Jasmonates modulate many growth and developmental processes and act as stress hormones
that play an important role in plant tolerance to biotic and abiotic stresses. Therefore, there is a
need to identify the genes that are regulated through the jasmonate signalling pathway. Aquaporins,
and among them the Tonoplast Intrinsic Proteins (TIPs), form the channels in cell membranes that
are responsible for the precise regulation of the movement of water and other substrates between
cell compartments. We identified the cis-regulatory motifs for the methyl jasmonate (MeJA)-induced
genes in the promoter regions of all the HvTIP genes, which are active in barley seedlings, and thus we
hypothesised that the HvTIP expression could be a response to jasmonate signalling. In the presented
study, we determined the e ect of methyl jasmonate on the growth parameters and photosynthesis
e ciency of barley seedlings that had been exposed to di erent doses of MeJA (15–1000 M 120 h)
in a hydroponic solution. All of the applied MeJA concentrations caused a significant reduction of
barley seedling growth, which was most evident in the length of the first leaf sheath and dry leaf
weight. The observed decrease of the PSII parameters after the exposure to high doses of MeJA
(500 M or higher) was associated with the downregulation of HvPsbR gene encoding one of the
extrinsic proteins of the Oxygen Evolving Complex. The reduced expression of HvPsbR might lead
to the impairment of the OEC action, manifested by the occurrence of the K-band in an analysis of
fluorescence kinetics after MeJA treatment as well as reduced photosynthesis e ciency. Furthermore,
methyl jasmonate treatment caused a decrease in the nitrogen content in barley leaves, which was
associated with an increased expression the four tonoplast aquaporin genes (HvTIP1;2, HvTIP2;2,
HvTIP4;1 and HvTIP4;2) predicted to transport the nitrogen compounds from the vacuole to the
cytosol. The upregulation of the nitrogen-transporting HvTIPs might suggest their involvement in
the vacuolar unloading of ammonia and urea, which both could be remobilised when the nitrogen
content in the leaves decreases. Our research provides tips on physiological role of the individual TIP
subfamily members of aquaporins under methyl jasmonate action
