Effects of IAA, BA and light conditions on differentiation of pepper callus in vitro
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The aim of the presented research was to determine the changes of morphology (texture, friability, coloration), and to extend the cytodifferentiation (tracheary element differentiation), as well as growth potential of pepper (Capsicum annuum L.) callus in response to growth regulators (IAA, BA) and various light conditions. Callus was induced under l6-h photoperiod from embedded, mature embryos which were placed on MS medium supplemented with 1 mg/l 2,4-D. After induction, callus was transferred on MS medium with IAA and BA (0.02, 0.1, 0.5 mg/l), added alone and in combinations. The cultures were incubated both in 16-h photoperiod and darkness for 4 weeks. Auxin stimulated the formation of smooth callus surface, while cytokinin used alone and with various concentration of auxin showed the tendency to produce nodular callus. Soft and friable calli occurred in the presence of IAA, whereas BA frequently stimulated the compact one. Light effected the reduction of cells? cohesion of calli, regarding auxin medium and the increase of cells? cohesion in the case of the highest concentration of IAA with BA combinations. Green coloration associated with chloroplast differentiation was observed mainly in callus from medium containing cytokinin alone at higher concentrations and cytokinin with auxin also at higher concentrations. The largest number of explants with xylogenesis (100%) was noted at the highest concentration of BA added alone to medium and with combinations of IAA. Three types of the tracheary element arrangements (clusters of izodiametric cells, strands and whirls of elongated cells), were observed. The most effective callus growth occurred in the darkness and the increase of callus fresh weight was about twice bigger than under the light. The best combination of PGRs in callus growth appeared to be 0.1 mg/l IAA + 0.02 mg/l BA.
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A. Gatz, Katedra Fizjologii Roslin, Akademia Techniczno-Rolnicza, ul. Bernardynska 6, 85-029 Bydgoszcz, Poland