Yukhno Yu.
V.N. Karazin Kharkiv National University, Kharkiv, Ukraine
Zhmurko V.
Doctor of Biological Sciences, Professor, V.N. Karazin Kharkiv National
University, Kharkiv, Ukraine
EFFECTS OF PHOTOPERIOD AND MATURITY GENES ON PLANT
HORMONE BALANCE IN THE LEAVES AND SHOOT APICAL
MERISTEMS IN SOYBEAN ISOGENIC LINES
Introduction. Plant growth and development are tightly controlled by sunlight
that governs trophic processes and light-dependent plant development in general as
well as the transition to flowering in particular (Amasino, 2010, Andrés et al, 2012,
Blümel et al., 2015). Cell differentiation of the shoot apical meristem is initiated by
environmental and endogenous cues, which include photoperiod (i.e., day length),
vernalization (exposure to a long period of cold), plant hormones etc. (Amasino, 2010,
Burgarella et al., 2016, Kazan et al, 2016, Reeveset al, 2001, Sun et al., 2014).
Moreover, plant hormones perform essential functions via triggering multiple signaling
networks, which transmit both external and internal cues and convert them into plant
response reactions (e.g. morphogenetic processes) (Santner et al., 2009; Wolters et al.,
2009). Modulation of plant hormones is reported to be primarily influenced by the
interaction and certain ratio of such environmental factors as light (quality of light and
photoperiod) and temperature (vernalization). Therefore, flowering time may be
determined by the effect of the plant hormone modulation. Gibberellins and cytokinins
are best studied to affect the transition to flowering. Gibberellins are shown to be “a
mobile floral signal” in such long-day plants as darnel (Lolium temulentum) and
Arabidopsis thaliana (King et al, 2001, Kohli et al, 2013). They are conveyed to the
shoot apical meristems (SAM) and induce the LFY (LEAFY) gene transcription, the
main function of which is a positive regulation of the floral homeotic group of genes
accordingly controlling floral meristem identity (Conti L., 2017). Cytokinins are
thought to have “florigen”-like activity due to increase the content of isopentyladenine
in long-day (LD) plants during inductive conditions. They induce TSF (TWIN SISTER
OF FT) and SOC1 (SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1)
transcription thereby activating the LFY gene expression (D’Aloila et al., 2011).
However, these plant hormone effects have been investigated mostly in LD plants
and not yet in SD plants (e.g. soybean). Not having their own direct signaling pathways
controlling the flowering initiation other plant hormones play an important role in this
process too. Auxin accumulation in Arabidopsis was shown to be necessary for a
vascular bundle formation under floral meristems and to precede the LFY gene
- 71 -