home made DNA

“Home-made” DNA Recipe
You need: A home laboratory = a kitchen!

A blender to break cell wallsSalt to stabilize DNAWashing-up liquid (detergent) to destroy cells and nuclear membranes that protect DNAStain remover - Its enzymes deactivate all proteins which could damage DNA during the extraction processCold alcohol to precipitate DNA

Process description:
1. DNA extraction solution:- 100 ml of water
- 1 teaspoon of washing-up liquid (to help destroying membranes)
- 2 teaspoons of salt (to help extract DNA)
- add several drops (or one teaspoon of powder) of enzymatic (important!) stain remover (to destroy proteins)2. Blend a large fresh tomato using a kitchen blender. You are breaking cells now – in a lab this process is called HOMOGENIZATION.

3. In a clean drinking glass, add a few tea spoons of the blended tomatoes (try not to add chunks) to approximately 40 ml of DNA extraction solution. Mix gently.4. Put it into warm water (about 60 degrees C) for about 10 minutes. You are destroying cell membranes now.

5. Cool the mixture on ice for 5 minutes.6. Filter the mixture through coffee filter and let it drain.

7. Slowly and carefully add 20 ml of cold alcohol (should be as cold as possible – you can cool it down in a fridge or a freezer) to make a layer of alcohol floating over the filtered solution. Do not shake! Keep it on ice or in a fridge.
8. DNA will precipitate at the border of the two layers and float up to the surface.
9. You can collect the DNA with a coffee stirrer or wooden tooth-pick.10. Admire Your “Home-made” DNA! ? Did you know that:We can find DNA in all living cells.For example, a tomato contains 7 mg of DNA.We eat about 55,000,000 of cells and 1,500,000 kilometers of DNA in each meal!Bon appetite! What questions arose in you mind during the experiment? What surprised you? Why?

ASK A QUESTION!

Seed Dormancy

Seed Dormancy

Seed Dormancy Webpage What is seed dormancy and how is it related to germination? - Definition of seed dormancy(http://www.seedbiology.de/dormancy.asp)

A classification system for seed dormancy: The 'whole-seed view' Evolution of seed structure and seed dormancy

Embryo dormancy and coat dormancy: The components of physiological dormancyInduction, maintenance and release of physiological dormancy by plant hormones and environmental signalsVariation of the seed dormancy trait in Arabidopsis and Nicotiana

Seed Dormancy Webpage 2 Phylogenetic table: Seed dormancy classification with .Seed Dormancy - Related topics on other webpages Seed after-ripening: Dormancy release and promotion of germination Ecophysiology of dormancy: Response to the environment and dormancy cycling in the seedbank

Seed Germination and and Dormancy are Regulated by Light, Temperature and Plant Hormones

Seed Germination and and Dormancy are Regulated by Light, Temperature and Plant Hormones
Tobacco seed germination and class I ß-1,3-glucanase (ßGlu I) induction regulated by plant hormonesABA-sensitive ßGlu expression in the endosperm prior to endosperm rupture is widespread among Solaneceous seeds

Abscisic acid (ABA)

Gibberellins (GA)

Light / phytochrome (Pfr)Tempareturehttp://www.seedbiology.de/hormones.asp

Hormonal interactions during seed dormancy release and germinationTable:

Seed dormancy and germination of Arabidopsis hormone mutants

Ethylene and pea seed germinationEthylene-Responsive Element Binding Proteins (EREBP)Brassinosteroids and gibberellins promote tobacco seed germination by distinct pathways

SEEDSTRUCTURE

Seed Structure and Anatomy The structure, anatomy and morphology of mature seeds: an overview
The structure, anatomy and morphology of mature seeds:
model species in seed biology
Endospermic seed structure (Eudicots): Brassicaceae - Arabidopsis thaliana
ENDOSPERMICseed structure (Eudicots): Brassicaceae - Lepidium sativum
Endospermic seed structure (Eudicots): Cestroidae subgroup of Solanaceae - tobacco and other Nicotiana-
Endospermic seed structure (Eudicots): Solanoidae subgroup of Solanaceae - tomato and pepper
Endospermic seed structure (Eudicots): Euphorbiaceae - castor bean - Ricinus communisNon-endospermic seed structure (Eudicots): Fabaceae - pea and other leguminosae
Perispermic seed structure (Eudicots): Amaranthaceae - sugar beet - Beta vulgaris .
endospermic seed structure (Monocots): Alliaceae - onion
Endospermic seed structure (Monocots): Poaceae (cereal grain, caryopsis) - wheat and other cereals

