An establish practice today, crop breeding developed along with human development. As our ancestors slowly and gradually evolved from gathering food to developing permanent sources of food, crop breeding became a key practice in the world today. Humans began selecting and disseminating a wide range of vegetables, fruits, and food grains to feed their ever expanding population. One of which are the citrus fruits. For more than a century, geneticists and citrus breeders have pursued various developmental experiments on new citrus cultivars. With a better world scientific society today, the International Society of Citriculture has presented vital information on the genetic improvements pertaining to citrus breeding programmes.
Citrus Breeding and Requirements
Citrus fruits such as oranges, sweet lime, grapefruit, limes, tangerines, lemons, and mandarins are grown in more than 100 countries across different regions. With biotechnology entering the commercial crop breeding industry, citrus breeding programmes are now found in many parts of the world. A good example is the mandarin hybrids such as tangelos that were cultivated through breeding programmes conducted in the United States. Another example is the three mandarin varieties namely, one of which is called Kinnow mandarin, were released by the Citrus Research Center. The breeding process is growing at a good pace with expected effect on the citrus industry in the future.
Citrus fruit breeding depends on the requirements of the specific region. World citrus breeding programmes vary in accordance with certain objectives, such as rootstock breeding. For example, if an objective is considered a high-priority in some regions it may be considered less important in some other regions. The world citrus industries have begun benefitting from genetic improvements that has led to the release of scion cultivars and superior new rootstock. Improvements in citrus fruit productivity, pest control, disease resistance, tolerance to environmental stress, and characteristics of fruit quality are expected to result in greater economic gain to citrus fruit cultivators.
Molecular Genetics and Mutation Breeding
Citrus genetic improvement based on molecular genetics involves molecular techniques that manipulate genes at the DNA or RNA level. Genes are isolated from other citrus sources for direct incorporation into commercial cultivars. The existing genes are modified to produce certain changes in the characteristics of the citrus plant. The objective of this genomic research is to develop a more consumer and environment friendly hybrids. In addition, this research elaborates the ability of molecular genetics to modify certain very specific characteristics traits of a citrus fruit in a powerful way. Mutation breeding is the development of new citrus cultivars. After identifying and evaluating the desired trait, the container with the mutated cultivar will be released. The aim of mutant breeding is to retain the characteristics features of the existing cultivar and only correct the specific defect or defects in it. Random mutations occur with tissues are exposed to mutagenic agents with either no or undesirable effects. So, screening of larger population is important to find the desired mutation.
Mutation breeding depends on the common targets in mutation include pollens, seed, stem, and embryo.
The basic elements involved in the genetic improvement process for citrus include a transgenic plant production, which is basically the core lab, genetic variation sources such as seed introductions, sexual hybrids, natural mutants, somatic cells, somaclones, irradiated budlines, somatic hybrids, and molecular genetics. The next step is the selection and screening the trait followed by the replicated field trials, which include horticulture evaluation, regional sites, planting dentistry, pests and disease control, and applying appropriate rootstocks. The last step is the release of the genetically improved citrus with appropriate germplasm to homeowners and cost and value of genetic engineering. The commercial industries for evaluation protection.
Haploid plants have had interesting applications in citrus genomics and genetics. Grafting the shoots in vitro allowed the regeneration of several citrus plants.
Likewise, in somaclonal variation also followed an interesting approach toward citrus improvement. When the somaclonal buds were drafted in vitro, scientists were able to recover more than 450 plant types that were under field evaluation. Citrus improvement through the irradiation attempts to the number of seeds that are produced by superior genotypes, especially in mandarins. Today, more stable mutants are being produced. With new approaches and effective methods, citrus breeding programmes have a broader reach and a better understanding.
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