Effect of cytokinins on in vitro development of autotrophism and acclimatization of Annona glabra L.

Abstract

The role of cytokinins in the differentiation of the photosynthetic apparatus in micropropagated plants and their effect on the plant's ability to transition from a heterotrophic to an autotrophic condition during acclimatization was investigated. Annona glabra L. shoots were cultured on woody plant medium supplemented with sucrose and different cytokinins to evaluate leaf tissue for chloroplast development, chloroplast numbers, photosynthetic pigmentation, total photosynthetic potential, and soluble sugar content. Plants were transferred to the rooting medium in the presence or absence of sucrose and then acclimatized. Kinetin and benzyladenine (BAP) stimulated chloroplast differentiation. Inclusion of zeatin in the medium induced the formation of greater numbers of chloroplasts in the leaves, while plants cultivated in the presence of only kinetin and BAP demonstrated greater chlorophyll a and carotenoid content. The use of kinetin and BAP during in vitro culture promoted accumulation of dry matter during the acclimatization phase, especially in plants rooted under autotrophic conditions (without sucrose). Kinetin and BAP promoted development of more leaf area and greater plant survival rates in plant acclimatization on both autotrophic and heterotrophic media. The inhibitory effects of thidiazuron on the differentiation of chloroplasts, accumulation of chlorophyll a, and photosynthetic potential were examined.

Effects of cytokinins on in vitro mineral accumulation and bud development in Annona glabra L.

“…Many attempts have been made to cultivate (Zobayed et al, 2002;Nagori & Purohit, 2004) wild Annonaceae species (Santana et al, 2003;Oliveira et al, 2007Oliveira et al, , 2008Santana et al, 2008a,b) through micropropagation, but low levels of explant multiplication, slow shoots growth rates, and elevated explant mortality during acclimatization have contributed to the limited commercial success of this technique.…”

Efficient regeneration and Agrobacterium-mediated transformation protocol for recalcitrant indica rice (Oryza sativa L.).

“…In in-vitro shoot cultures of Annona gabra L., KIN and BAP were found to increase the shoots' chlorophyll content with KIN being reported to increase more than 30% of chlorophyll a and b. However, shoots cultured in TDZ media showed diminished chlorophyll content with irregular shapes and sizes of chloroplasts and a reduction in thylakoid membranes thereby causing lower photosynthetic activity than shoots produced in KIN and BAP (Oliveira et al, 2008). These findings were in agreement with this study in which KIN and BAP produced shoots with significantly higher total chlorophyll content whereas shoots produced in TDZ contained the least chlorophyll content.…”

“…Cytokinin was also reported to activate the synthesis of chlorophyll pigments and photosynthetic apparatus (Kulaeva et al, 2002;Oliveira et al, 2008). In in-vitro shoot cultures of Annona gabra L., KIN and BAP were found to increase the shoots' chlorophyll content with KIN being reported to increase more than 30% of chlorophyll a and b.…”

Rooting affects the photosystem II activity: in vitro and ex vitro studies on energy hybrid sorrel

“…Reduced leaf photosynthetic activity as a result of the poor development of the photosynthetic apparatus, inadequate gas exchange, stomata deformation and suppressed Rubisco activity has been revealed to limit successful in vitro to ex vitro transfer (Zenkteler and Borkowska 2002;Apóstolo et al 2005;Joshi et al 2006;de Oliveira et al 2008 and the literature therein). High mortality during acclimation to ex vitro conditions is mainly associated with the low ability of plantlets to regulate water loss as the result of anatomical abnormalities that had developed in vitro such as increased stomatal density (Joshi et al 2006) or root system damage during transfer from in vitro to ex vitro conditions.…”