Special seminar: doc. Mgr. Markéta Šámalová, Ph.D.

Čas	14.05.2024 od 15:00 do 16:30
Přiložený soubor:	2024_LS_seminar_Samalova
Přidat událost do kalendáře	Google vKalendář (Windows, Linux) iCal (Mac OS X)

doc. Mgr. Markéta Šámalová, Ph.D.

(Masaryk University, Faculty of Science - Section of Experimental Plant Biology)

Připojte se online: meet.google.com/qhf-etyu-sna

Changes in cell wall (CW) mechanics drive plant growth and development. Expansins were
originally discovered as pH-responsive agents facilitating cell expansion by mediating CW
loosening in plants (McQueen-Mason et al., 1992). In our recent work, we determined
spatiotemporal expression and localization of hormone-regulated EXPAs in Arabidopsis roots
and assessed their role in controlling the biomechanical properties of CW using Brillouin
Light Scattering (BLS) spectroscopy (Keshmiri et al., 2024). Overexpression of EXPA1 in a
dexamethasone-controlled system resulted in stiffer root CWs determined by a higher
Brillouin frequency shift as well as an apparent Young`s modulus measured by atomic force
microscopy (AFM) as early as 3 h after its upregulation (Samalova et al., 2024).
The EXPA1-overexpressed plants had an unexpected phenotype with shorter seedling roots
and smaller, more compact adults with numerous shoots and rounded leaves. Genome-wide
transcriptome analysis revealed rapid changes in the transcription of other genes associated
with CW modification and remodelling. Our preliminary data show that the plants are more
resistant to drought stress and pathogen attack. This is consistent with the recent identification
of expansins as a main enriched gene family in root core stress genes, highlighting the
importance of the tissue-specific expansins in stress signalling (Sanchez-Munoz et al., 2024).
However, we are curious to investigate what is behind the unexpected root phenotype and
therefore we overexpressed EXPA1 in selected cell types. To ensure that the expansins were
in a low pH environment, we activated the proton pumps by overexpressing
AHA295:mTurquoise2 fusion in the same pattern as EXPA1. Our results lead to differential
growth responses and highlight the importance of mechanisms guiding tissue-specific CW
microenvironment in coordinating plant growth and rise potential constrains for the acid
growth theory in Arabidopsis roots.

MS received funding from the Grant Agency of the Czech Republic project No. 22-17501S.