Methyl Jasmonate Affects Photosynthesis Efficiency, Expression of HvTIP Genes and Nitrogen Homeostasis in Barley

Abstract

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 effect of methyl jasmonate on the growth parameters and photosynthesis efficiency of barley seedlings that had been exposed to different doses of MeJA (15–1000 µM × 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 µM 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 efficiency. 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.

Genetic diversity and evolutionary patterns of Taraxacum kok‐saghyz Rodin

“…Additionally, mutations, recombination, the number of active alleles, genetic drift, and genetic structure also could influence the amount of variation within a population (Ambreen et al, 2018 (Ahan et al, 2017) and the population may have expanded after the temporary bottleneck. The admixture among individuals was also reported in other crops such as Nigella sativa L. (Golkara & Nourbakhshb, 2019), safflower (Ambreen et al, 2018), and Simrouba glauca (Kumar & Agrawal, 2017 (Hu et al, 2017;Kurowska et al, 2020;Wingler et al, 2020). Therefore, the genetic diversity and selection pressures may enable the TKS to adapt to a variety of environmental conditions in different geographical regions.…”

Aquaporins in Cereals—Important Players in Maintaining Cell Homeostasis under Abiotic Stress

“…Photosynthesis in plants is regulated by AQPs through their effect on CO 2 transport in the membranes of the chloroplast and thylakoid [ 69 , 70 , 71 ]. Another example is that by facilitating the urea and NH 4 + /NH 3 uptake, the AQPs ensure the N homeostasis [ 71 , 72 ]. The enabling of H 2 O 2 diffusion by AQPs seems to be very important during the stress response when the reactive oxygen species are produced, while on the other hand the transport of this signalling molecule could have important functions in plant development and the regulation of a wide range of physiological processes [ 73 ].…”

TIP Aquaporins in Plants: Role in Abiotic Stress Tolerance

“…Methyl jasmonate treatment caused a decrease in the nitrogen content in barley leaves, which was associated with an increased expression of the four tonoplast aquaporin genes (HvTIP1;2, HvTIP2;2, HvTIP4;1 and HvTIP4;2), which are predicted to transport the nitrogen compounds from the vacuole to the cytosol. The up-regulation of the nitrogen-transporting HvTIPs may lead to a vacuolar unloading of ammonia and urea, which could both be remobilised when the nitrogen content in barley leaves decreases [109]. In barley, the changes in the expression of all of the investigated HvTIPs in response to MeJA treatment were associated with the presence of the cis-regulatory elements in their promotor regions, which are recognised by the jasmonate-related transcription factors [109].…”

“…The up-regulation of the nitrogen-transporting HvTIPs may lead to a vacuolar unloading of ammonia and urea, which could both be remobilised when the nitrogen content in barley leaves decreases [109]. In barley, the changes in the expression of all of the investigated HvTIPs in response to MeJA treatment were associated with the presence of the cis-regulatory elements in their promotor regions, which are recognised by the jasmonate-related transcription factors [109]. Other types of elements that possibly participate in the response to phytohormones in the HvTIP promotor regions such as abscisic acid (ABA), gibberellins (GA) and auxin were also identified [89].…”