Chili pepper is an important horticultural crop that can surely benefit from plant biotechnology. However, although it is a Solanaceous member, developments in plant cell, tissue, and organ culture, as well as on plant genetic transformation, have lagged far behind those achieved for other members of the same family, such as tobacco (Nicotiana tabacum), tomato (Lycopersicon esculentum), and potato (Solanum tuberosum), species frequently used as model systems because of their facility to regenerate organs and eventually whole plants in vitro, and also for their ability to be genetically engineered by the currently available transformation methods. Capsicum members have been shown to be recalcitrant to differentiation and plant regeneration under in vitro conditions, which in turn makes it very difficult or inefficient to apply recombinant DNA technologies via genetic transformation aimed at genetic improvement against pests and diseases. Some approaches, however, have made possible the regeneration of chili pepper plants from in vitro-cultured cells, tissues, and organs through organogenesis or embryogenesis. Anther culture has been successfully applied to obtain haploid and doubledhaploid plants. Organogenic systems have been used for in vitro micropropagation as well as for genetic transformation. Application of both tissue culture and genetic transformation techniques have led to the development of chili pepper plants more resistant to at least one type of virus. Cell and tissue cultures have been applied successfully to the selection of variant cells exhibiting increased resistance to abiotic stresses, but no plants exhibiting the selected traits have been regenerated. Production of capsaicinoids, the hot principle of chili pepper fruits, by cells and callus tissues has been another area of intense research. The advances, limitations, and applications of chili pepper biotechnology are discussed.

In vitro chili pepper biotechnology

The biodiesel plant, Jatropha curcas L. was micropropagated using nodal explants on MS supplemented with BAP (1.5 mg/l), Kn (0.5 mg/l) and IAA (0.1 mg/l). Somatic embryos were induced directly from green cotyledon explants on MS fortified with 2 mg/l of BAP. The results of histological studies showed that several layers of meristematic cells participated in the formation of somatic embryos. Rooting was effectively achieved on MS supplemented with IAA at 1.0 mg/l. The subsequent hardening experiment showed that the commercial medium containing a mixture of decomposed coir waste, perlite and organic compost in the ratio of 1:1:1 by volume was most effective, 80% plantlets survived. Key words: Jatropha curcas , Nodal explants, Cotyledons, Somatic Embryos, Multiple shoot formation D.O.I. 10.3329/ptcb.v17i2.3234 Plant Tissue Cult. & Biotech. 17 (2): 137-147, 2007 (December)

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In vitro Propagation of the Biodiesel Plant Jatropha curcas L.

Rauwolfia tetraphylla L. is an important medicinal plant species which is well known for its pharmaceutically important alkaloids. In the present study, we are reporting about its conservation by in vitro clonal multiplication through the standardized protocol of indirect regeneration by using leaf and stem based callus and assessment of genetic fidelity of acclimated plantlets by start codon targeted (SCoT), inter simple sequence repeats (ISSR), and randomly amplified polymorphic DNA (RAPD) marker based analysis. Initially friable callus was induced in maximum amounts (378.7, 323.8, and 412.8 in mg) from leaf, root, and stem explants on Murashige and Skoog (MS) media supplemented with 5.0 mg/L, 3.0 mg/L of 2,4-dichlorophenoxyacetic acid (2,4-D) and 5.0 mg/L of naphthalene acetic acid (NAA), respectively. Shoot regeneration with the maximum number of shoot buds (25 and 20) was obtained from leaf and stem calluses on MS media supplemented with TDZ (0.25 mg/L) + BAP (2 mg/L). The regenerated shoots were rooted successfully with maximum rooting percentage of 98.0 on full strength MS media amended with IAA (1.0 mg/L) and IBA (1.0 mg/L). The regenerated plantlets were hardened using 2:1 ratio of sterile garden soil and sand, followed by acclimatization in field conditions with 86% of survival. SCoT, ISSR, and RAPD primers based polymerase chain reaction (PCR) analysis was carried out to check possible genetic variations in micro propagated plants in comparison with mother plant. Among the ten SCoT (S), ISSR (R), and RAPD (OPA) primers used, S2, R10, and OPA3 has given good amplification with scorable DNA bands. The results revealed that the regenerated plants did not have any polymorphism with mother plant. Hence, the in vitro regenerated R. tetraphylla plantlets were confirmed as true-to-type.

