Role of ethylene biosynthesis and signaling in elevated CO2-induced heat stress response in tomato

This article unveiled that ethylene biosynthesis and signaling play a critical role in heat stress response of tomato plants under elevated CO_2. Plant responses to elevated CO₂ and heat stress are tightly regulated by an intricate network of phytohormones. Plants accumulate ethylene (ET), the smallest hormone, in response to heat stress; however, the role of ET and its signaling in elevated CO₂-induced heat stress response remains largely unknown. In this study, we found that transcript levels of multiple genes relating to ET synthesis, signaling, and heat shock proteins (HSPs) were induced by elevated CO₂ (800 μmol mol^-1) compared to ambient CO₂ (400 μmol mol^-1) in tomato leaves under controlled temperature conditions (25 °C). Elevated CO₂-induced responses to heat stress (42 °C) were closely associated with increased ET production and HSP70 expression at both transcript and protein levels. Pretreatment with an antagonist of ET, 1-methylcyclopropene that inhibits ET-dependent responses, abolished elevated CO₂-induced stress response without affecting the ET production rate. In addition, silencing of ethylene response factor 1 (ERF1) compromised elevated CO₂-induced responses to heat stress, which was associated with the concomitant reduction in the transcript of heat shock factor A2, HSP70 and HSP90, indicating that ERF1 is required for elevated CO₂-induced responses to heat. All these results provide convincing evidence on the importance of ET biosynthesis and signaling in elevated CO₂-induced heat stress response in tomato plants. Thus, the study advances our understanding of the mechanisms of elevated CO₂-induced stress response and may potentially be useful for breeding heat-tolerant tomatoes in the era of climate change.

Basal and dynamics mRNA expression of muscular HSP108, HSP90, HSF-1 and HSF-2 in thermally manipulated broilers during embryogenesis

Background

Limited data are available about the kinetics of mRNA expressions of Heat shock proteins (HSPs) and heat shock factors (HSFs) in the thermally manipulated (TM) broiler chicks during acute heat stress. Therefore, this study aimed to investigate effects of thermal manipulation (TM) of broiler chicken during embryonic days (ED) 12–18 on the basal and dynamics mRNA expression of heat shock proteins (HSP108 and HSP90) and heat shock factors (HSF-1 and HSF-2) in the muscle tissue during late embryogenesis, first week of life and during heat stress (HS) on post-hatch days 14 and 28. One thousand and five hundred fertile Ross 315 broiler eggs were randomly allocated to five groups: control group (37.8 °C), TM₁ (38.5 °C for 18 h), TM₂ (39 °C for 18 h), TM₃ (39.5 °C for 18 h) and TM₄ (40 °C for 18 h). Chicks from each treatment group were then randomly sub-divided into two further treatment groups, naïve and thermal challenged (TC). On post-hatch days 14 and 28, thirty chicks from each TC group were subjected to heat stress (41 °C for 6 h), while naïve chicks of each group (n = 30) were kept under regular conditions. The response of chicks to heat stress was investigated by evaluating the change in mRNA expressions of HSP108, HSP90, HSF-1 and HSF-2 in muscle tissue after 1, 3 and 5 h of heat stress.

Results

When compared to the control group, TM resulted in significant increases in the basal mRNA expression of HSPs and HSFs during embryogenesis and altered their dynamic expressions in the muscle tissue after heat stress on post-hatch days 14 and 28.

Conclusion

the current study indicated short- and long-term enhancement of HSPs and HSFs gene expression which was associated with acquisition of improved thermotolerance in thermally manipulated chicks.