In some cases, pollen tube is short and style is very long, due to species difference. Somatic hybridization Somatic hybridization allows fusion of complete cytoplasm of two parents. e.g., from four inbreeds six single crosses can be produced. This combines yield potential and grain quality of wheat and hardiness of rye. Now Triticale is commercially grown in countries like Canada and Argentina. This method is not commonly used for emasculation because duration of treatment is an important factor since a very short duration is required failing which even the gynoecium may be damaged. Inbreeds are grown under normal conditions and are emasculated. 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 … Quality has also been improved in several crop plants. Emasculation is the removal of stamens from female parent before they burst and shed their pollens. 6). This method is less effective than hot water treatment. The cross between common wheat (Triticum aestivum, 2n = 42) and durum wheat (T. durum, 2n = 28) are partially fertile. Wide crossing is an effective method of exploiting desirable characters from wild species for the improvement of cultivated crop plants. 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. Intergeneric hybridization was used by some workers to develop new crop species. 2. A is very good in all characters but disease susceptible and the variety B is disease resistant but very poor in all characters. The entire process takes about 5-7 years. In F1 there are 14 bivalents and 7 univalents during meiosis. It is the sixth step. Lagging of chromosomes during anaphase. 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. These genera include Eccoilopus, Erianthus, Miscanthidium, Miscanthus, Narenga, Rapidum, Sclerostachya and Sorghum (sweet sorghums). These barriers are known as pre-fertilization barriers. Intergeneric hybridization is used when the desirable genes are not found in different species of the same genus. 50-100 F1 plants are grown and their F2 seeds are harvested in bulk. 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. Hybridization Methods of Plant Breeding in Cross-Pollinated Crops. (iii) Unfavourable interaction among embryo, endosperm and maternal tissues. Semi-dwarf wheat has obtained from Triticum x Agropyron hybrid derivatives. (ii) Hybridization has to be done for each backcross. 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. Pedigree Method and Back-Cross Method | Breeding, Hybridization: Frequently Asked Questions | Methods | Plant Breeding, Essay on Plant Tissue Culture: History, Methods and Application. This inability of a hybrid zygote to grow into a normal embryo under the usual conditions of development is referred to as hybrid inviability. Seeds are multiplied and released for cultivation. Wide hybridization involves hybridization between cultivated species and their wild relatives. Chromosomes in such hybrids have normal pairing at meiosis and as a result the F1 plants are fully fertile. Plant tissue culture also one of the applications of biotechnology used to improve crops and used to increase the speed or efficiency of the breeding process, to improve the accessibility of existing germplasm and to create new variation for crop improvement. has been transferred from wild species of these crops in Russia. To measure the temperature, in the upper side of the container a thermometer is placed. (Synonyms, poly-cross and strain building). It is a modified form of pedigree method in which segregating material is handled by bulk (mass) method when conditions are unfavorable for selection and by pedigree method when conditions are favourable for selection. It is used when the desirable character is not found within the species of a crop. It is used not only for the developing hybrid but to test the combining ability of the inbreeds. TOS4. The crosses between G. max and G. Soja are fully fertile. Selected plants of A and B are crossed to raise the F1 Here A is treated as the female and B as male. Distant crosses are more successful in more closely related species or genera than in less closely related species or genera. The cleistogamy and self-fertility traits of wild Secale have been transferred to cultivated rye (secale cereale). Many of the intergeneric hybrids are easily made with the help of male sterility. 2. Answer Now and help others. Meiosis in F1 leads to formation of 13 bivalents and 13 univalents. Various characters such as disease and insect resistance, improved quality and adaptation, earliness, dwarfness, tolerance to frost, drought and salinity have been transferred from wild species to the cultivated species through interspecific and intergeneric hybridization. Following are the important precautions while performing this method: i. The F1 cross between such species would be heterozygous and vigorous. ... 2017, Crop improvement: new approache s and . G. arboreum and G. herbacium. The interspecific crosses vary from complete fertility to complete sterility. The fertility has to be restored by doubling of chromosomes through colchicine treatment. Again the F1 was sterile. Both these species are annual diploid (2n = 40). It is the third step in hybridization. In such hybrids, recombination between chromosome segments during meiosis may lead to production of gametes with deletions or duplications. (iv) This method is suitable for studies on the survival of genes and genotypes in populations. vi. In distant hybridization transfer of characters is not as simple as in intervarietal crosses. Interspecific crosses are fully sterile between those species which do not have chromosomal homology. Flowers should be selected at proper stage. Now-a-days this method is employed in improvement of both self and cross-pollinated crops where varieties are deficient in one or two aspects. Improvement in yield has also been achieved through the use of wild species in some crops. Intergeneric cross between radish (Raphanus sativus) and caage (Bassica oleracea) of the family Cruciferae was made by Karpechenko in 1928 in Russia. Trials of superior lines are confirmed. Distant crosses are more successful in more closely related species or genera than in less closely related species or genera. The paper concentrates on recent developments of biotechnology use in the seed industry. Crosses between tetraploid species G. hirsutum and G. barbadense and between diploid species G. arboreum and G. herbaceum are fully fertile. 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. Most of the modem cultivars of sugarcane and potato are the derivatives of interspecific hybridization. […] Several problems are associated with distant hybridization. Both these new species are grown for commercial cultivation. It is one of the major drawback of this method. OBJECTIVES OF WIDE HYBRIDIZATION A selection method, which is used in segregating population of self-pollinated species and keeps proper record of plants and progeny selected in each generation is known as pedigree breeding. Transfer of some genes from one species into the genome of the other species is known as introgressive hybridization. diploid (2n = 14), tetraploid (2n = 28) and hexaploid (2n = 42). It can be defined as the artificial cross-pollination between the genetically unlike plants. 