SEED TESTIG (FULL INFORMATION)

CONTENTS
1.INTRODUCTIONhttp://seednet.gov.in/Material/Seed%20Testing%20Manual/Contents.pdf
2. SEED TESTING LABORATORY – LAYOUT AND FURNISHING
3. THE USE OF SEED SAMPLINGAND TESTING EQUIPMENThttp://seednet.gov.in/Material/Seed%20Testing%20Manual/Contents.pdf
4. MAINTENANCE OF EQUIPMENT
5. SEED TESTING PROCEDURE IN BRIEFhttp://seednet.gov.in/Material/Seed%20Testing%20Manual/Contents.pdf
6. SAMPLING OF SEEDS FOR TESTING
7. RECEIVING SAMPLES AND INITIAL TESTS
8. PURITY ANALYSIShttp://seednet.gov.in/Material/Seed%20Testing%20Manual/Contents.pdf
9. SEED GERMINATIONhttp://seednet.gov.in/Material/Seed%20Testing%20Manual/Contents.pdf
10. RAPID TESTS FOR VIABILITYhttp://seednet.gov.in/Material/Seed%20Testing%20Manual/Contents.pdf
11. OBTAINING REPRODUCIBLE RESULTS AND USING
TOLERANCES
12. VISUAL AIDS FOR DEVELOPING JUDGEMENT
13. REPORTING THE RESULTS OF TESTS
14. STORAGE OF TEST SAMPLES
15. THE USE AND MAINTENANCE OF RECORDS AND FILES
16. PERSONNEL AND STAFFINGhttp://seednet.gov.in/meterial
17. FIELD TESTS
18. THE PLACE OF RESEARCH IN SEED TESTING
19. THE ROLE OF THE SEED TESTING LABORATORIES UNDER THE
SEED LAW

SEED TESTING METHOD FOR TRITICUM SPP.

