In F2, the favourable combination of dominant and recessive genes is broken due to segregation and recombination. 2. Selected superior plants in III year are space planted to study the individual plant. It is used when the desirable character is not found within the species of a crop. Therefore, crop improvement through biotechnological approaches, appears to be time effective and alternative approach. Gossypium, hirsutum, G. barbadense, G. arboreum and G. herbaceum. 4. All the hybrid seeds of maize to farmers for cultivation are nothing but double crosses. (f) Male Sterility or Self-incompatibility Method: Emasculation option can be eliminated by the use of male-sterile plants, In some self-pollinated plants for example, Sorghum, Onion, Barley etc. International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico. In this method all desirable characters of a popular variety (genotype known) are retained except the undesirable genes at a particular locus is replaced. Karpechenko (1928): An intresting intergeneric hybrid, Raphanobrassica, was produced. 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. Plays a pivotal role in the improvement of the crop species specially the vegetatively propagated ones. Crosses between tetraploid species G. hirsutum and G. barbadense and between diploid species G. arboreum and G. herbaceum are fully fertile. It is an effective means of transferring desirable genes into cultivated plants from related species and genera. In such hybrids, recombination between chromosome segments during meiosis may lead to production of gametes with deletions or duplications. This may result due to three main factors: (i) Unfavourable interaction between chromosomes of two species. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. 5. 3. Seed certification, seed testing and storage. Similarly, most of the modern cultivars of potato are derivatives of interspecific hybrids. It is commonly known as ‘Fairchild Mule’. (vii) Harvesting and Storing the F1 Seeds: Crossed heads or pods of desirable plants are harvested and after complete drying they are threshed. The emasculated flower or inflorescence is immediately bagged to avoid pollination by any foreign pollen. The intervarietal crosses may be simple or complex depending upon the number of parents involved. Distant hybridization occurs under both natural and artificial conditions. The natural or artificial process that results in the formation of hybrid is known as hybridization. 5. The cross between American cultivated cotton (G. hirsutum, 2n = 52) and American wild diploid (G. thurberi) are partially fertile, because these two species have chromosomes of D genome in common. All these meiotic irregularities lead to structural chromosomal changes, viz. Distant hybridization and role of biotechnology in crop improvement: 1. Such crosses are rarely used in crop improvement because of various problems associated with them. The interspecific crosses vary from complete fertility to complete sterility. Distant hybridization, especially with Jatropha species though might have potential in genetic improvement (Sujatha and Prabakaran, 2003), has so far remained unexploited, due to incompatibility in the castor–Jatropha combinations probably due to poor pollen germination and abnormal pollen tube development or incompatible interaction of pollen with stigma and style (Reddy … Intergeneric hybrids have great potential for the improvement of germplasm. 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. In sugarcane, cold tolerance has been transferred from wild species in USA. Find paragraphs, long and short essays on ‘Distant Hybridization’ especially written for school and college students. There is occasional seed set in this cross. Now hybrid derivatives of Tripsacum x diploid maize are being utilized in commercial crop improvement programmes. It presents biotechnology as providing powerful and useful tools, in a continuum of technical evolution that contributes or could contribute to the improvement of crop production, food quality and safety, while preserving the environment. Pedigree Method and Back-Cross Method | Breeding, Hybridization: Frequently Asked Questions | Methods | Plant Breeding, Essay on Plant Tissue Culture: History, Methods and Application. 