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Indirect Regeneration and Assessment of Genetic Fidelity of Acclimated Plantlets by SCoT, ISSR, and RAPD Markers in Rauwolfia tetraphylla L.: An Endangered Medicinal Plant

The use of herbicides has revolutionized weed control in many crop production systems. However, with the increasing development of weed resistances to many popular selective herbicides, the need has arisen to rethink the application of chemical weed control. Approaches to maintain the efficiency of chemical weed control include the discovery of new herbicide target sites in plants and the discovery/ synthesis of new, more potent herbicidal molecules. However, these approaches are expensive to execute, take considerably long times to succeed and may lead to increased chemical loads in the environment. Since many existing broad-spectrum herbicides are still effective, an alternative strategy adopted to ensure the safe use of broad-spectrum herbicides in a wide range of crops is the application of biotechnological techniques to engineer crop selectivity to these herbicides. In this review we summarize efforts being made to develop crop herbicide selectivity using biotechnology. Keywords: Biotechnology, herbicide resistance, cell culture, mutagenesis, genetic transformation

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Biotechnology approaches to developing herbicide tolerance/selectivity in crops

The book contains aspects of production, genetics and breeding of Capsicum species with emphasis on fruit quality, yield and its nutritional characteristics among with some specific chapters focusing on breeding and physiological features of potted ornamental Chili and responses to abiotic stress and postharvest of fruits

Production and Breeding of Chilli Peppers (Capsicum spp.)

Somatic embryogenesis and plant regeneration from the cotyledon and leaf explants of Indian Solanum (Solanum surattense Burm. f.), a medicinally important plant, is reported. Embryogenic callus was induced from cotyledon and leaf explants on Murashige and Skoog’s medium fortified with 0.5-8.0 mg/L α-naphthalene acetic acid (NAA) + 0.5 mg/L N 6 benzylaminopurine (BAP). High frequency of somatic embryo formation was found at 6.0 mg/L NAA + 0.5 mg/L BAP and 4.0 mg/L NAA+ 0.5 mg/L BAP in cotyledon and leaf explants, respectively. Secondary somatic embryogenesis was also observed when primary somatic embryos were subcultured on the same somatic embryo induction medium. Well-developed cotyledonary stage embryos were germinated on MS medium supplemented with 0.5 mg/L indole-3-acetic acid (IAA) +1.08.0 mg/L BAP. Maximum percentage (71.2%) of somatic embryo germination and plantlet formation was found at 0.5 mg/L IAA+2.0 mg/L BAP, but they didn’t germinate on ½ MSO and MSO media. The post transplantation survival rate of plants was 65-70%. Plants and flowers formed were morphologically similar to mother plants. The present protocol can be used for genetic transformation experiments in S. surattense.

http://nopr.niscair.res.in/bitstream/123456789/5755/1/IJBT%204(3)%20414-418.pdf

Somatic embryogenesis and plantlet regeneration from cotyledon and leaf explants of Solanum surattense

Somatic embryogenesis and plant regeneration of Capsicum baccatum L.

The effects of atrazine on cotyledon cultures of Capsicum annuum (L.) cv. G4 were investigated with a view of establishing a system for in vitro selection of resistant mutants. At low levels of herbicide produced little growth inhibition, some chlorophyll loss occurred associated with the production of albino shoots. At 20 mg l−1 atrazine bleaching was more pronounced and was accompanied by the development of necrotic spots; however, efficient bleaching was associated with severe suppression of growth. Mutagenized cotyledon explants resulted in production of herbicide-resistant plants on medium containing selective levels of sucrose (0.5%) and atrazine (20 mg l−1). Differential morphogenetic responses were observed when the levels of sucrose (0.5–5%) were altered. Shoot regeneration was maximum in 2 sucrose and the regenerating ability decreased with a further increase in sucrose concentration (3%–5%). However, lowering of sucrose concentration from 2 to 0.5% caused complete bleaching of explants and permitted the selection of herbicide-resistant plants. Complete atrazine-resistant plantlets were obtained after rooting of regenerated green shoots on rooting medium containing 10 mg l−1atrazine, 1.0 mg l−1IAA and 0.5% sucrose. Leaf-segment assay of differentiated plants revealed that all regenerants were resistant to the atrazine. Reciprocal crosses between atrazine-resistant and -sensitive plants showed a non-Mendelian transmission of resistance trait.

