Growth correlations and rna synthesis in different parts of the shoot apical meristem ofChenopodium rubrunt L. induced to flowering

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Abstract
Uridine-3H incorporation and RNA concentration were investigated in different parts of the shoot apical meristem ofChenopodium rubrum using autoradiography and cytophotometry. A single inductive cycle was sufficient to bring about postinductive first events in the shoot apex but not for complete flower differentiation. The initial activation of RNA synthesis manifested itself in all zones of the apex. The first increase was more conspicuous in the peripheral than in the central zone. The indications of the first events in the apices after a single inductive cycle disappear prior to morphological reversal to the vegetative state. Induction by three short days led to rapid flower differentiation. The increase in RNA synthesis and concentration was most conspicuous in the central zone in this case. The ratio of RNA synthesis and content between bud and leaf primordia (B/L) also change in relation to photoperiodic induction. In vegetative plants the B/L ratio was low while after induction it increased. The shifts in activity of RNA synthesis observed in the shoot apical meristem are related to the changes in growth activity of the different parts of the apex. The growth ratios in the apices bear the character of growth correlations. The change in the growth correlations following photoperiodic induction together with the total activation of RNA synthesis are considered to represent one of the first events of the transition to the reproductive state. Inkorporace uridinu-3H a koncentrace RNK byla studována v různych cástech osniho apikálniho meristemuChenopodium rubrum L. s použitim metod autoradiografie a cytofotometrie. Indukce jednim krátkym dnem postacila pro vyvoláni prvnich postinduktivnich projevàů, nikoliv pro liplnou květni diferenciaci. Poáčáteáčni aktivace syntézy RNK se projevila ve vsech zonách vrcholu. Zpoáčátku byl vzestup v periferni zonáě větáěi než v centrálni zoně, o den později se poměr inkorporaee uridinu a koncentrace RNK obrátil. Pred morfologickym zvratem do vegetativni fáze prvni postinduktivni projevy ve vrcholech mizi. Indukce tfemi krátkymi dny míla za následek rychlou květni diferenciaci. Zvyseni syntézy RNK a koncentrace RNK bylo největsi v centrálni zone. Poměr v syntéze RNK a v obsahu RNK mezi pupenovymi a listovymi primordii (B/L) se rovněz měnil podle fotoperiodické indukce. U vegetativních rostlin byl poměr B/L nízký, po indukei vzdy stoupal. Nalezené pfesuny v aktivitě syntézy RNK v rámci osniho vrcholového meristemu maji vztah k změnám v růstové aktivitě různych cásti vrcholů. Růstové poměry ve vrcholech maji Charakter růstovych korelaci. Změna růstovych korelaci po fotoperiodické indukei je vedle celkové aktivace syntézy RNK povazována za jeden z prvnich projevů pfechodu do reproduktivni fáze.