Drought stress and re-watering affect the abundance of TIP aquaporin transcripts in barley

PLoS One. 2019 Dec 17;14(12):e0226423. doi: 10.1371/journal.pone.0226423. eCollection 2019.

Abstract

Tonoplast Intrinsic Proteins (TIP) are plant aquaporins that are primarily localized in the tonoplast and play a role in the bidirectional flux of water and other substrates across a membrane. In barley, eleven members of the HvTIP gene subfamily have been identified. Here, we describe the transcription profile of the HvTIP genes in the leaves of barley seedlings being grown under optimal moisture conditions, drought stress and a re-watering phase. The applied drought stress caused a 55% decrease in the relative water content (RWC) in seedlings, while re-watering increased the RWC to 90% of the control. Our analysis showed that all HvTIP genes, except HvTIP3;2, HvTIP4;3 and HvTIP5.1, were expressed in leaves of ten-day-old barley seedlings under optimal water conditions with the transcripts of HvTIP2;3, HvTIP1;2 and HvTIP1;1 being the most abundant. We showed, for the first time in barley, a significant variation in the transcriptional activity between the analysed genes under drought stress. After drought treatment, five HvTIP genes, which are engaged in water transport, were down-regulated to varying degrees, while two, HvTIP3;1 and HvTIP4;1, were up-regulated. The HvTIP3;1 isoform, which is postulated as transporting hydrogen peroxide, expressed the highest increase of activity (ca. 5000x) under drought stress, thus indicating its importance in the response to this stress. Re-hydration caused the return of the expression of many genes to the level that was observed under optimal moisture conditions or, at least, a change in this direction Additionally, we examined the promotor regions of HvTIP and detected the presence of the cis-regulatory elements that are connected with the hormone and stress responses in all of the genes. Overall, our results suggest that 7 of 11 studied HvTIP (HvTIP1;1, HvTIP1;2, HvTIP2;1, HvTIP2;2, HvTIP2;3, HvTIP3;1, HvTIP4;1) have an important function during the adaptation of barley to drought stress conditions. We discuss the identified drought-responsive HvTIP in terms of their function in the adaptation of barley to this stress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Aquaporins / chemistry
  • Aquaporins / genetics*
  • Droughts*
  • Gene Expression Regulation, Plant / drug effects
  • Hordeum / drug effects
  • Hordeum / genetics*
  • Hordeum / metabolism
  • Hordeum / physiology*
  • Plant Growth Regulators / metabolism
  • Promoter Regions, Genetic / genetics
  • RNA, Messenger / genetics
  • Stress, Physiological / drug effects
  • Stress, Physiological / genetics*
  • Water / pharmacology*

Substances

  • Aquaporins
  • Plant Growth Regulators
  • RNA, Messenger
  • Water

Grants and funding

This research was funded by National Science Centre, Poland, project SONATA 2015/19/D/NZ1/03441 to MK. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.