Crop: Triticum spp (Wheat) http:///www.seedtest.org/upload/cms/user/7-014.pdf
Pathogen: Stagonospora nodorum Berk. = syn Septoria nodorum Berk., Perfect state: Leptosphaeria nodorum Mailer
Method Abstract
This method was originally published in the ISTA Handbook of Seed Health Testing in November 1964 as S.3. No. 19 and revised in 1984 by M. Kietreiber, Bundesanstalt für Pflanzenbau, Wien, Austria. The method was incorporated into the newly revised Annexe to Chapter 7 in 2002 from the 1999 edition of the ISTA Rules. The method was reviewed by the ISTA-Seed Health Committee in 2006 (Cockerell & Koenraadt, 2007) with the recommendation to accept for a further five years.
Summary of Validation Study:
Studied in International Comparative Testing: 1959, 1961, 1962, 1964 and 1979-81
Using potato dextrose in darkness, Hewett (1975) found a correlation coefficient of 0.95 between counts in the laboratory and the number of diseased seedlings in the field. Comparative tests organized by the ISTA Plant Disease Committee gave reasonable agreement between stations (Rennie, 1982).
International Rules for Seed Testing Effective from 1 January 2008
7-014: Detection of Septoria nodorum on Triticum aestivum (Wheat)
Annexe to Chapter 7: Seed Health Methods: 7-014-3
Safety Precautions
Ensure you are familiar with hazard data and take appropriate safety precautions, especially during preparation of media, autoclaving and weighing out of ingredients. It is assumed that this procedure is being carried out in microbiological laboratory by persons familiar with the principles of Good Laboratory Practice, Good Microbiological Practice, and aseptic technique. Dispose of all waste materials in an appropriate way (e.g. autoclave, disinfect) and in accordance with local safety regulations.
Treated Seed
This method has not been validated for the determination of Septoria nodorum on treated seed. Seed treatments may affect the performance of the method.
(Definition of treatment: any process, physical, biological or chemical, to which a seed lot is subjected, including seed coatings. See 7.2.3)
Materials
Reference Material
The use of reference cultures or other appropriate material is recommended when ever possible.
Media
Malt Agar or Potato Dextrose Agar containing 100 ppm streptomycin sulphate.
Sodium hypochlorite solution
(1% available chlorine) for seed disinfection.
Petri dishes
When sowing density is given by a number of seeds per Petri dish, a diameter of 90 mm is assumed.
Incubator
Capable of operating in the range 20 ± 2 ºC.
Sample Preparation
The test is carried out on a working sample of 400 seeds as described in Section 7.4.1 of the International Rules for Seed Testing.
Method
1. Pretreatment
10 minutes in 1% (avilable chlorine) sodium hypochlorite.
2. Agar method
Malt agar or Potato Dextrose Agar containing 100 ppm streptomycin sulphate.
3. Incubation
7 days at 20 ºC in darkness.
4. Examination.
After 7 days examine each seed by naked eye for slow-growing circular colonies of dense white or cream mycelium that often covers infected seeds. The reverse of the colony is yellow/brown becoming darker with age. International Rules for Seed Testing Effective from 1 January 2008 7-014: Detection of Septoria nodorum on Triticum aestivum (Wheat) Annexe to Chapter 7: Seed Health Methods: 7-014-4
General Methods (common to many test procedures)
1. Checking tolerances
