In vitro plant regeneration in six cultivars of Capsicum spp. using different explants

Abstract

In vitro regeneration from leaf, cotyledon and hypocotyl explants of six cultivars belonging to three species of Capsicum was achieved by direct organogenesis. The cultivar Umorok showed the best response while Meiteimorok, Haomorok, Mashingkha and Uchithi showed intermediate response and the cultivar Chiengpi was the least responsive. Leaf and cotyledon explants regenerated more shoots than hypocotyl explants and the maximum number of shoots were produced on Murashige and Skoog (1962) medium containing 8.8 µM 6-benzylaminopurine (BAP) with 11.4 µM indole-3-acetic acid (IAA). Elongation of shoot buds derived from different explants was achieved on medium containing 2.8 µM IAA and the elongated shoots were rooted on medium containing 2.8 or 5.7 µM IAA and 2.4 or 4.9 µM indole-3-butyric acid (IBA). Four-week old rooted plantlets were hardened and transplanted to the soil. The plantlets showed 90 % survival during transplantation.Additional key words: bud induction, Capsicum annuum, C. chinense, C. frutescens, direct organogenesis, micropropagation. ⎯⎯⎯⎯Chillies are the fruits of the genus Capsicum which account for about 22 % of total global spices trade composition. Besides being a source of hot spice and natural plant colour, chillies are also good sources of capsaicin and are used in pharmaceutical industries. In Manipur (23º47΄ -25º41΄ NL; 93º61΄-94º47΄ EL; 750-3 600 m asl; 1 600 -3 430 mm annual rainfall), six cultivars of Capsicum are cultivated in different agroclimatic areas. The fruits of Capsicum annuum L. are generally mild and used in curried dishes while those of C. chinense Jacq. and C. frutescens L. are highly pungent and used in hot sauces. A major constraint facing the crop in the region is its seed storage due to high atmospheric humidity and the high incidence of seed-borne fungal diseases. Propagation of plants through tissue culture offers a unique advantage over conventional propagation methods such as rapid multiplication of valuable genotypes, expeditious release of improved cultivars, production of disease-free plants, non-seasonal production, germplasm conservation and facilitating their easy exchange. In chilli, several procedures are available for inducing in vitro plant regeneration using leaf, cotyledon and hypocotyl explants (Gunay and ,b). However, several of these reports suggest a strong influence of genotype on the regeneration process (Ochoa-Alejo and Ireta-Moreno 1990, Szasz et al. 1995, Christopher and Rajam 1996, Ramirez-Malagon and Ochoa-Alejo 1996. The present research, involving culture of leaf, cotyledon and hypocotyl explants of six chilli cultivars was undertaken to determine the regeneration potential of the genotypes and to develop efficient in vitro plant regeneration protocols for the six economically important cultivars.Seeds of the six cultivars of Capsicum belonging to three species (Capsicum annuum L. cvs. Meiteimorok and Haomorok, Capsicum chinense Jacq. cvs. Umorok and Chiengpi, Capsicum frutescens L. cvs. Mashingkha and Uchithi) were extracted from fresh ripe...

In Vitro Shoot Bud Differentiation from Hypocotyl Explants of Chili Peppers (Capsicum annuum L.)

“…The results of the above indicate that the plant hormonal combination of 4 mg/l (BAP) and 0.5 mg/l (IAA) was better than any other combination. The results are in agreement with earlier reports of Gunay and Rao (1978); Rajam (1994, 1996); Ramage and Leung (1996); Sanatombi and Sharma (2008). This may be due to auxins or cytokinins used alone or in combination, which is supposed to be the result of the promotion of biosynthesis or inhibition of degradative metabolism, theory shared also by Singh and Shukla (2001).…”

“…Even though other Solanaceae members easily undergo morphogenesis, chili was found to be highly recalcitrant (Ochoa-Alejo and Ramirez-Malagon, 2001;Steinitz et al, 1999). The regeneration capacity of chili plants has been carried out successfully from hypocotyl explants (Borychowski et al, 2002;Rajam, 1994, 1996;Fari and Czako, 1981;Gunay and Rao, 1978;Mok and Norzulaani, 2007;Rodeva et al, 2006;Sanatombi and Sharma, 2008;Singh and Shukla, 2001). However, many of these reports suggest a strong influence of the genotype on the regeneration process (Christopher and Rajam, 1996;Ochoa-Alejo and Ireta-Moreno, 1990;Ramirez-Malagon and Ochoa-Alejo, 1996;Szasz et al, 1995).…”

An improved plant regeneration and Agrobacterium - mediated transformation of red pepper (Capsicum annuum L.)

“…The callus induction at the cut end of cotyledonary leaves and leaf discs was observed and thus we preferred hypocotyls for further experiments. In pepper tissue culture, BAP has been highly effective in shoot bud induction than other cytokinins (Gunay and Rao 1978;Joshi and Kothari 2007;Sanatombi and Sharma 2008). The earlier reports of red pepper regeneration emphasized on a balanced auxin/cytokinin ratio for multiple shoot buds induction (Steinitz et al 1999).…”

“…has been reported for diverse explants such as cotyledons (Gunay and Rao 1978;Ebida and Hu 1993;Manoharan et al 1998;Golegaonkar and Kantharajah 2006), hypocotyls (Gunay and Rao 1978;Ramirez-Malagon and Ochoa-Alejo 1996), leaf discs (Sanatombi and Sharma 2008) and nodal segments (Ahmad et al 2006). However, these reports are genotype-specific and consequently, the regeneration protocol as well as transformation procedure need to be established for each commercial cultivar for exploiting the potential of genetic engineering.…”

“…Cytokinins, in supplement with auxins, have been shown to induce shoot buds proliferation from different types of explants in various plant species. Almost all the protocols of red pepper regeneration using hypocotyls rely on both the cytokinins and auxins (Gunay and Rao 1978;Sanatombi and Sharma 2008). However, Capsicum is known to have high endogenous auxin content and therefore, the exogenous supply of auxins induces callus formation instead of shoot buds (Christopher and Rajam 1994).…”