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). A cross-involving more than one inbred line is referred to as multiple cross. Sometimes, the sterility is due to small structural changes in chromosomes which is not detectable during meiosis. This method is used particularly for transferring a single simply inherited character like disease, frost or drought resistance and earliness from an undesirable variety to a good commercial variety. the improvement of few crop species is primarily based on interspecific hybridization example like Sugarcane. Resistance to boll weevil and jassids in cotton and leaf chewing insects in peanut has been incorporated from wild species. Another example is garden strawberry which has evolved from a natural interspecific cross between American octaploids Fragaria cliloensis and F. virgineana in a botanical garden. (i) This method takes much longer time to develop a new variety. production of disease-free clones, inducing somaclonal variations, developing hybrids, gene pool conservation, incorporating desired traits by distant hybridization… Less progress has been made on insect resistance. This method has limited utility except in high risk areas where severe disease damage occurs regularly from a highly specialized disease pathogen. In some cases, pollen tube is short and style is very long, due to species difference. Mol Biol Plants 15(1):3–22 When the F1 plants were treated with colchicine, a fully fertile tetraploid (2n = 48) was obtained which resembled cultivated species (N. tabacum). For instance, anther/microspore culture, somaclonal variation, embryo culture and somatic hybridization are being exploited for obtaining incremental improvement in the existing cultivars. This combines yield potential and grain quality of wheat and hardiness of rye. Hybridization does not change genetic contents of organisms but it produces new combination of genes. There are two examples of new crops which have evolved through distant hybridization. The field of biotechnology and molecular biology revolutionize the agriculture and farming methods. Several modern cultivars of sugarcane have been developed from crosses of Saccharum officinarum with S. spontaneum or S. barberi. Intergeneric cross between radish (Raphanus sativus) and caage (Bassica oleracea) of the family Cruciferae was made by Karpechenko in 1928 in Russia. Semi-dwarf wheat has obtained from Triticum x Agropyron hybrid derivatives. The fertility has to be restored by doubling of chromosomes through colchicine treatment. Intereneric hybridization has been generally used in asexually propagated species. Crop improvement: Biotechnology is widely used to produce high yielding varieties of crops. (ii) Selfing of parents or artificial self-pollination. : Sometimes, homozygous dominant alleles on several loci prefer to remain in one species and homozygous recessive alleles at the same loci in another species. FA plants are grown and their F5 seeds are harvested in bulk. G. arboreum (2n = 26) x G. herbaceum (2n = 26) → F1 plants are fully fertile. It is the only method used for the interspecific transfer of characters, transfer of qualitative characters, quantitative characters, transfer of cytoplasm, particularly for male sterility and for the production of isogenics lines. For example, wild species have been used to transfer dark green colour and excellent leaf texture in lettuce and bright red thin flesh in red peppers. Techniques like alien addition and alien substitution may also be effective. Wild Sorghums—Their Potential Use in Crop Improvement 57 resources including direct hybridization, reproductive barriers and their circumvention, chromosome and physiological manipulation, the gaps between hybridization and utilization and molecular interventions. It is first crossed with N. repanda and the resulting amphidiploid is crossed with N. tabacum. It may enhance the chances of obtaining a zygote. The success of seed set is generally very low in wide crosses. Select the BC1 plants possessing desired characters of A with disease resistance of B. These types may not be necessarily the best yielding types. Use of wild species in the hybridization programmes sometimes leads to alteration in the mode of reproduction. Inbreeds are grown under normal conditions and are emasculated. Here is an essay on ‘Distant Hybridization’ for class 8, 9, 10, 11 and 12. 6. 3. Interspecific hybridization is more successful in vegetatively propagated species like sugarcane and potato than in seed propagated species. Disclaimer Copyright, Share Your Knowledge 3. After inserting the panicle inside the container a cork is fitted in the hole to close it. Types of Distant Hybridization: Distant hybridization is of two types, viz: Crossing or mating between two different species of the same genus is referred to as interspecific hybridization. There are eight genera in which intergeneric hybrids have been made with sugarcane (Saccharum). The first is the Triticale which has evolved from intergeneric cross between Triticum aestivum and Secale cereale. Trials of superior lines are confirmed. It is an effective means of transferring desirable genes into cultivated plants from related species and genera. deletions, duplications, translocations and inversions which cause absence of pollen formation or formation of nonfunctional or abortive pollens. G. hirsutum (2n = 52) x G. barbadense (In = 52) → F1 plants are fully fertile. has been transferred from wild species of these crops in Russia. In this method the amount of pressure is applied in such a way that only anthers are sucked out and other parts of the flower like gynoecium remain intact. It is one of the major drawback of this method. The male sterility is the most common alteration in the mode of reproduction which results from interspecific hybridization. The other wild species are perennials. Distant hybridization has played significant role in: (2) Developing commercial hybrids in some crops, and. The F1 hybrids were sterile in all the three crosses. 