation and storage.
Term Paper # 2.
Types of Synthetic Seeds:
(i) Hydrated synthetic seeds consist of somatic embryos individually encapsulated in hydrogel such as calcium alginate.
(ii) Desiccated synthetic seeds are produced by coating somatic embryos in polyoxyethylene glycol.
Synthetic seed is a newer concept in seed biotechnological research and is mainly considered for propagation and delivery of tissue cultured plants in a more economical and easy way. Hydrated encapsulation of somatic embryos/propagules from recalcitrant crops has proved useful and provides a method for increasing the short storage life of the seeds. For bio-reaction development and standardizing systems for synchronously developing propagules, followed by automation of the whole process of sorting, harvesting, encapsulation and germination of the coated propagules, can speed up production of synthetic seeds.
T. Murashige (1977) gave the concept of artificial seeds for the first time. Artificial (encapsulated) seeds are the somatic embryos covered with a protecting gel. These seeds are compared to the true seeds. In these seeds, the gel acts as seed coat and artificial endosperm providing nutrient as in true seeds (Fig. 5.1).
Water-soluble gels (hydrogels) must be used as the protective gel. Usually Na/Ca alginate or carrageenan (a product of brown algae) is selected for encapsulation purpose because it is less toxic to embryos and easy to handle. There are several gels used for coating embryoids (Table 5.1). Shoot tips excised from the shoot cultures of banana have been encapsulated in 3% sodium alginate solution. Alginate artificial seeds are spherical, transparent and non-inhibitory.
The production of ‘seeds’ by coating somatic embryos and getting plants from these protected embryos is far from easy because:
(i) The development of these artificial seeds which are stable for many months needs physical and chemical methods for making embryo quiescent,
(ii) Such encapsulated seeds are to be protected against desiccation when stored under dry conditions.
Two systems are developed for handling of synthetic seeds:
(i) Encapsulation a gel containing nutrients is coated around somatic embryo. An encapsulation machine is developed which can produce and sort around 6,000 single embryos per hour.
(ii) Sowing the somatic embryos by fluid drilling.
Four types of synthetic seeds are proposed based on embryos and their encapsulation:
(i) Uncoated, desiccated somatic embryos e.g., for orchard grass.
(ii) Coated, desiccated somatic embryos e.g., carrot.
(iii) Encapsulated (coated), hydrated somatic embryos, e.g., alfalfa.
(iv) Uncoated hydrated embryos (in a fluid drilling gel), e.g., carrot.
Term Paper # 3.
Methods of Production of Synthetic Seeds:
Following steps are followed:
(1) Induction of pseudo-embryos (artificial embryos) from cell suspension culture.
(2) Mixing of embryos with 2% Na-alginate.
(3) Immersing the embryos in a bath of calcium salt, e.g., solution of Ca(NO3)2 for 30 min. This leads to very quick complex formation at surfaces due to exchange of ions i.e., Na+ and Ca+. As a result, individual embryo is enclosed into a clear and hardened beads of about 4 mm. Hardening of calcium alginate is modulated with concentrations of sodium alginate along with the duration of complexing. Usually 100 mM Ca2+ is used.
(4) Sieving the bead through a nylon mesh; Ca(NO3)2 solution is recycled, and
(5) Testing the growth vigour of beads by plating in sand or soil amended with pesticides.
Thus synthetic seeds are living seed-like structure derived from somatic embryoids after encapsulation by a hydrogel. Such preserved embryoids are called as synthetic seeds. These encapsulated embryos can resist unfavorable field conditions including microbial contamination, without desiccation. Such encapsulated Seeds are used as a substitute of natural seeds and can also be grown directly in the greenhouse or in the fields.
Kitto and Janick (1985) produced Citrus embryos in vitro and tested eight compounds for their synthetic coating properties on embryos. Out of these, a polyethyleneoxiue revealed good encapsulating properties, as shown with in vitro produced carrot embryos. Examples of plants produced from synthetic seeds sown in vitro and in soil include – Apium graveolens, Brassica sp., Gossypium hirsutum, Medicago sativa, Oryza sativa, Zea mays, Picea abies (in vitro), and Apium graveolens, Daucus carota, Medicago sativa (in soil).
In addition to the use of somatic embryos as propagules for encapsulation, axillary buds have also been successfully used in plants in which somatic embryogenesis is difficult to achieve, as in mulberry and other woody species. Apart from these unipolar structures (apical shoot tips and axillary shoot buds), apolar protocorms or protocorm-like bodies as well as undifferentiated embryogenic calli are also used in synthetic seed production (Table 5.2).
