Varietal identificaton through grow-out test and Electrophoresis
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The document outlines the principles of varietal identification through grow-out tests and electrophoresis aimed at determining genetic purity in crops. It details procedures for conducting grow-out tests, including seed examination and observation of plant characteristics, as well as the methodology for verifying varieties using electrophoretic mobility of proteins. Key advantages and disadvantages of both techniques are provided, highlighting their effectiveness and limitations in achieving accurate varietal identification.
Varietal identificaton through grow-out test and Electrophoresis
- 1. Course no:Gpbr -314 Course title:principles of seed technology Topic:Varietal identificaton through grow- out test and Electrophoresis Submitted to: Umesh sir, Asisstant professor, Department of Genetics and plant breeding. Submitted by: K.Jyothirmai NAA/18-22 E Divya NAA/18-12 S.Beula NAA/18-07 Agri 3rd year.
- 3. Varietal Identification through Grow-out test ➢ The Main aim of grow-out test is to determine the genetic purity of the variety of the given sample. ➢ In grow-out test plant characters that are less influenced by the environment and which are highly heritable are observed by growing the plants in the field. ➢ The variety ,which is to be tested for genetic purity ,should be grown in the area for which it has been released so that the characters of that variety are fully expressed.
- 4. Sampling: The sample for grow out test are to be drawn simultaneously with the samples for other quality tests and the standa procedure shall be followed. The size of the submitted sample shall be as follows : 1000g : For maize,cotton,groundnut,soybean and species of other genera with seeds of similar size 500g : For sorghum,wheat,paddy and species of other genera with seeds of similar size. 250g : species of other genera with seeds of similar size. 100g : For bajra,jute and species of all other genera. 250 tubers: seed potato,sweet potato and other vegetatively propogat crops.
- 5. Procedure: ● Before sowing the seed in the field the seed should be examined on the diaphanoscope to identify the seeds of other variety. ● The seeds of other variety should be seperated and the percentage should be noted. ● one may also seperate the doubtful seed,which may be sown seperately for through examination. ● The various samples of the same cultivar are sown in adjacent plots with standard samples at regular intervals.
- 7. ● In case of self pollinated crops the characters are fixed and it is easy to identify the plants of other cultivars. ● In cross pollinated crops where the variability for characters is more it is essential to sow the authentic samples at regular intervals for comparison between the samples to be tested and the standard sample.
- 8. ● The sample plots should be regularly observed during the entire growing period of the crop as some of the characters are expressed at seedling stage while the others are expressed at flowering or at maturity stage. ● The size of plots,row length etc,will differ from crop to crop. ● The specifiaction for different crops are indicated in the following table.
- 10. Observations: ➔ All plants are to be studied keeping in view the distinguishing characters described for the cultivar both in the test crop as well as the control.Necessary corrections may be incorporated if the control is found to be heterogeneous. ➔ observations are made during full growing period ,or for a period specified by originating breeding Institute and deviations from the standard sample of the same variety are recorded. ➔ At suitable development stage the plots are examined carefully and plants which are obviously of other cultivar are counted and recorded.
- 11. ➔ The specifications of the field plot,row length etc,may be determined from the information given in the table. ➔ on the basis of the number of plants required for taking observations is depended on maximum permissible offtypes,which are as follows:
- 13. Advantages: ❏ It is the cheapest way to examine reasonable number of plants. ❏ It is possible to examine a large number of plots and for each plot it is possible to check large number of plants. ❏ The plants are examined during the whole period of growth.
- 14. Disadvantages: ❏ The results are not available until 4 to 12 months after the seed was received for testing.
- 15. Electrophoresis: Objective:verification of variety by electrophoretic mobility of protein on polyacrylamide gel. Principle:proteins and enzymes are the primary products of genes and hence are most suited for genetic purity determination. ● Changes in coding base sequence result in corresponding replacements in aminoacids and thus in the primary structure of protein and enzymes.
- 16. ● They possess ionizable groups and can therfore be made to exist in solution as electrically charged particles either as cations(+) or anions(-). ● Molecules with similar charge and size will have differential migration in solution with porous support medium in an electric field based upon differences in net electric charges as molecules with higher charge migrate faster than those with lower charge.
- 17. ● Particle with smaller molecular weight migrates faster than those with higher weight. ● This seperation of molecules based on their size and net electrical charge is known as electrophoresis.
- 19. Interpretation: ❖ After staining of the gel,it is placed over a trans illuminator to see the banding pattern.Relative mobility of each pattern (band) is calculated by the following formula. ❖ Relative mobility(Rm)=Distance travelled by protein ----------------------------------- Distance travelled by tracking dye
- 20. The varieties are verified on the basis of banding pattern. 1. By measuring Rm of bands 2. Total number of bands 3. presence or absence of specific band 4. Intensity of band 5. Difference in banding pattern in comparison to authentic zymogram of the variety under test.