Presentation on Mutation breeding for Oligogenic and Polygenic Traits.pptx

This presentation provides an in-depth exploration of mutation breeding, a technique used to develop new crop varieties with enhanced traits such as yield, disease resistance, and nutritional value. It covers both oligogenic and polygenic traits, highlighting the principles, methods, and applications of mutation induction through physical, chemical, and gene editing techniques. The presentation outlines the procedural steps in mutation breeding, from the selection of objectives and plant parts to mutagen treatment and screening/selection of mutants. It also discusses the advantages, disadvantages, and challenges associated with mutation breeding, emphasizing its role in sustainable agriculture and food security

1. Presentation on: Mutation Breeding for Oligogennic and Polygenic Traits Presented by Ganesh raj joshi Roll. No: 04 8 th semester, B.sc Ag GAASC, Baitadi , Nepal

2. Introduction Mutation Sudden heritable change in a characteristic of an organism not due to segregation and recombination Mutation is of two types: Natural or spontaneous and artificial or induced Mutation Breeding The creation of mutations and their utilization for the production of new superior varieties is known as mutation breeding This method has been instrumental in developing new crop varieties with enhanced yield, disease resistance, nutritional value, and other desirable traits

3. Oligogenic traits and polygenic traits Oligogenic traits Oligogenic traits are controlled by a small number of genes, typically two to five These traits often exhibit a clear-cut inheritance pattern, making them relatively easier to target in mutation breeding Examples of oligogenic traits include disease resistance, seed size, and flowering time Polygenic traits Polygenic traits are controlled by multiple genes, often interacting in complex ways These traits are typically more challenging to modify through mutation breeding due to their complex genetic basis .Examples of polygenic traits include yield, plant height, and nutritional content

4. Principles of Mutation Induction

5. Procedure of Mutation Breeding

6. Contd ….

7. 7. Screening/ selection Mainly three types of selection techniques are used in M1 and subsequent generation

8. Mutation breeding for oligogenic traits -------------------- -------------------- --------------------- Treated seeds are spaced-planted Seeds from the M1 plants are harvested separately to raise M2 progeny 1 st year M1 2 nd year M2 Individual plant progenies are grown in rows Seeds from all the plants of each row containing or suspected to contain the mutant allele harvested separately 3 rd year M3 Individual plant progenies rows are grown Superior mutant lines harvested in bulk if they are homogeneous In heterogeneous progenies, individual plants may be selected

9. PYT is conducted using a suitable check Superior mutant lines are selected for replicated multilocation trials 4 th year M4 5 th -7 th year M5-7 Replicated yield trial at several location Outstanding line released as a new variety 8 th year M8 Seed multiplication for distribution among farmers _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Fig: A generalized scheme for mutation breeding for oligogenic trait Contd …

10. Mutation breeding for polygenic traits M1- M2 M1 and M2 are grown in the same way as in the case og oligogenic traits In M2, vigorous, fertile, and normal-looking plants that do not exhibit a mutant phenotype are selected and their seeds are harvested separately to raise individual plant progeny rows in M3 M3 Progeny rows from individual selected plants selected Careful observations are made on M3 rows for small deviations in phenotype from the parent variety Inferior rows are discarded Homogenous progenies are harvested in bulk

11. Contd … M4 Seeds from homogeneous M3 rows are planted in a preliminary yield trail with a suitable check Progenies showing segregation may be subjected to selection only if they are promising Superior progenies sre selected and harvested in bulk for preliminary yield tests in M5 M5-M8 Myultilocation trials are conducted Outstanding progenies are released as new varieties

12. Application of mutation breeding 1. Increased Yield Mutation breeding has been used to develop crop varieties with higher yield potential, contributing to food security and sustainable agriculture 2. Disease Resistance Mutations have been introduced to enhance disease resistance in various crops, reducing crop losses and minimizing the need for pesticides 3. Improved Quality Mutation breeding has led to improvements in crop quality, including enhanced nutritional value, flavor, and storage properties

13. Advantages Disadvantages It is a cheap and rapid method for developing new varieties It often breaks undesirable gene linkage Mutation breeding is the simple, quick, and best way for a new character is to be induced It is more effective for the improvement of oligogenic characteristics such as disease resistance The frequency of desirable mutation is shallow, about 0.1% of total mutations The breeder has to screen a large population to select a desirable mutation There may be problems in the registration of mutant variety in many parts Most of the mutations are recessive and their side effects are not expressed

14. Challenges in Mutation Breeding Unpredictability Mutations can occur randomly throughout the genome, making it difficult to predict the exact outcome of mutation breeding. This can lead to unintended changes and require extensive screening efforts to identify desirable mutations 2. Public Perception There may be public concerns regarding the safety and ethical implications of using mutations in food production. Addressing these concerns and ensuring transparency in research and development is crucial for public acceptance