5. The advantage of this cross is the use of vigorous hybrid of first generation as female in order to maximize the yield of hybrid seeds as well as to obtain seeds of normal grain size. In some crops (e.g., Jowar, Bajra) the inflorescences of both the parents are enclosed in the same bag. 5. (iii) Sometimes undesirable genes are closely linked with desirable one and get transferred to the new variety. Mol Biol Plants 15(1):3–22 There is occasional seed set in this cross. The first is the Triticale which has evolved from intergeneric cross between Triticum aestivum and Secale cereale. (i) The bulk method is simple, convenient, inexpensive and less labour consuming (no pedigree record is to be kept). The chromosome behaviors in F1 hybrids provide us with the essential genetic basis for chromosome manipulation. Parental plants must be selected from the local areas and are supposed to be the best suited to the existing conditions. There is rarely seed set in this cross. Interspecific crosses are partially fertile between those species which differ in chromosome number but have some chromosomes in common. On the other hand, Tripsacum pollen are unable to produce long pollen tube to reach the ovule of maize. 4. Three crosses were made among three species namely cabbage (Brassica oleracea), rapeseed (B. campestris) and black mustard (B. nigra). Applications of Distant Hybridization: The application of distant hybridization in crop improvement is not an easy task. 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. Similarly, in wheat the cross between Aegilops ventricosa and Triticum aestivum is sterile. 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. Extension of chromosomes into cytoplasm. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. 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). Resistance to various diseases has been achieved in several crops like wheat, cotton, tobacco, sugarcane, potato, strawberry, okra etc. 3. Similarly, most of the modern cultivars of potato are derivatives of interspecific hybrids. 6. These problems pose several difficulties in interspecific or intergeneric gene transfer. 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. Treatment of F1 plants with colchicine resulted in the production of fertile amphidiploid (2n = 52) which was similar to upland cotton (G. hirsutum). Content Guidelines 2. When the F1 plants were treated with colchicine, a fully fertile tetraploid (2n = 48) was obtained which resembled cultivated species (N. tabacum). Biotechnology is the term which uses living organisms to improve plants, modify the product and develop organisms for further uses. ploidy manipulation pistil manipulation, chemical (growth regulator) treatment, bridge crossing, grafting, embryo culture etc. The method is used for the transfer of a dominant gene. Several intergeneric crosses have been made in sugarcane. In the coming season, the stored seeds are sown separately to raise the F1 generation. (ii) Selfing of parents or artificial self-pollination: It is essential for inducing homozygosity for eliminating the undesirable characters and obtaining inbreeds. Sometimes, distant hybridization and polyploidy lead to creation of new crop species. (iii) Selection is done by nature only and it increases the frequency of superior types in the population. Seed production and processing technologies. Seeds are space planted and single plant selection is done (F7 generation). Teosinte has been used to improve maize for silage. In case of recessive gene transfer, a slightly different procedure is followed. The CMS has been transferred to cultivated species of these crops. The crosses between different species of the same genus or different genera of the same family are also known as distant hybridization or wide crossing. Normally 20-50 families may be retained at the end of F5 generation. Cytoplasmic male sterility (CMS) is an economic device for hybrid seed production. diploid (2n = 24), tetraploid (2n = 48) and hexaploid (2n = 72). In such situation either reciprocal cross should be made or the style should be cut to normal size before pollination. The following techniques are useful in obtaining zygotes from distant crosses: Genetic differences exist among parents in a species for cross compatibility. Intergeneric crosses of barley (Hordeum) were attempted with some species of Avena, Phleum, Dactylis, Alopercunis, Triticum. The plants of F1 generation are progenies of cross seeds and therefore are hybrids. Role of interspecific and intergeneric hybridization. 1) Intervarietal Hybridization: The parents involved in hybridization belong to the same species. In crop improvement programmes, intervarietal hybridization is the most commonly used. 2. It is summarized in Figs. Several modern cultivars of sugarcane have been developed from crosses of Saccharum officinarum with S. spontaneum or S. barberi. The bags may be made of paper, butter paper, glassine or fine cloth. biotechnology is included in the crop improvement and genetic resources program. The main cause of hybrid sterility is lack of structural homology between the chromosomes of two species. Wide or distant hybridization has been widely used as an important tool of chromosome manipulation for crop improvement. Role of environment is almost negligible. The intervarietal crosses may be simple or complex depending upon the number of parents involved. The bridge cross is a complicated procedure and is more successful for transfer of monogenic dominant characters. Selected material becomes so large that handling of the same becomes very difficult. Types 4. Breeder does not require to handle large populations. There are three main reasons of cross incompatibility, viz. Therefore, crop improvement through biotechnological approaches, appears to be time effective and alternative approach. (The process may be repeated until the desired period of homozygosity is achieved. There are two cultivated species of oat, viz. Distant hybridization Somatic hybridization; ... function and role in the regulation of a biological system. What are the characters Mendel selected for his experiments on pea plant? Meiosis in F1 leads to formation of 24 bivalents and 12 univalents. The F1 hybrid 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. Content 1) Introduction 2) History of Distant Hybridization 3) Features 4) Barriers associated with Distant Hybridization 5) Techniques for production of Distant Hybrid 6) Role of Wide crossing in crop improvement 7) Limitations of Distant Hybridization 8) Achievements