Біологічні студії (Dec 2016)
Peculiarities of accumulation and localization of indole-3-acetic acid in organs of Salvinia natans (L.) All. sporophyte at the different phenological development phases
Abstract
Plants of heterosporous annual fern hydrophyte Salvinia natans L. were collected in ponds of the Desniansky district of Kyiv city during summer time beginning from June, 2015 at one-month interval. Biometric studies of the whole plant (clone) and some segments of floating and submerged fronds showed that changes in the sporophyte weight and length at the various phenological phases of development occurred mostly owing to newly formed organs (modules) while linear dimensions of some formed fronds remained practically unchanged. The weight and length of an individual submerged frond considerably exceeded those of floating one. At the steady-state growth phase (July) the weight of an individual submerged frond increased two times due to an intensive formation of multi-cellular filamentous hairs while the length remained almost unchanged. During the reproductive development (August-September) the sporophyte weight increased as a result of sporocarps formation. The pattern of IAA accumulation and localization in organs of the sporophyte S. natans was for the first time analyzed using HPLC. At the phase of a fern intensive growth (June), the total IAA content of floating and submerged fronds was shown to be similarly high and reached 182 ng/g of fresh weight. During an active overgrowth and pubescence of submerged fronds (July) the endogenous IAA content was 546.3 ng/g of fresh weight while the quantity of this hormone in floating fronds remained at the level of the previous phase. A considerable reduction of this hormone content in ageing floating and submerged fronds was observed following the sporogenesis beginning at the phase of sporocarp formation and spore ripening. At the stage of late sporogenesis in the beginning of vegetative organs dying phase (September), the total IAA content in sporocarps that contained mature spores was 193 ng/g of fresh weight. The free hormone form dominated at the stage of an active and steady-state growth of floating and submerged fronds. Conjugated IAA was localized mostly in submerged fronds in quantity which exceeded that of floating ones 4 and 36 times, respectively. Distribution of this hormone between floating and submerged fronds shows that during the steady-state growth phase IAA is localized in submerged fronds, while at the phase of vegetative organs dying – in sporocarps. Specific changes in accumulation and localization of endogenous IAA revealed the correlation between growth processes and distribution, and content of phytohormone free and conjugated forms in sporophyte vegetative and reproductive organs of S. natans water fern during its individual development.
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