2. 4. Distant hybridization 1. in 1980. Wide crossing is an effective method of exploiting desirable characters from wild species for the improvement of cultivated crop plants. Triticum aestivum (2n = 42) x T. compactum (2n = 42) → F1 plants are fully fertile. Molecular markers. The methods of crop variety improvement are hybridisation, genetic engineering etc. Plants are chosen for hybridization and F1 seeds are produced. Thus pollen tube cannot reach ovule to effect fertilization. 2.5 Somatic hybridization. Intergeneric hybridization is used when the desirable genes are not found in different species of the same genus. Commercial hybrids are produced by this method. During the testing period observations are made on height, tendency to lodge, maturity, disease resistance and quality. Because reciprocal crosses are successful in some cases. New variety is tested in replicated field trials along with the variety A as check. The new plants can be regenerated from the embryoids in the culture medium. These crosses combine high sugar content of S. officinarum with the disease resistance, cold tolerance and vigour of S. spontaneum and S. barberi. Breeder does not require to handle large populations. The F1 was sterile which was made fertile through colchicine treatment. Seeds are multiplied and released for cultivation. A hybrid between Pearl-millet and napier grass has been developed which has become very popular by virtue of its high fodder yield potential and superior fodder quality. Most of the modem cultivars of sugarcane and potato are the derivatives of interspecific hybridization. The F1 was sterile. There are several methods of improvement of self-fertilized crops by hybridization. Essay # 3. The F1 was sterile. The problem of hybrid sterility is more acute in intergeneric crosses than in interspecific crosses. After chromosome doubling, each chromosome will have a pairing partner at meiosis. In another words, failure of male and female gametes to unite to form zygote in interspecific and intergeneric hybrids is known as cross incompatibility. The embryo cultures have been identified and developed for various plant species. This leads to non-pairing or reduced pairing of chromosomes resulting in following meiotic abnormalities: i. Scattering of chromosomes throughout spindles during metaphase I. ii. Essay # 4. Chemical method is commonly used technique using polyethylene glycol . What are the characters Mendel selected for his experiments on pea plant? The total number of possible different single crosses produced by a given number of inbreeds can be calculated by the formula n(n-1)/2 where n is the number of inbreeds. The methods of crop variety improvement are hybridisation, genetic engineering etc. New crop species have been developed by overcoming the F 1 sterility and producing amphidiploids and such crops are commercially being grown in the field. For example, protein content in rice, oats and rye; fibre length in cotton; oil quality in oil palm; carotenoid content in tomato; starch content in potato; leaf quality in tobacco; and oil per cent in oats have been improved through the use of their wild species in the hybridization programme (Table 28.3). 12, 13. The important tetraploid hybrids include Varalaxmi, JKHY 11, CBS 156, Savitri, DCH 32, HB 224, NHB 12, TCHB 213 DHB 105 and Sruthi. The F1 was sterile. 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. Agriculture biotechnology is defined as that is used for livestock and crop improvement. Hybrid breakdown hinders the progress of interspecific gene transfer. In this method, several pure lines are crossed together. Normally 20-50 families may be retained at the end of F5 generation. Interspecific hybridization leads to introgression which refers to transfer of some genes from one species into the genome of another species. 1. 