Synthetic seeds are produced by encapsulating the protocorm or prorocorm-like bodies in sodium alginate gel, in case of orchids like Cymbidium giganteum, Dendrobium, Phaius and Spathoglottis. Production of synthetic seeds from apical shoot tips and axillary shoot buds is facilitated by treating these organs first with auxins for root formation and then the micro-cuttings (4 mm long) are encapsulated in sodium gel.
However, no such treatment for root induction was done to encapsulated shoot buds for regenerating plants of mulberry and banana. Bacterial contamination is controlled by an antibiotic mixture (0.25 mg/l) containing cefatoxime (250 mg), rifampicin (60 mg) and tetracycline-HCL (25 mg) dissolved in 5 ml dimethyl sulphoxide. Table 5.2 lists important plant species in which synthetic seed technology has been successfully employed.
Term Paper # 4.
Recent Developments in Synthetic Seed Technology:
(1) Automate Encapsulation Method:
It is the process which in recent times fastens the production of artificial seeds. Encapsulation machine has been used successfully to encapsulate somatic embryos, as employed for alfalfa. In this method, blank alginate capsules are planted in speeding trays with the help of a vacuum seeder. These capsules are then put in the field using a Stanhay planter. To avoid rapid drying of these alginate capsules, Elvax 4260 co-polymer which acts as hydrophobic agent, is coated to help conserve embryo.
(2) Mass Balance:
This concept has improved the technology of synthetic seeds, which is based on the amount of tissue at the start of the experiment and the number of high quality plants produced at the end of the operation.
Term Paper # 5.
Commercial Production of Synthetic Seeds:
Schematic representation of stops required to produce synthetic seeds on commercial scale is illustrated as under:
Term Paper # 6.
Potential Uses of Synthetic Seeds:
(1) Reduced costs of transplants.
(2) Production of large number of identical embryos.
(3) Germplasm conservation through cryopreservation.
(4) Study of seed coat formation is possible.
(5) Usefulness in tree genetic engineering.
(6) Production of synthetic, seeds possible any time, in any season of a year.
(7) Problem of dormancy can be avoided through synthetic seed technology, thereby shortening the life cycle of a plant.
(8) It is possible to undertake study related to anatomical features of endosperm and seed coat formation.
(9) On commercial front, the encapsulated embryos can be packed on large scale with suitable pesticides, nitrogen fixing microorganisms and fertilizers.
Term Paper # 7.
Limitations of Synthetic Seed Technology:
(1) Recovery of plants from encapsulated somatic embryos is often very low, due to various reasons:
(i) Incomplete embryo formation.
(ii) Difficulties to arrest growth.
(iii) Difficulties in creating an artificial endosperm within the capsule. Hardening treatments like pre- treatment of embryogenic cultures with 12% sucrose, chilling and ABA have been described by Kitto & Janik (1985) to enhance the survival of encapsulated carrot embryos.
(2) Lack of dormancy and stress tolerance in somatic embryos limit the storage of synthetic seeds.
(3) The embryos are susceptible to microorganisms, so use of antibiotics and fungicides is recommended to check microbial contamination.
(4) Anomalous and asynchronous development of somatic embryos.
Maturation of somatic embryos which controls germination and conversion rate remains a critical factor in synthetic seed technology. Addition of high sucrose content in the medium having ABA prevents maturation, whereas PEG addition along with ABA improves frequency and synchrony of somatic embryo maturation.
Further, use of maltose and sucrose helps improve the viability and conversion rate of somatic embryos into plantlets. Another problem associated with synthetic seed technology is the diversity in the morphology of somatic embryos which eventually limits the use of somatic embryos. ABA treatment of somatic embryos leads to production of anomalous cotyledons; similarly, cytokinin treatment increases the number of somatic embryos with multiple cotyledons.
Desiccation damages the somatic embryos and inhibits their germination and conversion into plants. Besides, coating material also influences the success of the synthetic seed technology. Calcium alginate coating is very wet and sticks together, besides this; it loses water and dry down to a hard mass in a short time upon exposure to ambient atmosphere.
The other criterion affecting the synthetic seed technology is the concentration of coating material. The coat should contain nutrients and growth regulator that are necessary for germination and conversion. In this regard, sodium alginate from brown algae is the best option.
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