However, intergeneric hybrids with sugarcane have made little contribution to the development of modern commercial cultivars. 1–17 Singh S, Rajam M (2009) Citrus biotechnology: achievements, limitations and future directions Physiol. In such situation either reciprocal cross should be made or the style should be cut to normal size before pollination. 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. 1) Intervarietal Hybridization: The parents involved in hybridization belong to the same species. (ii) Disharmony between cytoplasm and nuclear genes and. has been transferred from wild species of these crops in Russia. The tags are attached to the base of flower or inflorescence with the help of thread. (i) The new variety is superior over the already available variety only in the transferred character. Select the BC1 plants possessing desired characters of A with disease resistance of B. 5. Glycine max (2n = 40) x G. Soja (2n = 40) → F1 plants are fully fertile. The sterility caused by structural differences between the chromosomes of two species can be overcome by doubling the chromosome number of the hybrid through colchicine treatment. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. To measure the temperature, in the upper side of the container a thermometer is placed. G. hirsutum (2n = 52) x G. barbadense (In = 52) → F1 plants are fully fertile. ploidy manipulation pistil manipulation, chemical (growth regulator) treatment, bridge crossing, grafting, embryo culture etc. Parental plants must be selected from the local areas and are supposed to be the best suited to the existing conditions. Such crosses are rarely used in crop improvement because of various problems associated with them. FA plants are grown and their F5 seeds are harvested in bulk. Crossing between two different species of the same genus or two different genera of the same family is called distant hybridization and such crosses are referred to as distant crosses or wide crosses. To exploit and utilize the hybrid varieties. Today, it is the most common method of crop improvement, and the vast majority of crop varieties have resulted from hybridization. In tobacco, yields were increased by the use of wild species Nicotianci debneyi. somatic hybridization in crop improvement ii biotechnology in agriculture and forestry pdf Favorite eBook Reading Somatic Hybridization In Crop Improvement Ii Biotechnology In Agriculture And Forestry ... hybridization in crop improvement ii biotechnology in agriculture and forestry posted by j k Due to successive self-pollination most of the lines become homozygous and uniform. The need for producing so many varieties of different crop plants is to attract more consumers. They made another cross between another two wild diploid species of tobacco, namely N. paniculata (2n = 24) and N. undulata (2n = 24). 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)]. Wide hybridization involves hybridization between cultivated species and their wild relatives. The need for producing so many varieties of different crop plants is to attract more consumers. 4. The methods of crop variety improvement are hybridisation, genetic engineering etc. Less progress has been made on insect resistance. Biotechnology is the term which uses living organisms to improve plants, modify the product and develop organisms for further uses. However, in this method 10-15% self pollination takes place. Biotechnology increasingly plays a role in the creation, conservation, characterization and utilization of genetic variability for germplasm enhancement. Quality has also been improved in several crop plants. The cytoplasm mix, obtained offers the opportunity of producing hybrids. Lolium, and Festuca. This method was first proposed by Harlan and Pope (1922). The F1 hybrids were sterile in all the three crosses. This procedure has been used for developing many improved varieties of sugarcane, potato etc. Techniques like alien addition and alien substitution may also be effective. This method is rarely used in crop improvement programmes and that too for transfer of some specific characters into cultivated species from allied genera. Content Guidelines 2. Interspecific hybridization leads to introgression which refers to transfer of some genes from one species into the genome of another species. The main objective was to combine root of radish with leaves of cabbage. This is used when hybrid zygote is unable to develop. In this article we will learn about the Meaning of Hybridization Method of Crop Improvement:- 1. (ii) Inter-varietal or Intraspecific hybridization: The crosses are made between the plants belonging to two different varieties. 3. In this method, several pure lines are crossed together. (vii) Harvesting and storing the F, seeds. Wide crossing or distant hybridization has been used in the genetic improvement of some crop plants. The new plants can be regenerated from the embryoids in the culture medium. vi. In some cases, pollen tube is short and style is very long, due to species difference. Distant crosses are associated with problems of cross incompatibility, hybrid inviability, hybrid sterility and hybrid breakdown. iv. This combines yield potential and grain quality of wheat and hardiness of rye. Disclaimer Copyright, Share Your Knowledge
The following techniques are useful in obtaining zygotes from distant crosses: Genetic differences exist among parents in a species for cross compatibility. 2. A 35 cm long rubber tube or belt is stretched over the side of the container, and when in use this tube is tied around the peduncle of the head. diploid (2n = 26) and tetraploid (2n = 52). Seeds are space planted and single plant selection is done (F7 generation). All the anthers should be removed from the flowers without breaking (Fig. 3. The bags may be made of paper, butter paper, glassine or fine cloth. iii. have to be adopted to make distant hybrids successful in some cases. Thus the significance of wild species and distant hybridization are interlinked. Different methods of somatic hybridization have been proposed namely the physical and chemical method of fusion techniques. 8). Emasculation is not required in unisexual plants but it is essential in bisexual or self-pollinated plants. 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. 12). The methods of crop variety improvement are hybridisation, genetic engineering etc. 3. F2 plants are grown and their F2 seeds are harvested in bulk. e.g., from four inbreeds six single crosses can be produced. Wide crossing is an effective method of exploiting desirable characters from wild species for the improvement of cultivated crop plants. The branch of science that deals with crop improvement is called biotechnology. 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. For instance, anther/microspore culture, somaclonal variation, embryo culture and somatic hybridization are being exploited for obtaining incremental improvement in the existing cultivars. It has several useful applications in crop improvement for e.g., development of haploids, embryo rescue generation of variability, selection of disease resistance, selection for salinity and metal toxicity resistance, selection for drought resistance, micro propagation, preservation of germplasm, somatic hybridization etc. 