Structural and chemical study of callus formation from leaves of Rubia tinctorum

Abstract

Dedifferentiation was monitored in Rubia tinctorum L. leaves over a 14-d period after callus induction using transmission electron microscope (TEM), high performance liquid chromatography (HPLC), spectroscopy and thin layer chromatography (TLC). Photosynthetic pigment loss of leaves took 3 -5 d coinciding with the first period of anthraquinone accumulation. Callus cells were discernible in the region of the vascular bundles and wounded edges of leaves after 10 -14 d. Characteristic ultrastructural alterations were manifested in vacuolization, appearance of mitochondria, amount of smooth endoplasmatic reticulum and cytoplasm, caryolympha density of nuclei and cytoplasm content of cells. There were special events in the transfer cells: unequal divisions of dedifferentiated plastids and lytic activity in the cell wall. Our results show that mesophyll cells seem to be stopped at a particular level of dedifferentiation, while transfer cells embodied in veins of leaves pass through further alterations and lead to callus formation. Findings suggest that a sort of dedifferentiation drift manifests in the various cells of R. tinctorum leaves during callus induction and depending on their specialized status they achieve different levels of dedifferentiation. Approximately 4 weeks after callus induction, root growth has started from the young calli.

Histological and Ultrastructural Observation Reveals Significant Cellular Differences between Agrobacterium Transformed Embryogenic and Non‐embryogenic Calli of Cotton

“…The chloroplasts of non‐embryogenic callus were similar to chloroplasts of mesophyll cells. A similar phenomenon was observed in somatic embryogenesis of other plants (Wang et al 1998; Caredda et al 1999; Mikula et al 2007; Orban et al 2007).…”

“…Some research groups conducted light and electron microscopy to study structural and cellular changes involved during acquisition of embryogenic competence. These research reports provided detailed descriptions of the morphological and ultrastructure changes that characteristics of acquisition of embryogenic competence and embryoid initiation (Sunilkumar and Rathore 2001; Poljuha et al 2003; Moghaddam and Taha 2005; Namasivayam et al 2006; Mikula et al 2007; Orban et al 2007).…”

An efficient regeneration system of barley cultivars from leaf base segments

“…Young seedlings can be grown in vitro and used as donor plants for fast, frequent supply of explants (Chung et al 2007, Sujatha andKumar 2007). Leaf segments derived from seedlings are easily available and require a short time for culture (Haliloglu 2006, Orban et al 2007, Mingozzi and Morini 2009. They can serve as ideal target for genetic transformation (Gless et al 1998a).…”