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ABSTRACT: Chlorogenic acid (CGA), a product of the phenylpropanoid pathway, is one of the most widespread soluble phenolic compounds in the plant kingdom. Although CGA is known to have important roles in plant function, its relevance in plant de novo organogenesis is not yet understood. With a series of experiments, here we show that CGA has a potential role in shoot, root and root hair development. In the first phase of our investigation, we developed an efficient and novel thin cell layer (TCL) regeneration protocol for Hypericum perforatum which could bridge all the in vitro morphogenetic stages between single cell and complete plant. Tissues at different morphogenetic states were analysed for their phenolic profile which revealed that shoot differentiation from callus tissues of H. perforatum is accompanied by the onset of CGA production. Further, the relevance of CGA in de novo organogenesis was deciphered by culturing highly organogenic root explants on media augmented with various concentrations of CGA. Results of this experiment showed that CGA concentrations lower than 10.0 mg l⁻¹ did not affect shoot organogenesis, whereas, higher concentrations significantly reduced this process in a concentration-dependent manner. In spite of the differential concentration-dependent effects of CGA on shoot regeneration, supplementation of CGA did not have any effect on the production of lateral roots and root hairs. Interestingly, CGA showed a concentration-dependent positive correlation with lateral roots and root hairs production in the presence of α-naphthaleneacetic acid (NAA). When the culture medium was augmented with 2-aminoindane-2-phosphonic acid (AIP), an inhibitor of phenylalanine ammonia lyase (PAL), induction of shoots, lateral roots and root hairs from the explants was significantly affected. Addition of an optimum concentration of CGA in these cultures partially restored all these organogenic processes.
Plant Physiology and Biochemistry 05/2011; 49(8):835-42. · 2.84 Impact Factor
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ABSTRACT: Plant recalcitrance is the major barrier in developing Agrobacterium-mediated transformation protocols for several important plant species. Despite the substantial knowledge of T-DNA transfer process, very little is known about the factors leading to the plant recalcitrance. Here, we analyzed the basis of Hypericum perforatum L. (HP) recalcitrance to Agrobacterium-mediated transformation using cell suspension culture. When challenged with Agrobacterium, HP cells swiftly produced an intense oxidative burst, a typical reaction of plant defense. Agrobacterium viability started to decline and reached 99% mortality within 12 h, while the plant cells did not suffer apoptotic process. This is the first evidence showing that the reduction of Agrobacterium viability during co-cultivation with recalcitrant plant cells can affect transformation.
Planta 06/2008; 227(6):1401-8. · 3.00 Impact Factor
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ABSTRACT: St John’s wort (Hypericum perforatum) is a valuable plant used as a herbal remedy or in phytopharmaceutical drugs to treat a variety of physical ailments. Much
research has been performed to study the biochemical production of secondary metabolites of in vitro cultured plants or organs. However, all of these studies have looked at the regeneration of plants from explants in only
one genotype. In addition, no study has revealed the mechanism of plant regeneration in H. perforatum, i.e. organogenesis or somatic embryogenesis. We found that different genotypes Helos, Topas, Elixir, and Numi responded
similarly to regeneration medium. The regeneration responses (i.e. callus, root, or shool production) of identical explants
from different genotypes were similar. However, the source of explant material (leaves, hypocotyls, and roots) from the same
genotype had significant effects on the response to media and plant regeneration frequency. Using scanning electron microscopy
and light microscopy, the progress of organogenesis and embryogenesis under similar culture conditions was recorded. Root
segments were the most responsive explants, producing the maximum number of shoots per explant of all the genotypes.
In Vitro Cellular & Developmental Biology - Plant 06/2006; 42(4):324-330. · 1.50 Impact Factor
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Planta Medica, v.73, 869-870 (2007).
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Phytochemistry, v.70, 60-68 (2009).
