Study of germplasm of various crops 1.pptx

Germplasm collection

1. STUDY OF GERMPLASM OF VARIOUS CROPS Dr Akanksha Tiwari Assistant Professor (GPB) College of Agriculture, Azamgarh

2. Introduction Germplasm= Germ Cell + collectively Total genetic material present in any species. Germplasm is a living tissue from new plant can be grown . It can be a seed or another plant part. Germplasm contain the information for a specific genetic makeup. It can be defined as all the alleles of various genes, present in a crop species and its wild relatives. Germplasm is also termed as genetic resources

3. Classification of Genetic resources Genetic resources can be broadly grouped into two types (Based on domestication) 1. cultivated germplasm 2. wild germplasm Alternatively, they termed as (Based on their place of origin) 1. indigenous (from the country in question) 2. exotic (from another country)

4. Cont.. Land races: these are primitive varieties which was evolved over centuries or even millenia through both natural and artificial selection but without systematic and sustained plant breeding effort. Obsolate varieties : these varieties were developed by systematic breeding effort, were once commercially cultivated, but are no more grown Varieties in cultivation : Botanically a variety is a sub group of a species. These varieties have been evolved through planned plant breeding According to seed act (1966, sub section 16 of section 2) it is a sub division of a kind identified by its growth, yield, plant, fruit, seed or other characters.

5. Breeding lines : These lines/population developed in breeding programmes , have narrow genetic base and often contain valuable gene combinations. Eg . Mutant lines, transgenic lines Special genetic stocks : This category includes lines carrying gene mutations, chromosomal aberrations, marker genes etc. eg . Monosomic lines, trisomic lines. Wild forms and wild relatives : Wild forms are the wild species from which crop species were directly derived. They are easy to cross with the concerned crop species. The wild relatives include all other species, which are related to the crop species by descent during their evolution. Wild relatives are much more difficult to hybridize with crops than are the wild forms.

6. Exploration Exploration refers to collection trips and collection refer to tapping of genetic diversity from various sources and assembling the same at one place. The exploration and collection is a highly scientific process.This process takes into account six important items, viz ,( 1)sources of collection ,( 2) priority of collection ,(3 ) agencies of collection, ( 4)methods of collection ,(5 ) methods of sampling and (6 ) sample size. Merits Collection helps in tapping crop genetic diversity and assembling the same at one place . It reduces the loss of genetic diversity due to genetic erosion . Sometimes we get material of special interest during exploration trips . Collection also helps in saving certain genotypes from extinction . Demerits   Collection of germplasm especially from other countries, sometimes leads to entry of new diseases , new insects and new weeds . Collection is a tedious job . Collector , sometimes has encounter with wild animals like elephants,tigers etc . Transportation of huge collections also poses difficulties in the exploration and collection .

7. Germplasm collections A germplasm collection of a crop species consists of a large number of lines, varieties and related wild species of a crop. Such collections are also called gene banks . World collection : when a germplasm collection is sufficiently large to include entries or accessions from all over the world, it is called world collection

8. Germplasm world collection crop Senegal Groundnut Beltsville, USA Small grain crops Cambridge, U.K. Potato Florida Sugarcane Ethiopia, Africa Coffee New Zealand Sweet potato

9. S.No . Institutions 1 Central Institute for Cotton Research, Nagpur 2 Central Plantation Crops Research Institute, Kasargod 3 Central Potato Research Institue , Shimla 4 Central Tobacco Research Institure , Rajahmundry 5 Central Tuber Crop Research Institue , Thiruvanantpuram 6 NRRI (National Rice Research Institute), Cuttak 7 Directorate of Oilseeds Research, Hyderabad 8 Directorate of Wheat Reasearch , Karnal 9 Project Directorate on Maize, New Delhi 10 Indian Grassland and Fodder Research Institute, Jhansi 11 Indian Institute of Horticultural Research, Banalore 12 Indian Institute of Pulses Research, Kanpur 13 Sugarcane Breeding Institute, Coimbatore 14 Indian Institute of Vegetable Research, Varanasi 15 National Research Centre for Groundnut, Junagarh 16 National Research Centre for Soybean, Indore 17 National Research Centre for Sorghum, Hyderabad

10. Activities in Germplasm Conservation

11. Germplasm conservation Germplasm has to be maintained in such a state that minimizes the risk of its loss and allows either its direct planting in the field or its preparation for planting with relative ease; this is called germplasm conservation. In situ conservation Ex situ conservation

12. In situ conservation Conservation of germplasm in its natural habitat or in the area where it grows naturally is known as in situ germplasm conservation. This is achieved by protecting this area from human interference; such an area is called natural park, biosphere reserve or gene sanctuary. A gene sanctuary is best located within the centre of origin of the crop species concerned.

