A protective role of HSP90 chaperone in gamma-irradiated Arabidopsis thaliana seeds

Rocket Science: The Effect of Spaceflight on Germination Physiology, Ageing, and Transcriptome of Eruca sativa Seeds

“…Again, the lesser effect of ageing on expression of HSP90-1 and HSP90-2-like in space-flown seeds reflects the position (in the PCA, Figure 3A) of space-flown dry seeds as being between dry and CAAT seeds. Roles of HSPs in spaceflight responses ( Figure 5, [11,60,61]) are further supported by heat shock factor transcript expression patterns, including HSFA7a-like in Space seeds ( Figure 5) and HSFA2 [11].…”

“…For maize seeds abovẽ 100 Gy caused a reduction in the maximal germination percentage and also reduced plant growth [83]. No reduction in the maximum germination percentage was observed when dry Arabidopsis seeds were γ-irradiated with 100-1000 Gy, but DNA damage and seedling defects were observed at 100 Gy and increased in a dose-dependent manner [60]. Mixed results were obtained for seed storage in the long-duration-exposure facilities of satellites in LEO, resulting in reduced, equal, or improved germination and survival compared to seeds stored on Earth [1,5].…”

“…Stress response processes were also identified as being important in the CAAT and spaceflight-induced DEGs, including the GO terms 'response to heat' and 'protein folding'. Indeed, a number of heat shock proteins (HSPs) and chaperones [11,60,61] were found to have elevated expression in CAAT aged samples, and in space-flown samples, including HSP90-2-like, HSP90-1, class III HSP, JJJ1, and several DNAJ-related transcripts ( Figure 5) and other HSPs (Supplementary Data File). For example, HSP90-1 expression was increased by 53%, 74%, and 38% in CAAT treated Earth-WS, Earth, and Space seeds, respectively.…”

HSP90 buffers newly induced mutations in massively mutated plant lines

“…Lastly, our study design allowed us to address the controversy whether HSP90-dependent phenotypes are largely a consequence of de novo mutations arising in HSP90-reduced lines as recently argued (22). Although HSP90 inhibition increases the frequency of certain mutations (2,20,21,23,24,(43)(44)(45)(46)(47)(48), we find no evidence that the majority of HSP90-dependent phenotypes observed here arises due to HSP90-dependent de novo mutations. In sum, our results resolve the two remaining controversies surrounding the HSP90 capacitor hypothesis.…”

“…RNAi-C1 background is either that these plants were more deeply mutagenized than Col-0 plants or that fewer mutations were repaired. HSP90 chaperones proteins that function in DNA repair (50,51), and as HSP90 inhibition also increases the rate of certain mutations (2,(20)(21)(22)(23)(43)(44)(45)(46)(47)(48), even equivalent EMS treatments may produce more mutations in the HSP90 RNAi-C1 background. Alternatively, as predicted under the capacitor hypothesis (25,31,(52)(53)(54), some EMS-generated mutations may acquire greater penetrance when HSP90 is inhibited and therefore result in embryonic lethality.…”