Selection of atrazine-resistant plants by in vitro mutagenesis in pepper (Capsicum annuum)

In the present study, genetic variability in 10 commercial chilli pepper varieties viz. Gemini, G-334, Agnirekha, Pusa jwala, Mangala, Black diamond, Sindura, Pusa jyothi, Badiga-2 and Teja (branch), cultivated in the local area of Andhra Pradesh State, India, using random amplified polymorphic DNA (RAPD) markers was examined. Out of thee RAPD markers used for screening 10 chilli pepper genotypes, DNA amplification was observed only with OPAB02; this primer produced monomorphic band in Gemini,G-334, Black diamond and Sindura and polymorphic bands in Agnirekha, Pusa jwala, Mangala, Pusa jyothi, Badiga-2 and Teja (Branch). Genetic variabilty in terms of DNA pattern produced in the above varieties could be used as a marker to distinguish between them. Dendrogram generated by OPAB02 primer showed that the 10 chilli pepper varieties could be grouped into four clusters. Average genetic similarity index revealed 100% similarity between varieties of first cluster, 50% similarity between varieties of second and fourth clusters and 32% genetic similarity between varieties of third cluster. UPGMA cluster analysis will be useful in chilli pepper breeding programmes and germplasm conservation. Since the commercial value of chilli pepper is based on pungency level, future studies are aimed at molecular marker based pungency phenotyping. Keywords : Capsicum annuum, Randomly Amplified Polymorphic DNA, Dendrogram, Polymerase Chain Reaction. African Journal of Biotechnology Vol. 12(30), pp. 4730-4735

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DNA profiling of commercial chilli pepper (Capsicum annuum L.) varieties using random amplified polymorphic DNA (RAPD) markers

Callus cultures of Capsicum annuum cv. G 4 were selected on different concentrations of NaCl and mannitol containing media. Growth, viability and proline content of adapted and unadapted calluses were affected when treated with different osmotica like NaCl (ionic, penetrating) and mannitol (non-ionic, penetrating). The tissues adapted to a low concentration of NaCl (35mM) showed less growth with high proline content compared to the tissues adapted to a low concentration of mannitol (110mM). Proline content was similar in tissues adapted to high concentrations of NaCl (175mM) and mannitol (329mM) but growth in the latter case was relatively low. Growth and viability were subsequently correlated with proline content of the tissues after osmotic treatments. The loss of tissue viability of the adapted calluses was comparatively less than the unadapted callus even after osmotic treatments with 210 mM NaCl and 329 mM mannitol. The adapted calluses retained the capability of regrowth, though at a slow rate and also retained more proline. The results indicated that the effects of different osmotica on plant tissues varied depending upon the physio-chemical nature of the compounds used as stress inducing agents and that the retention and diffusion of proline was altered when the tissues were treated with high concentration of these compounds.

P. Venkataiah

Papers

Somatic embryogenesis and plantlet regeneration from cotyledon and leaf explants of Solanum surattense

Somatic embryogenesis and plant regeneration of Capsicum baccatum L.

Selection of atrazine-resistant plants by in vitro mutagenesis in pepper (Capsicum annuum)

DNA profiling of commercial chilli pepper (Capsicum annuum L.) varieties using random amplified polymorphic DNA (RAPD) markers

Selection and characterization of sodium chloride and mannitol tolerant callus lines of red pepper (Capsicum annuum L.)