The Seed Development Factors TT2 and MYB5 Regulate Heat Stress Response in Arabidopsis

HEAT SHOCK FACTOR A2 (HSFA2) is a regulator of multiple environmental stress responses required for stress acclimation. The FLOCAD’s team from IPS2 (https://ips2.u-psud.fr/en/research/dgg-department-developmental-genomics-and-genetics/flocad-developpement-floral-et-determinisme-du-sexe.html), in collaboration with the teams of Richard G. H. Immink (Wageningen University), Loic Lepiniec (IJPB, INRAE Versailles) and Heribert Hirt (University of Vienna) analyzed HSFA2 co-regulated genes and identified 43 genes strongly co-regulated with HSFA2 during multiple stresses. A motif enrichment analysis revealed an over-representation of the site II element (SIIE) in the promoters of these genes. In a yeast 1-hybrid screen with the SIIE, we identified the closely related R2R3-MYB transcription factors TT2 and MYB5. We found overexpression of MYB5 or TT2 rendered plants heat stress tolerant. In contrast, tt2, myb5, and tt2/myb5 loss of function mutants showed heat stress hypersensitivity.

Transient expression assays confirmed that MYB5 and TT2 can regulate the HSFA2 promoter together with the other members of the MBW complex, TT8 and TRANSPARENT TESTA GLABRA 1 (TTG1) and that the SIIE was involved in this regulation. A transcriptomic analysis revealed that TT2/MYB5 target promoters are enriched in SIIE. Overall, we report a new function for TT2 and MYB5 in stress resistance and a role in SIIE-mediated HSFA2 regulation.

This work was supported by Gautier Semences SA and the ANRT (CIFR2012/1125) and by the Labex Saclay Plant Sciences-SPS (ANR-10-LABX-0040-SPS) and has been published in the Genes journal.

Reference:

Pierre Jacob, Gwilherm Brisou, Marion Dalmais, Johanne Thévenin, Froukje van der Wal, David Latrasse, Ravi Suresh Devani, Benhamed Moussa, DUBREUCQ Bertrand, Adnane Boualem, Loic Lepiniec, Richard G.H. G. H. Immink, Heribert Hirt, Abdelhafid Bendahmane. The Seed Development Factors TT2 and MYB5 Regulate Heat Stress Response in Arabidopsis. Genes, Volume 12, Issue 5, released on 24 May 2021.