A comparative histological study between normal and fasciated shoots of Prunus avium generated in vitro

Abstract

A combination of Murashige and Skoog's medium and N 6 -benzyladenine (BA) at various concentrations (0, 0.1, 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 mg l )1 ) was supplied to shoot tips from root cuttings of a 50-yearold wild-cherry tree (Prunus avium). The concentration of BA in the growing medium was a determining factor with respect to the number of proliferated shoots per explant in vitro. Normal and fasciated shoots were generated when BA was present at 0.5, 0.75, 1.0 and 1.25 mg l )1 in the medium and the mean numbers of normal shoots per explant were 3.63, 5.37, 8.93 and 7.30 respectively, and those of the fasciated shoots per explant were 0.03, 0.1, 0.47 and 0.4 respectively. Anatomical analysis by confocal microscopy of sections of paraffin-embedded specimens revealed that the cell structure and organization of the cortex and vascular cylinder in the fasciated shoots was similar to that in normal shoots. However, the cross-sectional area of stem of the fasciations was apparently greater than that of the normal shoots. In particular, the volume of vascular tissues, of pith and of some individual parenchyma cells in the cortex and pith was apparently greater in fasciated shoots than in normal shoots. Increases in cytokinesis and morphogenetic activity, such as the development of callus-like regions and the formation of adventitious shoots, were observed in the cortex and pith throughout the fasciations. The fasciated shoots had numerous buds and initiating new shoots at their apices while normal shoots had a single dominant axial bud.

Infection byRhodococcus fasciansmaintains cotyledons as a sink tissue for the pathogen

“…Sections were counter-stained with 0Á5 % (v/v) Eosin Y (Sigma) in 100 % ethanol. Sections were then treated with 1:1 xylene:absolute ethanol, followed by 100 % xylene at room temperature for 3 min, mounted in Eukitt and dried in a 37 C oven for a minimum of 2 d (Kitin et al, 2005). The stained sections were viewed using a Zeiss Axio Imager M1 compound microscope with brightfield (BF) and differential interference contrast (DIC) optics/lighting capabilities.…”

Molecular identification of phytoplasmas in fasciated cacti and succulent species and associated hormonal perturbation

“…Previous reports demonstrated that exogenously applied cytokinins induced fasciation in Kalanchoe blossfeldiana (Varga et al 1988), B. pendula (Iliev 1996), Mammillaria elongata (Papafotiou et al 2001), and P. avium (Kitin et al 2005). Also, it has been reported that fasciation in cotton is conditioned by GA 3 and genotype (Nadjimov et al 1999).…”

“…Similarly, fasciation in pea is characterized by abnormal enlargement of the stem apical meristem leading to distortions in shoot structure (Sinjushin & Gostimsky 2006. Fasciated shoots of Betula pendula induced in vitro as well as Prunus avium and Fraxinus excelsior formed flattened stems with densely arranged lanceolate leaves that were dramatically increased in size (Kitin et al 2005;Mitras et al 2009;Iliev & Kitin 2011). …”

Origin, morphology, and anatomy of fasciation in plants cultured in vivo and in vitro

“…Enlarged SAMs were observed in tissue culture in the presence of high cytokinin concentrations (Brossard 1976;Iliev and Tomita 2003;Iliev et al , 2011Kitin et al 2005). After cytokinin treatments, calli surrounded with continuous meristematic bands that formed enlarged SAMs were observed.…”