Tolerances provide a means of assessing whether or not the variation in result within or between tests is sufficiently wide as to raise doubts about the accuracy of the results. Suitable tolerances, which can be applied to most direct seed health tests, can be found in Tables 5B of Chapter 5 of the ISTA Rules, or in the Handbook of Tolerances and Measures of Precision for Seed Testing by S.R. Miles (Proceedings of the International Seed Testing Association 28 (1963) No 3, p 644).
2. Reporting Results
The result of a seed health test should indicate the scientific name of the pathogen detected and the test method used. When reported on an ISTA International Seed Analysis Certificate, results are entered under Other Determinations.
Preparation of Media and Solutions
1. Sodium Hypochlorite Solution
Sodium hypochlorite for pretreatment of seed can be prepared from commercial bleach diluted to 1% available chlorine. The concentration of chlorine in commercial bleach varies considerably. Use the formula Vstock = Vfinal x Cfinal / Cstock (where V= volume and C= % available chlorine) to calculate the volume of commercial bleach stock solution required to prepare sodium hypochlorite solutions for use in seed pretreatment.
To prepare a 1 liter solution of sodium hypochlorite containing 1% chlorine from a stock of commercial bleach containing 12% available chlorine:
Vstock = Vfinal x Cfinal / Cstock Vstock = 1 x 1/12 = 0.083
Thus add 83 mL of the 12% stock to 917 mL water.
2. Malt Agar
Compound
g/L
Malt Agar1
According to manufacturer's instructions
Distilled/de-ionized water
1000 mL
Streptomycin sulfate
1 mg
CCP 1 Malt agar constituents should be equivalent to those of the following manufacturers Difco, USA or Oxoid, UK.
Preparation
1. Weigh out ingredients into a suitable autoclavable container.
2. Add 1000 mL of distilled/de-ionized water.
3. Dissolve powdered Malt Agar in distilled/de-ionized water by stirring.
4. Autoclave at 15 p.s.i. and 121 °C for 15 min.
5. Allow agar to cool to approx. 50 °C.
6. Pour 15–22 mL of molten agar into 90 mm Petri plates and allow to solidify before use. International Rules for Seed Testing Effective from 1 January 2008 7-014: Detection of Septoria nodorum on Triticum aestivum (Wheat) Annexe to Chapter 7: Seed Health Methods: 7-014-5
Storage
Prepared plates may be stored at 4 ºC for up to 6 weeks.
Potato Dextrose Agar
Compound
g/L
Potato Dextrose Agar1
According to manufacturer's instructions
Distilled/de-ionized Water
1000 mL
Streptomycin sulphate
1 mg
CCP 1 PDA constituents should be equivalent to those of the following manufacturers Difco, USA or Oxoid, UK.
Preparation
1. Weigh out ingredients into a suitable autoclavable container.
2. Add 1000 mL of distilled/de-ionized water.
3. Dissolve powdered PDA in distilled/de-ionized water by stirring.
4. Autoclave at 15 p.s.i. and 121 °C for 15 min.
5. Allow agar to cool to approx. 50°C.
6. Pour 15–22 mL of molten agar into 90 cm Petri plates and allow to solidify before use.
Storage
Prepared plates may be stored at 4 ºC for up to 6 weeks.
Quality Assurance
Critical Control Points
Where the wording of the original Working Sheet suggests that an action is critical this has been marked with CCP.
References
The following references are extracted from the ISTA Handbook on Seed Health Testing, Working Sheet No. 19, M. Kietreiber, 1984.
Hewett, P.D. (1975). Septoria nodorum. Seedlings and stubble of winter wheat. Transactions of British Mycological Society, 65, 7-18.
Kietreiber, M. (1961). Die Erkennung des Septoria-Befalles von Weizenkornern

