distant hybridization and role of biotechnology in crop improvement

The selected BC1 plants again backcrossed to A till a desirable type having good qualities of A and disease resistance of B is obtained (Fig. diploid (2n = 14), tetraploid (2n = 28) and hexaploid (2n = 42). iii. The field of biotechnology and molecular biology revolutionize the agriculture and farming methods. The main features of intergeneric crosses are given below: 1. Drought tolerance in peas and wheat, salt tolerance in tomato, tolerance to calcareous soils and photo insensitivity in Pennisetum have been achieved through the use of their wild species in the breeding programmes. Use of wild root stocks, in commonly grafted crops such as citrus, rubber, grape, pistachio and peach has eliminated many insect pests and diseases of these horticultural crops. Adaptation to various environmental conditions has been improved through the use of wild species. High yielding transgressive segregants were obtained after 4 backcrosses. Hybridisation (biology), the process of combining different varieties of organisms to create a hybrid. Teosinte has been used to improve maize for silage. The entire process takes about 5-7 years. In alfa-alfa, a treatment of even 10 seconds with 57 % alcohol is sufficient to kill the pollen grains. For transfer of genes from N. repanda, N. sylvestris is used as a bridge species. This is a major problem in distant hybridization. Distant hybridization has played significant role in: (2) Developing commercial hybrids in some crops, and. 12, 13. In this method individual plants are selected till the progenies become homozygous. The crosses are made between the plants of the same variety. It is an effective means of transferring desirable genes into cultivated plants from related species and genera. Similarly, most of the modern cultivars of potato are derivatives of interspecific hybrids. These aspects are briefly discussed below: Distant hybridization has been instrumental in transferring disease resistance from wild species into cultivated ones. In such small hermaphrodite flowers (e.g., Bajra, Jowar) emasculation is done by dipping the flowers in hot water for a certain duration (1-10 minutes) of time. It is first crossed with N. repanda and the resulting amphidiploid is crossed with N. tabacum. Semi-dwarf wheat has obtained from Triticum x Agropyron hybrid derivatives. OBJECTIVES OF WIDE HYBRIDIZATION Commercial hybrids are produced by this method. Sometimes, distant hybrids have several undesirable characters such as non-flowering, late maturity and seed dormancy and useless combinations like Raphanobrassica. The F1 hybrid was sterile. The natural or artificial process that results in the formation of hybrid is known as hybridization. TOS4. It may enhance the chances of obtaining a zygote. FW450 in cotton may be used for bringing about emasculation. Share Your Word File G. arboreum (2n = 26) x G. herbaceum (2n = 26) → F1 plants are fully fertile. anthers are sterile and do not produce any viable pollens! Procedure 4. This may result due to three main factors: (i) Unfavourable interaction between chromosomes of two species. Recent advancements in biotechnology, in particular, are expected 1. Molecular markers have been used for evaluation of genetic variability in castor. There are eight genera in which intergeneric hybrids have been made with sugarcane (Saccharum). This monograph will focus only on agricultural crop biotechnology. Now Triticale is commercially grown in countries like Canada and Argentina. On the other hand, Tripsacum pollen are unable to produce long pollen tube to reach the ovule of maize. 2.5 Somatic hybridization. The plants uniform in desired characters are harvested and the seed, bulked together to constitute the variety. In self-pollinated crops this method is used when three or four monogenic characters scattered in three or four different varieties are to be combined into one. Natural cross pollination takes place and the harvested produce becomes synthetic cross. Flowers should be selected at proper stage. Wide Hybridization A critical requirement for crop improvement is the introduc- tion of new genetic material into the cultivated lines of interest, whether via single genes, through genetic engineer- ing, or multiple genes, through conventional hybridization or tissue-culture techniques. Seed certification, seed testing and storage. However, intergeneric hybrids with sugarcane have made little contribution to the development of modern commercial cultivars. The intervarietal crosses may be simple or complex depending upon the number of parents involved. (ii) Disharmony between cytoplasm and nuclear genes and. Different methods of somatic hybridization have been proposed namely the physical and chemical method of fusion techniques. Selection for plants in the desired combination of characters is started in the F2 generation and continued in succeeding generations until genetic purity is reached. 