13. Ex situ conservation Conservation of germplasm away from its natural habitat is called ex situ germplasm conservation. It can be achieved in the following five ways: 1. seed gene bank 2. plant or field gene bank 3. Shoot tip gene banks 4. Cell and organ gene banks 5. DNA gene banks

14. Roberts (1973) Classified seeds into two major groups: 1. Orthodox seed : seeds of this type can be dried to a moisture content of 5% or lower without lowering their viability. Such seeds can be easily stored for long periods 2. Recalcitrant seeds : viability of this group of seeds drops drastically if their moisture content is reduced below 12-30% Eg. Seeds of many forest and fruit trees like citrus, coffee, rubber, mango, jackfruit Such seeds present considerab;e difficulties in storage.

15. Classification of seed bank collections 1. Base collections : germplasm of a crop stored at -20oC with 5 % moisture content. They are disturbed only for regeneration and germination test. 2. Active collection : the germplasm in active collection are stored at temperature below 15oC and the seed moisture is kept at 5%. These collections are used for evaluation, multiplication and distribution. 3. Working collection : seeds of these accessions are stored for 3-5 years at less the 15oC and usually about 10% moisture. The accessions being actively used in crop improvement programme .

16. Core collection The concept of core collection was proposed by Frankel . It refers to a subset of base collection which represents the large collection. Or a limited set of accessions derived from an existing germplasm collections .

17. GENE POOL

18. Concept of gene pool was proposed by Harlan and De Wet in 1971. Gene pool consists of all the genes and their alleles present in all such individuals, which hybridize or can hybridize with each other. Classification of Gene pool 1. Primary (GP 1) 2. Secondary (GP 2) 3. Tertiary (GP 3)

19. 1. Primary gene pool (GP1):  Members of the primary gene pool include the same species or closely related species which produce completely fertile offspring on inter-mating. Crossing between a member of GP1 is very easy. The resulting hybrids are vigorous and show normal meiotic chromosome pairing and recombination. There is normal gene segregation, and seed fertility is complete. Members of this group are the most commonly used in breeding programs.      2. Secondary gene pool (GP2): The secondary gene pool includes all those species that hybridize with those of the primary gene pool with some to considerable difficulty, and the hybrid is at least partially fertile, The difficulty in hybridization is due to ploidy differences, chromosome alternations, or genetic barriers. Members of this group are often used in breeding programs. There is some reproductive barrier between members of the secondary gene pool and primary gene pool, which leads to partial sterile and weak hybrid, chromosomes may pair poorly or not at all, difficulty in recover of desire phenotype in subsequent generations, and efforts are required for available gene pool utilized by plant breeder or geneticist.

20. 3. Tertiary gene pool (GP3): Members of tertiary gene pools cross with the members of the primary gene pool with consideration to great difficulty, and hybrids, if produced, are anomalous, lethal, or completely sterile. To exploit germplasm from distant relatives, tools such as embryo rescue and bridge crossing may be used to nurture an embryo from a wide cross to a full plant and to obtain fertile plants. Used only occasionally in breeding programs. Gene transfer from GP3 to GP2 is relatively easier. The primary and tertiary gene pools can be intermated , but without any special technique (such as embryo rescue, induced polyploidy, and, bridging crosses), gene transfer between them is impossible.  Some crop plants have no secondary gene pools. Some examples are barley, soybean, onion, and broad bean.

21. Evaluation Evaluation refers to screening of germplasm in respect of morphological, genetical , economic, biochemical, physiological, pathological and entomological attributes . Evaluation requires a team of specialists from the disciplines of plant breeding, physiology, biochemistry , pathology and entomology. First of all a list of descriptors (characters) for which evaluation has to be done is prepared. This task is completed by a team of experts from IPGRI , Rome , Italy. The descriptors are ready for various crops. The evaluation of germplasm is done in three different places, viz ., ( 1)in the field ,( 2)in greenhouse, and (3) in the laboratory. Cataloguing, Data storage and Documentation It refers to compilation , analysis , classification storage and dissemination of information . In plant genetic resources, documentation means dissemination of information about various activities such as collection , evaluation, conservation, storage and retrieval of data. Now the term documentation is more appropriately known as information system. Documentation is one of the important activities of genetic resources ..

22. Distribution The specific germplasm lines are supplied to the users on demand for utilization in the crop improvement programmes . Distribution of germplasm is theresponsibility of the gene bank centres The germplasm is usually supplied to the workers who are engaged in research work of a particular crop species . Supplied free of cost to avoid cumbersome work of book keeping . The quantity of seed samples depends on the availability of seed material and demands Proper records are maintained about the distribution of material . It helps in acclimatization and purification of the material .   Utilization It refers to use of germplasm in crop improvement programmes . The germplasm can be utilized invarious ways.The uses of cultivated and wild species of germplasm are briefly discussed below :

23. CultivatedGermplasm It can be used in three main ways :( 1)as a variety ,(2 ) as a parent in the hybridization, and(3) as a variant in the genepool . Wild Germplasm It is used to transfer resistance to biotic and abiotic stresses, wider adaptability and sometimes quality such as fibre strength in cotton . Organizations associated with germplasm IPGRI– InternationalPlantGeneticResourcesInstitute NBPGR– NationalBureauofPlantGeneticResources