The utilities of Citrus tissue culture
Abstract
Citrus is the third most important fruit crop in the world after apple and bananas, and the total a rea cultivated with the various Citrus cultivar covers over 7.2 million hectares, yielding total annual production of approximately 100 million metric tons of fruit. The genus Citrus possesses several undesirable characteristic including salt and cold sens itivity they are also susceptible to diseases caused by fungi, bacteria and viruses. Despit substantial genetic diversity and interspecific fertility, the genus Citrus includes some of the most difficult species to breeding. For example, most species are highly heterozygous and produce progeny that segregate widely for many characters when crosses are made. The juvenile periods are often very long, self - and cross -incompatibility and pollen and/or ovule sterility are relatively common, and the presence of a dventitious somatic embryos in the nucellus of developing ovules of the most of Citrus greatly limits hybrid production. Genetic transformation is an alternative to overcome these difficulties. For successful transformation, regeneration of whole plants fr om the transformed cells is a prerequisite. On the other hand production of virus – free plants, development of new cultivars, and production of seedless fruit, production of flavonoid, micropropagation, germplasm conservation and cryopreservation are the other utilities of in vitro culture of Citrus .
Keywords
Download Options
Introduction
Tissue culture is the in vitro aseptic culture of cells, tissues, organs or whole plant under controlled nutritional and environmental conditions (Thorpe 2007) often to produce the clones of plants. It is clear that in vitro culture is an essential component of plant – biotechnology, offers innovative approaches in several research areas (Annarita and Laura 2012). The importance of plant cell, tiss ue and organ culture is more cleared when it includes in major fruit crop in vitro culture regarding to micropropagation, the induction of somatic embryogenesis, the improving of methodologies through the analysis of medium components, and the use of addit ives to increase the frequency of regeneration and the production of the in vitro cultures for the important species such as species belong to genus Citrus . The genus Citrus is cultured in more than 100 countries making it one of the most important commerc ial fruit crops in terms of economic value and human nutrition (Barlass and Skene 1986). Citrus is the most important fruit crop in the world and is produced in all five continents and it is often regarded as golden fruit or queen of all fruits (Nito 1996) .
Despite substantial genetic diversity and interspecific fertility, the genus Citrus includes some of the most difficult species to breed (Gmitter et al., 1992 & Perez – Molphe – Balch and Ochoa – Aljeo 1998). This is due to several obstacles for convent ional breeding. For example, most species are highly heterozygous and produce progeny that segregate widely for many characters when crosses are made. The juvenile periods are often very long, self – and cross – incompatibility and pollen and/or ovule ster ility are relatively common, and the presence of adventitious somatic embryos in the nucellus of developing ovules of the most of Citrus greatly limits hybrid production (Perez – Molphe – Balch and Ochoa – Aljeo 1998 & Moore et al., 1993). Genetic transfor mation is an alternative to overcome these difficulties. For successful transformation, regeneration of whole plants from the transformed cells is a prerequisite (Duan et al., 2007). In this review some of the mos t important utilities of Citrus tissue cult ure that are based on result of diffe rent experiments in this field were explained .
Conclusion
Like the vast majority of genera and s pecies of plants, especially economically important genera and species, different species of Citrus genius need to improvement. Citrus improvement by conventional methods due to difficulties such as has limitations that all of them solve by modern methods of biotechnology or in other words transformation. Low plant regeneration frequencies especially for many of the economically important Citrus species is the most important difficult within this almost new and advanced method. So the progression of tissue culture methods leads to solving these problems.
