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Introduction
Recent data indicates a significant increase of mean air temperature and a higher heat waves’
frequency (IPCC, 2021), which lead to detrimental effects on crop yield and products quality.
Consequently, it becomes a necessity to produce thermotolerant cultivars which implies to decipher
the mechanisms underlying heat stress tolerance. Moreover, it is proved that a first stress exposure
can impact on the magnitude of the effect of later exposures to stress as a consequence of the first
stress induced-information, followed by its storage and retrieval, namely stress memory (Crisp et al.
2016; Kinoshita and Seki 2017; Lamke and Baurle 2017). Stress memory can be (i) either beneficial as
the first stress exposure triggers a priming effect which alleviates the negative effects of subsequent
stresses or (ii) negative when the effects of successive stresses cumulate and amplified. This
phenomenon constitutes a promising approach to explore in the perspective to promote stress
tolerance in crops (Wang et al. 2017, Liu et al. 2023). Stress memory implies biochemical modifications,
hormone balance adjustments and epigenetic regulations such as post transcriptional modifications
(PTMs) of histones, which in turn modify gene expression (Liu et al. 2023). Therefore, stress memory,
either positive or negative, reflects specific -omic signatures that could be used to identify genes and
physiological functions that, arguably, play a critical role in memory acquisition, and consequently, in
stress acclimation (Lamke and Baurle 2017, Gallusci et al. 2023). Nevertheless, which scheme of stress
-in terms of pre-stress features - induces positive memory in plants remains blurred and further
research is needed.
Material and Methods
A greenhouse experiment in oilseed rape (ORS, cv. Aviso) was designed to further test the effects of
different heat stress sequences (from October 2023 until July 2024). Based on prior findings (Magno
et al. 2021 and Delamare et al. 2023) and literature-based evidence (e.g. Lamke and Baurle, 2017),
different durations of recovery phase (i.e. period between two stresses) were tested.
Pre-stress sequences (Figure 1) were designed to last ca. 140°Cd, in order to avoid any age effect,
afterwards, the plants were exposed to an intense heat stress (Figure 1). Leaves and pods will be
collected, and stored at -80°C for omics analyses. Furthermore, during the heat stress sequences,
chlorophyll fluorescence, NIRS reflectance, organ biomass and nitrogen content will be measured. At
seed physiological maturity, the agronomic traits (yield and yield components, seed nutritional and
germination qualities) will be measured.
Expected results
As observed in Magno et al. (2021), 5-day recovery in between the mild and the intense heat stress
did not lead to priming effects as most of the plant performances were lowered, thus reflecting
cumulative negative effects of both the mild and the intense stresses. Contrastingly, a gradual increase
prior to the intense heat stress (meaning no recovery phase) as tested in Delamare et al. (2023)
induced priming effects on yield and several seed quality criteria. Therefore, we conjecture that we
will find contrasting results on plants’ performances according to the three pre-stress modalities i.e.,
the EP being penalizing, while IP and LP being priming. Besides, significant changes in the metabolome
as well as a broad identification of transcripts, proteins and PTMs (Ding et al. 2012, Serrano et al. 2019,
Pratx et al. 2023) are expected.
Discussion
After the interpretation of the aforementioned expected results and the incorporation to the existed
literature, we aim at (i) identifying specific- omics signatures that reflect a positive memory (priming)
and (ii) decoding the mechanisms that induce a possible priming effect. The acquisition of this
knowledge will facilitate future breeding programs providing novel stress response markers.
References
Crisp et al. (2016) 10.1126/sciadv.1501340
Delamare, J. et al. (2023) https://doi.org/10.1016/j.envexpbot.2023.105318
Ding, Y. et al. (2012) https://doi.org/10.1038/ncomms1732
Gallusci, P. et al. (2023) https://doi.org/10.1016/j.tplants.2022.09.004
Kinoshita and Seki (2017) https://doi.org/10.1093/pcp/pcu125
Lämke, J. and Bäurle, I. (2017) https://doi.org/10.1186/s13059-017-1263-6
Liu, H. et al. (2022) https://doi.org/10.1016/j.tplants.2021.11.015
Magno, L. et al. (2021) https:// doi.org/10.1016/j.envexpbot.2021.104400
Pratx, L. et al. (2023). https://doi.org/10.15252/embj.2023113595
Serrano, N. et al. (2019) https://doi.org/10.1038/s41598-018-36484-z
Wang, X. et al (2017) https://doi.org/10.1016/S2095-3119(17)61786-6
| Keywords | Oilseed rape, Heat stress, Seed quality, Memory, Priming |
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