Citokininska homeostaza i ekspresija gena uključenih u kontrolu ćelijskog ciklusa tokom procesa regeneracije kelerabe (Brassica oleracea L. var. gongylodes) in vitro
Cytokinin homeostasis and expression of the genes involved in cell cycle control during kohlrabi (Brassica oleracea L. var. gongylodes) regeneration in vitro
Doctoral thesis (Published version)
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vitro plant regeneration is under control of plant growth regulators (PGRs), especiallycytokinins and auxins. Exogenously applied PGRs can affect the homeostasis ofendogenous plant hormones by influencing their biosynthesis and distribution,subsequently altering in vitro development. Intensive cell divisions represent the basisof in vitro plant regeneration, and they are controlled by complexes of cyclins andcyclin-dependent kinases. The activity of these complexes during cell cycle and organdevelopment is affected by plant hormones. Respecting this, the aims of this study weredeveloping efficient protocols for in vitro regeneration of kohlrabi (Brassica oleraceaL. var. gongylodes) with an emphasis on identification and quantification of differentgroups of endogenous cytokinins and indole-3-acetic acid (IAA) in explant tissue withrespective regenerated shoots, as well as analyzing expression of genes encoding cyclinsand and cyclin-dependent kinases during de novo shoot organogenesis. Efficient systemfor repetitive somatic embryogenesis (SE) was developed for kohlrabi cv. ViennaPurple (VP) using immature zygotic embryos. The highest frequency of SE wasobtained from immature zygotic embryos at the early cotyledonary stage grown onPGR-free medium.Successful induction of de novo shoot organogenesis in kohlrabi cv VP and cv. ViennaWhite (VW) was achived using hypocotyl explants and intact seedlings, cultivated onmedia supplemented with single cytokinin (CK): 6-benzylaminopurine (BAP),thidiazuron (TDZ), trans-zeatin (transZ) or cis-zeatin (cisZ). Higher frequency of shootregeneration as well as viability of regenerated shoots was detected for intact seedlings,with BAP and TDZ being the most efficient in de novo organogenesis induction.Quantification of endogenous cytokinin and IAA contents in both hypocotyl explantsand seedlings with regenerated shoots (HRSs and SRSs, respectively) suggested that theobserved differences in organogenic response between these two types of starting plantmaterial were related to their cytokinin and IAA contents. The level of total CKs washigher in HRSs, while SRSs displayed a higher IAA/bioactive CKs ratio...
Keywords:Kohlrabi (Brassica oleracea L. var. gongylodes); Immature zygoticembryos; Somatic embryogenesis; Hypocotyl; Seedling; De novo organogenesis; Cytokinins; Cell cycle genes; Cyclins; Cyclin-dependent kinases
Source:University of Belgrade, Faculty of Biology, 2015, 1-171