International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Impact Factor (2012): 3.358 Volume 3 Issue 11, November 2014 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Genetic Fidelity in Micropropagated Plantlets of Anacardium occidentale L. (Cashew) an Important Fruit Tree Shashi Kiran Nivas 1 , L. D`Souza 2 1, 2 Laboratory of Applied Biology, St. Aloysius College, Mangalore 575003, India Abstract: The meristem and axillary bud tissue culture were considered to be an ideal horticultural tool to generate morphologically and genetically true to type plants. In tissue culture derived plants of Anacardium occidentale L (cashew) variations in morphological traits like height and girth of the stem, the shape of the leaves and plagiotrophy are seen in the plants generated from the same cotyledonary nodes. In our experiments the multiple shoots were induced from cotyledonary nodes without the addition of growth regulators, without an intervening callus and within one generation; yet they show considerable amount of variation in morphology. Since no growth regulators were used or frequent subcultures were made it is suggested that the variation is due to stress induced by tissue culture procedures. Keywords: Multiple buds, Cotyledonary nodes, Morphology, Genetic variation, Plagiotrophy, Somaclonal variation. Abbreviations: IBA- Indole -3- butyric acid, IAA- Indole Acetic Acid. 1. Introduction Anacardium occidentale L (Cashew) is an important nut crop of economic and social importance for India. It is a source of the much needed foreign exchange and provides work for uneducated rural women. The production of raw nuts is not enough to meet the demand of the international market and to provide work for the women all through the year. This is due to the low yield of the trees grown at present as well as the loss of crop due to insect pests. Conventional methods for improvement of cashew can be supported by information on the process of germination, organogenesis and variation. Variation among plants regenerated from tissue culture is termed ‘somaclonal variation’ (Larkin and Scowcroft, 1981). Some workers consider somaclonal variation to be caused by the in vitro culture system itself; others consider it to be the expression of pre-existing physiological or genetic variation in somatic cells (D`Amato, 1985; Swartz, 1991). Several factors have been found to influence the level of somaclonal variation. For example, the regeneration system used, the cryopreservation protocol, the culture conditions and the number of subcultures which the cultures have passed through. (D`Amato, 1985; de Klerk, 1990; Harding, 1991; Harding, 1997; Jain et al. 1998; Aronen et al. 1999; Rani and Raina, 2000; Hao and Deng, 2002; Zhai et al. 2003). Other specific procedures which are reported to induce somaclonal variation are protoplast isolation (Li et al. 1994) or gene transfer (Bregitzer et al. 1998). Some species or clones are found to be more susceptible to somaclonal variation than others (Karp, 1989; Israeli et al. 1996). According to Larkin and Scowcroft, 1981, somaclonal variation can be limited by selecting the correct explant source, developing in vitro medium supplement with minimal amounts of growth regulators, particularly BAP , avoiding exceeding the number of subculture cycles to beyond eight and avoiding frequent subculture. Although somaclonal variation is undesirable in micropropagation, it can be a useful source of new variability in fruit crops where long generation time hinders conventional breeding (Hammerschlag, 1992). Variation in somaclones for karyotype, isoenzyme pattern, precocity for bearing, ploidy level, growth, yield, quality, pigmentation, disease resistance and resistance to adverse soil and climatic conditions have all been reported in different plants ( Patil and Nevale, 2000). In general in vitro conditions can be extremely stressful on plant cell, and may set in motion highly mutagenic processes during explant establishment, callus induction, maintenance, embryo development and plant regeneration (Lorz et al. 1988). 2. Materials and Methods Plant material Mature seeds of cashew of the variety Ullal 3 obtained from Cashew Research Station of the University of Agricultural Sciences, Ullal were used for the experiment. Sterilization of plant material The nuts were kept under flowing water for 2 hours to remove the surface grouse, soil particles and also fungal spores prior to chemical sterilization so as to reduce contamination of cultures considerably. The nuts were then surface sterilized using 0.1% Bavistin (Carbendizim) for 45 minutes and in 0.1% mercuric chloride and 0.1% sodium lauryl sulphate for 20 minutes. After sterilizing they were rinsed thoroughly with sterile water till all the surface sterilants were washed away. They were then soaked in sterile distilled water for three days to soften the hard seed coat. The soaked nuts were opened under laminar air flow Paper ID: OCT141442 2142