Identified a family of cochaperones involved in plant thermotolerance to high temperatures

Researchers from the CBGP (UPM-INIA) from the group "Regulation of translation under stress conditions in plants" have revealed the key role of HOP proteins in the establishment of long-term acquired thermotolerance in plants.

HOP is a family of proteins that interacts with the chaperones HSP70 and HSP90. Members of the HSP70 and HSP90 families play an important role in different developmental processes and in the response to different environmental conditions, specifically to high temperatures. However, it was largely unknown to date if the cochaperones HOP are involved in the response to this stress and their molecular role in this process.In this work, the authors show that HOP family plays an essential role in the process that allows plants to tolerate extreme temperatures for several days after a process of acclimation.

In Arabidopsis, the HOP family consists of three members: HOP1, HOP2 and HOP3, which have a differential expression pattern in response to high temperatures. HOP1 and HOP2 are constitutive while HOP3 is induced by heat. However, despite the strong induction of HOP3 during this stress, the three members of the family participate in the establishment of plant memory to high temperatures. The data show that HOP proteins are mainly located in the cytoplasm under control conditions, whereas this subcellular localization changes drastically under stress, partially shuttling form the cytoplasm to the nucleus and to stress granules (cytoplasmic protein aggregates that form during heat shock conditions) .Consistent with their nuclear location, these proteins play an essential role in the correct establishment of gene expression during the process of acclimation of plants at high temperatures. In addition, the provided data demonstrate that these proteins participate in the quality control in response to heat, a process that ensures the correct folding of proteins (and therefore their possible functionality) or their degradation in the case that the proteins have not reached a correct structure.

Image: HOP proteins play a major role in long term-acquired thermotolerance (LAT) in plants. Growth of the hop1 hop2 hop3 triple mutant, the hsfa2 mutant (a mutant with a well-known hypersensitive to heat stress, included as a positive control) and Col-0 (the wild-type genotype) under control (A) and under LAT conditions (B).

Original Paper:

Fernández‐Bautista, N; Fernández‐Calvino, L; Muñoz, A; Toribio, R; Mock, HP; Castellano, MM. "HOP family plays a major role in long term acquired thermotolerance in Arabidopsis". Plant, Cell & Environment. DOI: 10.1111/pce.13326".