SEED TESTING METHOD FOR DAUCUS CAROTA

Crop: Daucus carota (carrot)
Pathogen: Alternaria dauci
.Background
This method was originally published in the ISTA Handbook of Seed Health Testing in
November 1964 as S.3. No. 4 and revised in 1987 (Gambogi, 1987). Safety Precautions
Ensure you are familiar with hazard data and take appropriate safety precautions. It
is assumed that this procedure is being carried out in a microbiological laboratory by
persons familiar with the principles of Good Laboratory Practice, Good Microbiological
Practice, and aseptic technique. Dispose of all waste materials in an appropriate way
(e.g. autoclave, disinfect) and in accordance with local health, environmental and safety
regulations.
Treated seed
Seed treatments may affect the performance of this test. It should only be performed on
untreated seed.
Materials
Reference material - The use of reference cultures or other appropriate material is
recommended.
Substrate - Blotters or fi lter papers, 9.0 cm, circular (e.g. Whatman No
1 or equivalent), free from micro-organisms and inhibitors (3
per plate).
Plates - 9.0 cm sterile Petri dishes (one per ten seeds).
Incubator - Operating at 20 ± 2°C, equipped with timer-controlled nearultraviolet
lights (NUV, peak at 360 nm, e.g. colour number
08, Philips; BLB, Sylvania).
Freezer - Operating at –20 ± 2°C.
Sample Preparation
1. It is vital to exclude any possibility of cross-contamination between seed samples.
This can be achieved by swabbing/spraying equipment and gloved hands with 70%
ethanol.
2. The test is carried out on a working sample as described in Section 7.4.1 of the
International Rules for Seed Testing.
Method
[Critical control points are indicated by CCP]
1. Place three 9.0 cm fi lter papers in each plate and soak with sterile distilled/de-ionised
water. Drain away excess water.
2. Aseptically place 10 seeds, evenly spaced (CCP), on the surface of the fi lter paper in
each plate.
3. Incubate for 3 d at 20 ± 2°C in the dark.
4. Transfer plates to freezer and maintain at –20 ± 2°C for 24 h.
5. After freezing, incubate for 6 d at 20 ± 2°C with alternating 12 h periods of darkness
and NUV light (ISTA,1984; Tempe, 1968). Plates should be approx. 25 cm below the
lights and should not be stacked.
6. Examine seeds under a stereoscopic microscope at x30 for fungal growth and up
to x80 magnifi cation for identifi cation of conidia. Conidiophores are simple or slightly
branched (Fig. 1), arising singly or in small groups from the surface of the seed or on
aerial mycelium. Conidia are usually solitary, obclavate, up to 450 μm long (including
beak), pale olivaceous brown at fi rst, becoming brown with age, with a long pale
Annexe to Chapter 7: Seed Health Methods: 7-001a-4
International Rules for Seed Testing Effective from 1st January 2003
7-001a (2003): Alternaria dauci on Daucus carota (Blotter)
beak up to 3 times the length of the body (Ellis, 1971). Groups of sunken conidia are
sometimes visible by the emerging clusters of their bright long beaks (Fig. 1, bottom
left). Record the number of infected seeds in each plate (CCP).
General Methods
1. Checking Tolerances
Tolerances provide a means of assessing whether or not the variation in result within or
between tests is suffi ciently wide as to raise doubts about the accuracy of the results. A
tolerance table, which can be applied to most direct seed health tests, can be found in
Table 5.1 of Annexe 16 of the International Rules for Seed Testing or in Table G1 of the
Handbook of Tolerances and Measures of Precision for Seed Testing (Miles, 1963)
2. Reporting Results
The result of a seed health test should indicate the scientifi c name of the pathogen,
and the test method used. When reported on an ISTA Certifi cate, results are entered
under Other Determinations.
In the case of a negative result (pathogen not detected), the results should be
reported in terms of the tolerance standard (e.g. infection level less than 1% with 95%
probability). The tolerance standard depends on the total number of seeds tested, n,
and is approximately 3/n (P=0.95) (see Roberts et al., 1993).
In the case of a positive result the report should indicate percentage of infected
seeds.
Quality Assurance
Specifi c Training
This test should only be performed by persons who have been trained in fungal
identifi cation or under the direct supervision of someone who has.
Critical Control Points
[identifi ed by CCP in the methods]
Spreading hyphae may lead to contamination of other seeds. Seeds must therefore be
spaced at least 20 mm from each other with not more than 10 seeds per 9.0 cm Petri dish
(Step 2).
Samples may be diffi cult to examine due to the growth of contaminants, especially
Alternaria tenuis, and/or A. radicina. Experience and great care is required for the
detection of all occurrences (ISTA 1984) (Step 6).
Supplementary examination may be required 13-14 d after plating of seeds to allow
hampered or deeper inoculum to exceed contaminants by its fructifi cation (Hewett, 1964)
(Step 6)

