Proceedings Volume 2010 (format .pdf) - SimpBTH

GA 3 plays an important role in spinach plant regeneration. From the earliestreport (Nešković and Radojević 1973) to the modern days authors empasized itsindispensability (Al-Khayri et al. 1991a, 1991b, 1991c, 1992; Molving and Rose1994; Xiao and Branchard 1995; Knoll et al. 1997; Komai et al. 1996; Ishizaki etal. 2001). Ishizaki et al. (2001) pointed out that some highly responsive spinachlines did not regenerate in the abscence of GA 3 , and that GA 3 increased theregenerative capacity of all lines in a dose response manner. All these findings maybe in a correlation with fact that some stages in biosynthetic pathways ofgibberellins were controlled by photoperiod. Biosynthesis of ent-kauren, firststabile precursor of gibberellins, was enhanced in LD condition (Zeevaart andGage 1993), as well as oxidation of GA 53 →GA 44 and GA 19 → GA 20 (Gilmour et al.1986). Wu et al. (1996) demonstrated enhanced expression of gene coding forGA 20 -oxidase in spinach in LD. So, higher regeneration response of explants in LDcould be explained by higher level of endogenous gibberellins, probably differentof GA 3. GA 1 , whose level is higher in LD than in SD in spinach (Wu et al., 1996) isactive per se (Zeevaart et al. 1993) and it may influence the process ofregeneration.4. CONCLUSIONSWe indubitably demonstrated LD-stimulation of the process of somaticembryogenesis from root sections of spinach and confirmed very high individualvariability of regeneration response. This study is a valuable contribution to theefficiency of spinach regeneration, usable in breeding programs for developingnew varieties. On the other hand, as gibberellin biosynthetic pathway was readilystudied in spinach and the gene sequences, their expression and enzymes activitiesare well known, this system may be valuable in highlighting the role of gibberellinsin the process of regeneration in spinach.ACKNOWLEDGEMENTS This work was supported by the Ministry of Science andTechnological Development of the Republic of Serbia, Contract No. 143026B.REFERENCES1. Al-Khayri, J. M., Huang, F. H., Morelock, T. E., Busharar, T. A., Gbur, E. E. (1991a): Genotypedependentresponse of spinach cultivars to in vitro callus induction and plant regeneration. Plant Sci.Vol. 78, 1: 121-126.2. Al-Khayri, J. M., Huang, F. H., Morelock, T. E. (1991b): Regeneration of spinach from leaf callus.Hort. Sci. Vol. 26, 7: 913-914.3. Al-Khayri, J. M., Huang, F. H., Morelock, T. E. (1991c): Micropropagation of spinach. ArkansasFarm Res. Vol. 40, 1: 7.4. Al-Khayri, J. M., Huang, F. H., Morelock, T. E., Busharar, T. A. (1992): Stimulation of shootregeneration in spinach callus by gibberellic acid. Hort. Sci. Vol. 27, 9: 1046.5. Ćulafić, Lj. (1973): Induction of flowering of isolated Spinacia oleracea L. buds in sterile culture.Bull. Inst. Jard. Bot. Univ. Belgrade. Vol. 7, 1-4: 53-56.59