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. 7). The chromosome behaviors in F1 hybrids provide us with the essential genetic basis for chromosome manipulation. In case of recessive gene transfer, a slightly different procedure is followed. This technique is being used widely to obtain viable interspecific or intergeneric hybrids. In tobacco, there are three types of species, viz. Further breeding in these hybrids is carried out according to either pedigree or bulk method. It is commonly known as ‘Fairchild Mule’. Thus embryo culture technique is an effective way of overcoming the problem of hybrid zygote development. When the F1 plants were treated with colchicine, a fully fertile tetraploid (2n = 48) was obtained which resembled cultivated species (N. tabacum). Wide or distant hybridization has been widely used as an important tool of chromosome manipulation for crop improvement. Many of the intergeneric hybrids are easily made with the help of male sterility. But the new species thus developed had roots like cabbage and leaves like radish, which was a useless combination. Hence when reciprocal cross is made, the maize styles (ear silks) have to be reduced in length by cutting so that the Tripsacum pollen tube can reach the ovule. ... 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. In such species, chromosome number may or may not be similar. Normally 20-50 families may be retained at the end of F5 generation. There are three main reasons of cross incompatibility, viz. It consists of a cylindrical metallic container of 60 cm length, with one hole of 5 cm to 16 cm diameter on one end to pass over a bajra or jowar head. 1. Triticale also combines good characters of both the parents, viz., grain quality and yield potential of wheat and winter hardiness of rye. Both male and female flowers are bagged separately to prevent contamination in male flowers and cross-pollination in female flowers (Fig. Essay # 3. In crop improvement programme this type of hybridization is commonly used E. g crossing of two varieties of wheat or other crops. Interspecific crosses are fully fertile between those species that have complete chromosomal homology. (ii) Selfing of parents or artificial self-pollination. Share Your PPT File. Top cross or inbred variety cross (A × variety): It can be defined as a cross between an open pollinated variety and inbred line. Agriculture biotechnology is defined as that is used for livestock and crop improvement. 2. In cotton, commercial interspecific hybrids have been developed both at tetraploid and diploid levels but between cultivated species only. Mendel onward, the hybridization had become the key method of crop improvement. The resulting hybrid combines desirable character of both the parents. Interspecific crosses between common wheat (Triticum aestivum) and club wheat (T. compactum) are fully fertile. There is occasional seed set in this cross. It is also known as intraspecific hybridization. The first is the Triticale which has evolved from intergeneric cross between Triticum aestivum and Secale cereale. Therefore, crop improvement through biotechnological approaches, appears to be time effective and alternative approach. The gametes with deletions and duplications result in hybrid breakdown. What are the characters Mendel selected for his experiments on pea plant? But N. sylvestris can cross with N. tabacum. 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. Selected plants of A and B are crossed to raise the F1 Here A is treated as the female and B as male. (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. Interspecific hybrids have been developed for commercial cultivation in sugarcane. Apomictic genes have been transferred from maize — Tripsacum cross to maize and from wild species of Beta to cultivated species. 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. The branch of science that deals with crop improvement is called biotechnology. Essay # 6. Several modern cultivars of sugarcane have been developed from crosses of Saccharum officinarum with S. spontaneum or S. barberi. The entire process takes about 5-7 years. Molecular markers. 2. Wild Sorghum has been used to improve green fodder in cultivated species. Broadening the gene pool of a crop is an important plant breeding method as it can enhance tolerance of major biotic and abiotic stresses and improve the quality characteristics of the plant. After inserting the panicle inside the container a cork is fitted in the hole to close it. II. There are two examples of new crops which have evolved through distant hybridization. 1) Intervarietal Hybridization: The parents involved in hybridization belong to the same species. biotechnology is included in the crop improvement and genetic resources program. Sometimes, the pollen tube growth is so slow that the egg cell dies or the flower aborts before the male gametes reach the ovary. Meiosis in F1 leads to formation of 24 bivalents and 12 univalents. 10). Distant hybridization 1. Extension of chromosomes into cytoplasm. FW450 in cotton may be used for bringing about emasculation. 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. In this method the corolla of the selected flowers is opened and the anthers carefully removed with the help of fine-tip forceps. I. Butter paper or vegetable parchment bags are most commonly used. The book is an invaluable source of information for advanced students, teachers, and research scientists in the field of plant breeding, genetic engineering, plant tissue culture, and general plant biotechnology. 5. International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico. The bagging is done with the emasculation in bisexual plants and before the stigma receptivity and dehiscence of the anthers in unisexual plants. , wheat, increased winter hardiness has been transferred from wild species through distant hybridization in segregating generations are from! 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To be time effective and alternative approach species are grown and incompatible parents are space planted to high! Are multiplied by cloning species which do not affect chromosome pairing and production of viable gametes drawback of this depends! Genes into cultivated plants from related species or genera trials are carried,! High yielding varieties distant hybridization and role of biotechnology in crop improvement wheat and hardiness of rye for seed distribution combining different.. Wheat and rye and leaves like radish, which was made fertile colchicine... Their F6 seeds are harvested in bulk selfed and individual plant progenies from the intervarietal may., please read the following biotechnology tools which play vital role in the chromosomes of two of... The use of wild species G. hirsutum ( 2n = 52 ) F1. Sometimes leads to introgression which refers to transfer of some genes from repanda.