SEED TESTIG METHODS

International Rules for Seed Testing Effective from 1 January 2008
7-010: Detection of Drechslera oryzae on Oryza sativa (Rice)
Seed Health Methods: 7-010-2
Crop: Oryza sativa (Rice)
Pathogen: Drechslera oryzae (Breda de Haan) Subram. & Jain, Cochliobolus miyabeanus (Ito & Kurib.) Drechsler ex Dastur [teleomorph] syn. Ophiobolus miyabeanus Ito & Kuribayashi, Bipolaris oryzae (Breda de Haan) Shoem., Helminthosporium oryzae Breda de Ha
Background
This method was originally published in the ISTA Handbook of Seed Health Testing in November 1964 as S.3. No. 11. The method was incorporated into the newly revised Annexe to Chapter 7 in 2002 from the 1999 edition of the ISTA Rules. The method was reviewed by the ISTA-Seed Health Committee in 2006 (Cockerell & Koenraadt, 2007) with the recommendation to accept for a further five years.
Safety Precautions
Ensure you are familiar with hazard data and take appropriate safety precautions, especially during preparation of media, autoclaving and weighing out of ingredients. It is assumed that this procedure is being carried out in microbiological laboratory by persons familiar with the principles of Good Laboratory Practice, Good Microbiological Practice, and aseptic technique. Dispose of all waste materials in an appropriate way (e.g. autoclave, disinfect) and in accordance with local safety regulations.
Treated Seed
This method has not been validated for the determination of Drechslera oryzae on treated seed. Seed treatments may affect the performance of the method.
(Definition of treatment: any process, physical, biological or chemical, to which a seed lot is subjected, including seed coatings. See 7.2.3)
Materials
Reference Material
-
The use of reference cultures or other appropriate material is recommended when ever possible.
Media
-
Blotters (filter paper)
Petri dishes
-
When sowing density is given by a number of seeds per Petri dish, a diameter of 90 mm is assumed.
Incubator
Capable of operating in the range 22 ± 2 ºC. To stimulate sporulation, alternating 12 h periods of darkness and near-ultraviolet light (NUV) during incubation are recommended. The recommended source is the black light fluorescent lamp (peak at 360 nm) but daylight fluorescent tubes are satisfactory.
Sample Preparation
The test is carried out on a working sample of 400 seeds as described in Section 7.4.1 of the ISTA Rules.
Method
1. Pretreatment
None
2. Blotter
On water-soaked blotters in Petri dishes. Place 25 seeds in each dish.
3. Incubation
7 days at 22 ºC in NUV in 12 h light/12 h dark cycle.
4. Examination
Examine each seed at ×12–50 magnification for conidia of D. oryzae. Conidiophores of the fungus are produced on the seed coat and also on light grey aerial mycelium covering whole or part of the seed, giving a fluffy appearance. The fungus may occasionally spread on to the blotters. In doubtful cases confirmation may be made by International Rules for Seed Testing Effective from 1 January 2008 7-010: Detection of Drechslera oryzae on Oryza sativa (Rice) Annexe to Chapter 7: Seed Health Methods: 7-010-4
examining conidia at ×200 magnification. Conidia are crescent-shaped 35–107 μm × 11–17 μm (Fig. 1) light brown to brown, widest in the middle or below the middle and tapering to rounded ends.
General Methods (common to many test procedures)
1. Checking tolerances
Tolerances provide a means of assessing whether or not the variation in result within or between tests is sufficiently wide as to raise doubts about the accuracy of the results. Suitable tolerances, which can be applied to most direct seed health tests, can be found in Tables 5B of Chapter 5 of the ISTA Rules, or in the Handbook of Tolerances and Measures of Precision for Seed Testing by S.R. Miles (Proceedings of the International Seed Testing Association 28 (1963) No 3, p 644).
2. Reporting Results
The result of a seed health test should indicate the scientific name of the pathogen detected and the test method used. When reported on an ISTA International Seed Analysis Certificate, results are entered under Other Determinations.
Quality Assurance
Critical Control Points
None listed
References
The following references are extracted from the ISTA Handbook on Seed Health Testing, Working Sheet No. 11, 1964.
Azeemudin, Soraya and Ponchet, J., (1961): Isolement de Piricularia oryzae (Br. Cav.) et de Helminthosporium oryzae Breda de Haan à partir de semences de riz Oryza sativa L. Annis. Epiphyt. 12, 141-147.
Neergaard, P. and Saad, A., (1962): Seed health testing of rice. A contribution to

Bt cotton
Cotton and other monocultured crops require an intensive use of pesticides as various types of pests attack these crops causing extensive damage. Over the past 40 years, many pests have developed resistance to pesticides.
So far, the only successful approach to engineering crops for insect tolerance has been the addition of Bt toxin, a family of toxins originally derived from soil bacteria. The Bt toxin contained by the Bt crops is no different from other chemical pesticides, but causes much less damage to the environment. These toxins are effective against a variety of economically important crop pests but pose no hazard to non-target organisms like mammals and fish. Three Bt crops are now commercially available: corn, cotton, and potato.
As of now, cotton is the most popular of the Bt crops: it was planted on about 1.8 million acres (728437 ha) in 1996 and 1997. The Bt gene was isolated and transferred from a bacterium bacillus thurigiensis to American cotton. The American cotton was subsequently crossed with Indian cotton to introduce the gene into native varieties.
The Bt cotton variety contains a foreign gene obtained from bacillus thuringiensis. This bacterial gene, introduced genetically into the cotton seeds, protects the plants from bollworm (A. lepidoptora), a major pest of cotton. The worm feeding on the leaves of a BT cotton plant becomes lethargic and sleepy, thereby causing less damage to the plant.
Field trials have shown that farmers who grew the Bt variety obtained 25%–75% more cotton than those who grew the normal variety. Also, Bt cotton requires only two sprays of chemical pesticide against eight sprays for normal variety. According to the director general of the Indian Council of Agricultural Research, India uses about half of its pesticides on cotton to fight the bollworm menace.
Use of Bt cotton has led to a 3%–27 increase in cotton yield in countries where it is grown.