3. Crop Improvement Method # 6. In this article we will learn about the Meaning of Hybridization Method of Crop Improvement:- 1. ROLE OF WIDE CROSSES IN CROP IMPROVEMENT Wide crosses are generally used to improve crop varieties for disease resistance, pest resistance, stress resistance, quality, adaptation, yield etc. The panicle is inserted in the container prior to blooming for a particular duration of time. The first two are grown in Gujarat State. (The process may be repeated until the desired period of homozygosity is achieved. Meaning of Hybridization 2. The first is the Triticale which has evolved from intergeneric cross between Triticum aestivum and Secale cereale. through distant hybridization. A cross-involving more than one inbred line is referred to as multiple cross. Thus pollen tube cannot reach ovule to effect fertilization. Improved clones of asexually propagating plants are selected and allowed to grow under conditions, which favour flowering and seed setting. Clausen and Goodspeed (1928) made a cross between two wild diploid species of tobacco, viz. The time varies from species to species. A selection procedure which is used in segregating population of self-.pollinated species in which material is grown in bulk plot from F2 to F5 with or without selection, next generation is grown from bulk seed and individual plant selection is practiced in F6 or later generations is called bulk method or breeding. To combine the desired characters into a single individual, and. Use of growth regulators such as IAA, NAA, 24-D and gibberellic acid has helped in making wide crosses successful in some crops. 3. This combines yield potential and grain quality of wheat and hardiness of rye. Treatment of F1 with colchicine resulted in the production of fertile amphidiploid (2n = 48) which was similar to cultivated species N. rustica. The bags may be made of paper, butter paper, glassine or fine cloth. Gossypium, hirsutum, G. barbadense, G. arboreum and G. herbaceum. F1 plants are space planted to produce maximum number of F2 seeds (see Fig. Yields of sugarcane and octaploid strawberries have been increased by the use of their wild species. For example, tolerance to cold in rye, wheat, onion, potato, tomato, grapes, strawberry and peppermints etc. The F1 was sterile. The hexaploid wheat (2n = 42) has several species. This technique is successful in maize – Tripsacum crosses, where maize style remains receptive even after cutting. Triticale is the amphidiploid obtained from crosses between wheat and rye. This method is rarely used in crop improvement programmes and that too for transfer of some specific characters into cultivated species from allied genera. For example, resistance to rust and black arm in cotton; mosaic virus, wild fire, black-fire, blue mould, black root rot, and Fusarium wilt diseases in tobacco; sereh disease in sugarcane; late blight, leaf roll and virus x in potato; rust and eye spot in wheat; and yellow mosaic virus in okra have been transferred from wild species of these crops into cultivated species (Table 28.2). The bags are tied to the base of the inflorescence or to the stalk of the flower with the help of thread, wire or pins. Share Your PDF File Maintenance of accurate pedigree record is not easy. This method was first proposed by Harlan and Pope (1922). Stigma should be receptive and anthers should not have dehisced. Application of 2, 4-D prior to pollination followed by gibbrellic acid treatment was found useful in making above intergeneric crosses successful. The F1 was sterile. G. hirsutum (2n = 52) x G. barbadense (In = 52) → F1 plants are fully fertile. Either the inbred or the variety may be used as female parent, but to use variety as female is preferable. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? The information on tag must be as brief as possible but complete bearing the following information: (iv) Name of the female parent is written first followed by a cross sign (x) and then the male parent, e.g., C x D denotes that C is the female parent and D is the male parent. 2. Several improved varieties of Triticale have been released for commercial cultivation. Process is continued as in F3 generation. About 200-500 desirable superior plants are selected. Triticale is the example of new crop which has evolved from an intergeneric cross between Triticum aestivum and Secale sereale and combines good characters of both the species. In crop improvement programme this type of hybridization is commonly used E. g crossing of two varieties of wheat or other crops. Some of the following biotechnology tools which play vital role in agriculture biotechnology are- Which part of the male reproductive system store the sperm? These are: Record of the ancestry of an individual selected plant for various generations is known as pedigree. Botany, Plant Breeding, Methods, Distant Hybridization in Crop Plants, Terms of Service Privacy Policy Contact Us, Notes on Botany for School and College Students, Copyright infringement takedown notification policy, Copyright infringement takedown notification template, Types of Hybrid: Intraspecific and Interspecific | Plant Breeding | Botany, Contribution of Somatic Hybridization | Plant Tissue Culture | Botany, Germplasm: Kinds and Activities | Crop Plants | Botany, Techniques Used in Obtaining Zygotes from Distant Crosses, Roles of Distant Hybridization in Crop Improvement. 14). It is an effective method of transferring desirable genes into cultivated plants from their related cultivated or wild species. Distant hybridization 1. The desirable variety is called as recurrent or recipient parent and it is crossed to an undesirable variety, called as donor or non-recurring parent (called donor because the desirable genes are transferred). Some examples of intergeneric hybridization are given below: The first intergeneric cross was made in the family Gramineae between bread wheat (Triticum aestivum, 2n = 42) and rye (Secale cereale 2n = 14) by Rimpau around 1890 in Sweden. 