Effect of interaction between different plant growth regulators on in vitro shoot multiplication of Citrus latifolia Tan. (persian lime)
Abstract
In this paper a shoot multiplication is described for Citrus latifolia Tan. (persian lime) using nodal segment explants of young one – old – year trees by two different pathways contain with and without callusing phase. The best result for multiple shoot formation and regenerated shoot formation was 3.2 and 2.6 shoots per explants with 4.44 µM BA plus 0.053 µM NAA and 4.44 µM BA plus 0.049 µM IBA respectively. Alike shoot regeneration, shoot elongation was occurred in medium with 4.44 µM BA and 0.049 µM IBA. Mi cropropagated and regenerated plants are under other experiments. Abbreviation: BA – 6 benzylaminopurine; IBA – Indole acetic acid; NAA – Naphtalene acetic acid; PGRs – Plant Growth Regulators.
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Introduction
Accordant worldwide Citrus species are the most widely grown fruit crops in Iran. They contain vitamin C that is very useful for human nutrition. Also their fruits are important source of volatile oils, limonene, α-terpinene, β-terpinene, citral cumarins, bioflavonoids, vitamins, a nd mucilage (Rathore etal., 2006). Beside apples and bananas, Citrus fruits are the most important fruit crops (FAO 2001). Also it is clear that the sustainable development of the Citrus industry is mainly dependent on a continuous supply of new and impro ved cultivars (Perez – Tornero etal., 2010). For the Citrus industry to improve fruit quality and reduce biotic and abiotic stresses are major breeding objectives at any time (Wenwu etal., 2007). Citrus varieties are propagated by both sexual and asexual methods. Generally, rootstocks are propagated sexually through seeds, while most of the commercial varieties are propagated by various asexual methods (Chaudhary 1994). These conventional techniques are also not free from risk of perpetuating in-born pat hogens. However in vitro micropropagation technology can overcome some constraints to Citrus improvement and cultivation, and can increase fruit quality and resistance to diseases and environmental stresses (Gresser 1994). Also micropropagation systems wi th high multiplication rates are not only an important asexual method that can be used for the production of clonal plants, but also form the basis for the introduction of genetic variation by genetic transformation or mutagenesis. The genetic transformati on of Citrus has been widely studied as a tool to generate transgenic plants with enhanced tolerance of biotic (Cardoso etal., 2010; He etal., 2011 and Ali etal., 2012) and/or abiotic stresses (Bunnag and Tangpong 2012) . In both cases, is necessary to be able to regenerate viable shoots, which can be propagated, by either organogenesis or somatic embryogenesis (Perez – Tornero etal., 2010).
In this paper a protocol for cloning of Citrus latifolia Tan. (persian lime) using nodal explant was described. It should be noted that according to Iranian researchers that used graft inoculation and PCR methods, persian lime was tolerant to Candidatus Phytoplasma aurantifolia . Candidatus Phytoplasma aurantifolia is a serious threat to lime and other susceptible Citrus trees in southern Iran (Salehi etal., 2005).
