Dissecting the Molecular Function of Triticum aestivum STI Family Members Under Heat Stress

Abstract

STI/HOP functions as a co-chaperone of HSP90 and HSP70 whose molecular function has largely been being restricted as an adaptor protein. However, its role in thermotolerance is not well explored. In this article, we have identified six members of the TaSTI family, which were named according to their distribution on group 2 and group 6 chromosomes. Interestingly, TaSTI-2 members were found to express higher as compared to TaSTI-6 members under heat stress conditions, with TaSTI-2A being one of the most heat-responsive member. Consistent with this, the heterologous expression of TaSTI-2A in Arabidopsis resulted in enhanced basal as well as acquired thermotolerance as revealed by the higher yield of the plants under stress conditions. Similarly in the case of rice, TaSTI-2A transgenics exhibited enhanced thermal tolerance. Moreover, we demonstrate that TaSTI-2A interacts with TaHSP90 not only in the nucleus but also in the ER and Golgi bodies, which has not been shown till now. Additionally, TaHSP70 was also found to interact with TaSTI-6D specifically in the cytosol. Thus, these data together suggested that the TaSTI family members might play different roles under heat stress conditions in order to fine-tune the heat stress response in plants.

HOP, a Co-chaperone Involved in Response to Stress in Plants

“…On the other hand, an unusual high accumulation of insoluble and ubiquitinated proteins is observed in the hop1 hop2 hop3 triple mutant at high temperature, which suggests that HOPs play a main role in the quality control (QC) of the cytoplasmic proteins under heat (Fernandez-Bautista et al, 2018). In adition, quite recently, a functional role of TaSTI-2A in thermotolerance acquisition has been also reported in wheat (Meena et al, 2020).…”

“…In some species, HOP is encoded by multi-gene families. In this sense, analysis of different databases retrieves only one HOP member in barley and tomato; two members are identified in rapeseed and soybean, three members are present in Arabidopsis and maize, and six members have been recently identified in Triticum aestivum (Table 1 and Meena et al, 2020).…”

Overexpression of HVA1 Enhances Drought and Heat Stress Tolerance in Triticum aestivum Doubled Haploid Plants

“…For drought stress treatment, the seeds were germinated on a cotton bed in a growth chamber maintained at a 24/20 °C daily temperature under a daily cycle of 16 h light/8 h dark photoperiod having 200–300 μmol m −2 s −1 of light intensity. Ten-day-old seedlings were subjected to 200 mM mannitol for 24 h for drought stress and then allowed to recover [ 31 , 32 ]. The plants were photographed after 2 days of recovery.…”

“…The photographs of the leaf segments were taken after the 4 days of incubation. For giving drought stress at the vegetative and reproductive stage, potted plants (both transgenic and the WT) at Zadok stage Z30 and at the anthesis stage, i.e., Zadok stage 60–64, were selected and the plants were supplemented with 200 mM mannitol solution for 24 h [ 31 ]. After the drought stress, the leaf and the spike tissue were harvested and frozen in liquid nitrogen immediately for the RNA-seq analysis.…”

“…After the drought stress, the leaf and the spike tissue were harvested and frozen in liquid nitrogen immediately for the RNA-seq analysis. Similarly, for heat stress treatments at vegetative and reproductive stages, plants at Zadok stage 30 and Zadok stage 60 were subjected to 42 °C for 2 h and 4 h, respectively [ 31 , 34 ]. The leaf and the spike tissue were harvested immediately after stress for the RNA-seq analysis.…”