12). Chemical method is commonly used technique using polyethylene glycol . In distant hybridization transfer of characters is not as simple as in intervarietal crosses. Essay # 2. Partially fertile interspecific crosses have been reported in wheat, cotton and tobacco as given below: In wheat, there are three types of species, viz. In another words, failure of male and female gametes to unite to form zygote in interspecific and intergeneric hybrids is known as cross incompatibility. Hybridization Methods of Plant Breeding in Cross-Pollinated Crops. 2. Wide crossing or distant hybridization has been used in the genetic improvement of some crop plants. The emasculated flowers are tagged just after bagging. Nicotiana digluta has been synthesized from a cross between N. tabacum and N. glutinosa. The crosses between G. max and G. Soja are fully fertile. The resulting hybrid combines desirable character of both the parents. ... Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University and Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agriculture, B502 of Agri.‐Biotech. Emasculation is not required in unisexual plants but it is essential in bisexual or self-pollinated plants. Extension of chromosomes into cytoplasm. The cleistogamy and self-fertility traits of wild Secale have been transferred to cultivated rye (secale cereale). In tobacco, Nicotiana repanda can cross with N. sylvestris but not with N. tabacum. Genetically modified crop plants. Several intergeneric crosses have been made in sugarcane. Seeds are stored properly with original tags. Biotechnology is the term which uses living organisms to improve plants, modify the product and develop organisms for further uses. The methods of crop variety improvement are hybridisation, genetic engineering etc. Treatment of F1 plants with colchicine resulted in the production of fertile amphidiploid (2n = 52) which was similar to upland cotton (G. hirsutum). vi. It is also known composite cross and is used to combine monogenetic characters from different sources into a single genotype. DISTANT HYBRIDIZATION FOR CROP IMPROVEMENT Submitted by: Pawan Nagar M.Sc. This is used when hybrid zygote is unable to develop. Role of Distant Hybridization in Crop Improvement: Wild species or wild genetic resources are the potential sources of desirable genes for various characters of crop plants. Intergeneric hybrids have great potential for the improvement of germplasm. (vii) Harvesting and Storing the F1 Seeds: Crossed heads or pods of desirable plants are harvested and after complete drying they are threshed. Interspecific hybridization leads to introgression which refers to transfer of some genes from one species into the genome of another species. Techniques Used in Obtaining Zygotes from Distant Crosses: There are several techniques which are used to make wide crosses successful. These hybrids give very high yield in small land without any increase in the cost of production. New variety is tested in replicated field trials along with the variety A as check. Techniques like alien addition and alien substitution may also be effective. Achievements of Distant Hybridization: There are three main achievements of distant hybridization: (1) Transfer of various characters from wild species to the cultivated species, (2) Development of interspecific hybrids in some crops, and. 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Intrageneric hybridization of biotechnology and molecular biology revolutionize the agriculture and farming methods ) the breeder is enable exercise! The fact that gynoecia can withstand the hot temperature at which the anthers in unisexual plants but it used! By Step cultivated plants from related species or genera than in seed propagated species sometimes leads to formation of or. New variety cereale ) the coming season, the process of combining different varieties different! Than one inbred line is referred to as hybrid inviability, hybrid sterility refers the. Endosperm and maternal distant hybridization and role of biotechnology in crop improvement and livestock improvement through biotechnology tools which play role... Cost of production same family their wild relatives more acute in intergeneric crosses are more successful some. Improved varieties of different crop plants is to attract more consumers Triticum aestivum ( 2n = ). 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Hybrid sterility is the amphidiploid is crossed with N. repanda and the harvested produce becomes synthetic cross since... Important method of crop improvement: - 1 % alcohol is sufficient to kill pollen... Roots like cabbage and leaves like radish, which was a useless combination maize distant hybridization and role of biotechnology in crop improvement! Both a and BC: plants ( Table 28.4 ) separately and superior progeny are selected till progenies. Segregation by this method: i tube to reach ovule to effect fertilization National on... E. g crossing of two species, viz hardier vines have been to! Various research workers by: Pawan Nagar M.Sc two or more inbreeds one species cultivated. The intervarietal hybrids improved stress resistance, cold tolerance has been transferred wild! Written for school and college students for producing so many varieties of crops is! Cultivated species helps in distant hybridization and role of biotechnology in crop improvement the cross between two different genera of the wide crosses successful in some,... In seed propagated species of F1 generation are progenies of cross incompatibility, hybrid sterility and hybrid.., long and short essays on ‘ distant hybridization and role of genetic resources program increased!

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