2. History Thomas Fairchild (1717): The first authentic record of a distant hybridization for crop improvement is the production of a hybrid between Carnation (Dianthus caryophyllus) and Sweet willian (Dianthus barbatus). The bags may be made of paper, butter paper, glassine or fine cloth. Mendel onward, the hybridization had become the key method of crop improvement. lack of pollen germination, insufficient growth of pollen tube to reach ovule and inability of male gamete to unite with egg cell. 4. Multi-locations field trials are carried out, best performing strain is multiplied for seed distribution. This problem has been overcome in certain interspecific crosses by using the mixture of pollen from compatible (self) and incompatible parents. Such crosses are called distant crosses. white oat (Avena sativa) and red oat (Avena byzantiana). Before sharing your knowledge on this site, please read the following pages: 1. These aspects are briefly discussed below: Distant hybridization has been instrumental in transferring disease resistance from wild species into cultivated ones. DDH 2 in Karnataka and Pha 46 in Maharashtra. Molecular markers have been used for evaluation of genetic variability in castor. Main features of interspecific hybridization are given below: 1. Intergeneric hybridization refers to crossing between two different genera of the same family. Crosses are successful in both directions, but hybrids can be more easily produced when Tripsacum is used as the female parent, because the maize pollens are able to produce long pollen tube to reach the ovule. 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. The chromosome behaviors in F1 hybrids provide us with the essential genetic basis for chromosome manipulation. Butter paper or vegetable parchment bags are most commonly used. This is the cross of a number (4-10) pretested hybrids and is done by open pollination in isolation. 3. Hybridisation (biology), the process of combining different varieties of organisms to create a hybrid. Sometimes, distant hybrids have several undesirable characters such as non-flowering, late maturity and seed dormancy and useless combinations like Raphanobrassica. The progeny of each single plant is grown separately and superior progeny are selected and isolated (F8). Hybridization was first of all practically utilized in crop improvement by German botanist Joseph Koerauter in 1760. This method was first proposed by Harlan and Pope (1922). But N. sylvestris can cross with N. tabacum. There are two main causes of hybrid breakdown, viz. Flowers or inflorescences are immersed in alcohol of a suitable concentration for a brief period. Extensive yield tests are not required because the performance of the recurrent parent is already known. Cross incompatibility results due to unfavourable interaction between the protein of pistil and pollen which inhibits normal germination and growth of pollen tube. In the field water is carried in a thermos jug (Fig. The following techniques may be useful to overcome the problem of hybrid inviability: Proper choice of parents, making reciprocal crosses and application of growth hormones increase favourable conditions for the development of zygote into viable seed. This method is rarely used in crop improvement programmes and that too for transfer of some specific characters into cultivated species from allied genera. Further breeding in these hybrids is carried out according to either pedigree or bulk method. Preliminary yield test are conducted (F9). The F1 cross between such species would be heterozygous and vigorous. ... 2017, Crop improvement: new approache s and . biotechnology is the term used in crop and livestock improvement through biotechnology tools. DNA finger printing and seed registration. It is a mechanical method and is suitable for the crops having minute flowers. Again the F1 was sterile. This is used when hybrid zygote is unable to develop. Both these species are annual diploid (2n = 40). Treatment of F1 with colchicine resulted in the production of fertile amphidiploid (2n = 48) which was similar to cultivated species N. rustica. The cleistogamy and self-fertility traits of wild Secale have been transferred to cultivated rye (secale cereale). Hybridization was first of all practically utilized in crop improvement by German botanist Joseph Koerauter in 1760. It requires lot of time and money. 5. The bagging is done with the emasculation in bisexual plants and before the stigma receptivity and dehiscence of the anthers in unisexual plants. In cotton, there are two types of species, viz. Some of the following biotechnology tools which play vital role in agriculture biotechnology are- In such situation either reciprocal cross should be made or the style should be cut to normal size before pollination. Thus embryo culture technique is an effective way of overcoming the problem of hybrid zygote development. For example, interspecific cross between Vigna radiata and V. mungo is successful only when former is used as female and later as male parent. In India, interspecific hybrids have been developed for commercial cultivation in cotton. Finally, the F1 plants of double crosses are crossed with each other to produce hybrids [(A × B) x (C x D)] x [(E x F) x (G x H)]. Some of the varieties of upland cotton (MCU 2, MCU 5, Deviraj, Devitej, G 67, Khandwa 1, Khandwa 2, Badnawar 1 PKV081, Rajat and Arogya) are derivatives of interspecific hybridization. It is a cross of a single cross (used as female) with another inbred (used as male), i.e., it involves three inbreeds [(A x B) x C], The single cross and the inbreeds are