For more information on Bt cotton link to
http://www.ag.auburn.edu/aaes/information/highlights/summer00/btcotton.html

Seed Technology
Seeds are the delivery systems for agricultural biotechnology. High quality seed leads to excellent seedling performance in the field. It is the ultimative basis of successful companies that breed crop plants for seed production. Seed quality is a complex trait that is determined by interactions between multiple genetic factors and environmental conditions. Modern approches to improve seed quality therefore combine classical genetics, plant molecular biology and a variety of seed technologies. These "seed biotechnologies" enhance physiological quality, vigor and synchronity to establish a crop in the field under diverse environmental conditions. Seed technologies (seed enhancements, seed treatments) include priming, pelleting, coating, artificial seeds, and other novel seed treatment methods of applied seed biology. Our basic and applied seed research projects focus on embryo growth and on the different seed covering layers (e.g. testa, endosperm, pericarp), which are determinants of seed quality and exhibit the biodiversity of seed structures. Seed germination is controlled by environmental factors (light, temperature, water) and on plant hormones as endogenous regulators (gibberellins, abscisic acid, ethylene, auxin, cytokinins, brassinosteroids). The utilization of plant hormones and inhibitors of their biosynthesis and action in seed treatment technologies affects seed germination and seedling emergence. The genes, enzymes, signaling components and down-stream targets of plant hormones provide molecular marker for seed quality and seedling performance.Dormancy of crop and horticultural seeds is an unwanted trait for horticulture. However, a certain degree of dormancy is required to prevent viviparous germination on the plant, e.g. preharvest sprouting of cereal crops. Applied aspects of the control of germination by seed dormancy are the topic of chapter III.5 of the review "Seed dormancy and the control of germination" by Finch-Savage and Leubner-Metzger (2006). A separate supplementary file of chapter III.5 is available - download PDF file 128 KB Mechanical seed enhancementsSeed coating and pelleting Seed priming and pregerminated seedArtificial seedMolecular farming using seeds as hostsHyperlinks, reviews and book chapters on seed technologies
Mechanical seed enhancements The methods to improve seed quality by mechanical techniques include polishing off or rubbing off seed coat (testa) or fruit coat (pericarp) projections or hairs ('abgeriebenes Saatgut'), sorting into defined seed size classes or sorting by seed density. Examples:Seeds of horticultural species like in the image next to this text. © Ernst Benary Samenzucht GmbH - http://www.benary.de Sugar beet fruits, where polishing removes projections of the pericarp/perianth, which is followed by sorting into defined seed size classes.
Seed coating and pelleting Important methods to enhance seed and seedling performance are through addition of chemicals to protect the seed from pathogens and/or to improve germination. Different techniques of seed coating ('Saatgutbeschichtung') and seed pelleting ('Pillierung') are used for this. The image below shows a film-coated sugar beet fruit (left) and a pelleted plus film-coated sugar beet fruit (right). The image on the right shows such film-coated and orange-colored sugar beet pellets of a seed company (© KWS SAAT AG - http://www.kws.de).
Film-coating methods allow the chemicals to be applied in a synthetic polymer that is sprayed onto the seeds and provide a solid, thin coat covering them. The advantage of the polymers is that they adhere tightly to the seed and prevent loss of active materials like fungicides, nutrients, colorants or plant hormones. Some novel applications of film coating are used to modify imbibition and germination. They can confer temperature-sensitive water permeability to seeds or affect gaseous exchange. By this they control the timing of seed germination and seedling emergence. Certain temperature-dependent water-resistant polymers can delay imbibition until the climatic conditions become suitable for continued seedling growth.Seed pelleting adds thicker artificial coverings to seeds, which can be used to cover irregular seed shapes and add chemicals to the pellet matrix, e.g. of sugar beet or vegetable seeds. The pellet matrix consists of filling materials and glue. Loam, starch, tyllose (cellulose derivative) or polyacrylate/polyacrylamide polymers are commercially used. A film coat can be added onto the pelleting layer as shown in the figure above. Seed pelleting is also used to increase the size of very small horticultural seeds. This provides improved planting features, e.g. singulate planting, the use of planting machines, or precise placement and visibility in/on the soil. The images below this text are examples for pelleting of very small horticultural seeds. © Ernst Benary Samenzucht GmbH - http://www.benary.de
