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| Author(s): |
Yohans Alves de Moura
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2023-09-26 |
| Examining board members: |
Anete Pereira de Souza;
Maria Imaculada Zucchi;
Bianca Baccili Zanotto Vigna;
Mirian Perez Maluf
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| Advisor: | Anete Pereira de Souza; Alessandro Alves Pereira |
| Abstract | |
Mangroves are coastal ecosystems of great socio-environmental importance and are highly threatened by human activities. Mangrove trees live under harsh environmental conditions, which makes them sensitive to extreme weather events, particularly freezing ones. Such events are unpredictable and have catastrophic consequences, therefore understanding and anticipating their impacts is essential for directing future mitigation measures. The freezing cold currently limits the distribution of mangroves to tropical and subtropical latitudes in the world, trees are seriously affected in these situations and suffer severe metabolic lows due to damage to photosystems and cellular structures. Land plants have developed sophisticated mechanisms of resistance to freezing during their evolution, currently the knowledge about the central molecular mechanisms involved in this process is consistent. However, the information is restricted to herbaceous models native to temperate habitats such as Arabidopsis thaliana, there is a gap related to tropical trees such as mangroves. This thesis aims to advance knowledge about the molecular aspects involved in the response and tolerance to freezing of mangrove trees using Avicennia schaueriana as a model. This species is occurs in the colder limits of the South American mangroves, and shows evidence of the existence of two functional groups locally adapted to the equatorial (EQ) and subtropical (ST) portions of the Brazilian coast. We investigated the transcriptional profile of seedlings from both functional groups under freezing shock (-4°C) in a time series. We analyzed transcriptome data by combining differential expression, coexpression networks and protein interaction techniques. Our results allowed us to describe the profile of the molecular response to freezing of A.schaueriana and the divergence in the behavior of the EQ and ST functional groups. In EQ, the response is strongly based on abscisic acid action and stress signals throughout the experiment. This negatively affects growth, and promotes the accumulation of carotenoids, anthocyanin and lipids based on chlorophyll degradation. On the other hand, in ST, there are fewer hormones active in the process and signs of maintenance of primary growth and metabolic normalization. The accumulation of substances is mainly based on sucrose, anthocyanin and lipids, the latter not dependent on chlorophyll degradation. Based on these results, we hypothesize that the susceptibility to freezing damage is greater in EQ when compared to ST. Therefore, we recommend that this fact be considered in the management of this species, especially at higher latitudes, which are more prone to the occurrence of lower temperatures and extreme freezing events (AU) | |
| FAPESP's process: | 19/21100-0 - Molecular attributes of tropical tree Avicennia schaueriana involved in low temperature tolerance |
| Grantee: | Yohans Alves de Moura |
| Support Opportunities: | Scholarships in Brazil - Doctorate |