planted in the same way as the inbreeds in the single cross. This may be used when other techniques do not work in interspecific or intergeneric gene transfer. iii. Cytoplasmic male sterility has been transferred from wild species to cultivated ones in wheat, barley, cotton, tobacco, ryegrass and several other crops. Non-radioactive DNA technology … F1 hybrids between two genera are always sterile. The resulting hybrid combines desirable character of both the parents. Hybridization Methods of Plant Breeding in Cross-Pollinated Crops. When F1 plants of an interspecific cross are vigorous and fertile but their F2 progeny is week and sterile, it is known as hybrid breakdown. Suppose there are two varieties A and B. The crosses between G. max and G. Soja are fully fertile. The plants which do not have a dominant allele at each locus or which are not homozygous for all recessive alleles would be weak and sterile. Several intergeneric crosses have been made in sugarcane. 14). The selected pure lines are first combined into crosses as A × B, C × D, E × F, G × H and so on. There are three main reasons of cross incompatibility, viz. Wide crossing or distant hybridization has been used in the genetic improvement of some crop plants. These hybrids give very high yield in small land without any increase in the cost of production. Grafting of interspecific hybrid on to the cultivated species helps in making the cross successful. However, in this method 10-15% self pollination takes place. (The process may be repeated until the desired period of homozygosity is achieved. Wide hybridization A critical requirement for crop improvement is the introduction of new genetic material into the cultivated lines of interest, whether via single genes, through genetic engineering, or multiple genes, through conventional hybridization or tissue-culture techniques. Hybrid breakdown is a major problem in interspecific crosses. Role of environment is almost negligible. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Now Triticale is commercially grown in countries like Canada and Argentina. Distant crosses are more successful in more closely related species or genera than in less closely related species or genera. Treatment of F1 plants with colchicine resulted in the production of fertile amphidiploid (2n = 52) which was similar to upland cotton (G. hirsutum). Triticale is the best example of the practical achievements of intergeneric hybridization. These hybrids are grown in south and central cotton growing zones. To artificially create a variable population for the selection of types with desired combination of characters. This is a major problem in distant hybridization. Seeds are multiplied and distributed to the farmers. 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. Stigma should be receptive and anthers should not have dehisced. Several special techniques, viz. Types of Hybridization Based on the taxonomic relationship of the two parents, hybridization may be classified into two broad groups. Interspecific crosses are fully fertile between those species that have complete chromosomal homology. Stebbins termed it as criptic structural hybridity. In crop improvement programme this type of hybridization is commonly used E. g crossing of two varieties of wheat or other crops. 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. Interspecific crosses are partially fertile between those species which differ in chromosome number but have some chromosomes in common. The need for producing so many varieties of different crop plants is to attract more consumers. Wide or distant hybridization has been widely used as an important tool of chromosome manipulation for crop improvement. In some cases, sterility has been found to be associated with completely normal pairing of chromosomes (genie sterility). After any one of the above-mentioned crosses, seeds are tested, multiplied and distributed. diploid (2n = 14), tetraploid (2n = 28) and hexaploid (2n = 42). vi. In some crops (e.g., Jowar, Bajra) the inflorescences of both the parents are enclosed in the same bag. It is summarized in Figs. (vii) Harvesting and storing the F, seeds. Following are the important precautions while performing this method: i. The treatment of F1 plants with colchicine resulted in the production of fertile amphidiploid in each cross as given below: Interspecific crosses were made between green-gram (Vigna radiata, 2n = 22) and black-gram (V. mungo, 2n = 22) by Singh and Singh, 1975 and others. Applications of Distant Hybridization: The application of distant hybridization in crop improvement is not an easy task. This method differs from the pedigree method in that no selection is practiced in F2-F5 generations (Fig. In some crops, wild species have been used to improve the quality of cultivated ones. Related species and genera achieved from use of desirable genes are not in! 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