Seed priming and pregerminated seedSeed priming is the most important physiological seed enhancement method. Seed priming is an hydration treatment that allows controlled imbibition and induction of the pregerminative metabolism ("activation"), but radicle emergence is prevented. The hydration treatment is stopped before dessication tolerance is lost. An important problem is to stop the priming process in the right moment, this time depends on the species and the seed batch. Molecular marker can be used to control the priming process. Priming solutions can be supplemented with plant hormones or beneficial microorganisms. The seeds can be dried back for storage, distribution and planting. Germination speed and synchronity of primed seeds are enhanced (see figures below) and can be interpreted in the way that priming increases seed vigor (short or no "activation" time). A wider temperature range for germination, release of dormancy and faster emergence of uniform seedlings is achieved. This leads to better crop stands and higher yields. A practical drawback of primed seeds is often a decrease in storability and the need for cool storage temperatures.
Several types of seed priming are commonly used: Osmopriming (osmoconditioning) is the standard priming technique. Seeds are incubated in well aerated solutions with a low water potential, and afterwards washes and dried. The low water potential of the solutions can be achieved by adding osmotica like mannitol, polyethyleneglycol (PEG) or salts like KCl. Hydropriming (drum priming) is achieved by continuous or successive addition of a limited amount of water to the seeds. A drum is used for this purpose and the water can also be applied by humid air. 'On-farm steeping' is the cheep and useful technique that is practized by incubating seeds (cereals, legumes) for a limited time in warm water. Matrixpriming (matriconditioning) is the incubation of seeds in a solid, insoluble matrix (vermiculite, diatomaceous earth, cross-linked highly water-absorbent polymers) with a limited amount of water. This method confers a slow imbibition. Pregerminated seeds is only possible with a few species. In contrast to normal priming, seeds are allowed to perform radicle protrusion. This is followed by sorting for specific stages, a treatment that reinduces dessication tolerance, and drying. The use of pregerminated seeds causes rapid and uniform seedling development.
Artificial సీడ్ cellculture and regeneration techniques allow the mass production of somatic embryos. This can be used to generate genetically identical seedlings of poplar, orchids and other species. Somatic embryos can be packed in a suitable gel-type matrix (agar-agar, gums, dextrans) and covered with an artificial seed coat. These artificial seeds provide an important packaging system. Figure from "Artificial Plant Seed Production - Singapore Polytechnic School of Chemical & Life Sciences - © Wendy Shu (Lecturer, School of Chemical & Life Sciences)"
Molecular farming using seeds as;The concept of using plants as hosts for the production of valuable proteins has been called "molocular farming". A wide range of pharmacologically interesting proteins can be expressed in diverse plant organs. A very interesting possibility is to use seeds as a host for molecular farming. This has as an advantage that these transgenic seeds harboring the protein of interest can be stored in the dry state for a long time and the integrity of the pharmacologically interesting protein is kept. Modified seed storage proteins or modified oleosin proteins have been used for this purpose. Seed-specific gene expression is being exploited in applications including the production of proteins of pharmaceutical or industrial interest in seeds. A very interesting technology is based on the genetic manipulation or physical manipulation of plant seed oilbodies (Brassica, Arabidopsis). Oilbodies are protein-coated lipospheres that naturally form in plant seeds to function in triglyceride (oil) storage. The lab of Maurice M. Moloney (University of Calgary, Canada) has performed interesting research on this. Several reviews of M. Moloney (see below) describe these approaches and can be found on his lab website. The company SemBioSys Genetics Inc. has developed proprietary technologies based on both transgenic and non-transgenic oilbodies. The transgenic technology is based on the genetic engineering of oilbodies and oilbody-associated proteins, or oleosins. The company website offers information about the technology and publications related to it.