Determination of the resurrection phenomenon and repare mechanisms in Polytrichaceae (Bryophyta)

• Grant number: 22/12711-8
• Support Opportunities: Regular Research Grants
• Start date: April 01, 2023
• End date: September 30, 2025
• Field of knowledge: Biological Sciences - Botany - Applied Botany
• Principal Investigator: Déborah Yara Alves Cursino dos Santos
• Grantee: Déborah Yara Alves Cursino dos Santos
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: Cristiane Paula Gomes Calixto ; Fanly Fungyi Chow Ho ; Gladys Flávia de Albuquerque Melo de Pinna
• Associated scholarship(s): 24/04273-6 - Cultivation and maintenance of Polytrichaceae species in a greenhouse, BP.TT; 24/04165-9 - Evaluation of differentially expressed transcripts in moss species subjected to conditions of water restriction and increased UV-B radiation., BP.TT

Abstract

Bryophytes sensu lato were the first embryophytes that faced the typical adversities of the terrestrial environment. The mechanisms of tolerance to desiccation and UV radiation ensured the success in this new environment. Many of these plants, including species of Polytrichaceae, are characterized as " "resurrection species", which means they can remain viable for long periods of anabiosis and return their vital processes in a few seconds. Resurrection species has already been reported in four genera of Polythricaceae, one of them Polytrichum. In this context, the main goals of this project are (i) to verify the presence of the resurrection phenomenon in native species of Polytrichaceae that have not yet been investigated, (ii) to evaluate whether this characteristic can influence the repair mechanism to the increase in UV-B radiation, using a already known resurrection species (Polytrichum juniperinum Hedw.) and a non-resurrection species (SP1 - to be defined). To determine the resurrectiion phenomenon, gametophytes of Polytrichaceae species will be collected in the state of São Paulo and will be evaluate through physiological and anatomical parameters in anabiosis and hydrated conditions. The physiological parameters will be: (a) determination of relative water content (CRA), (b) fluorescence measurements (effective quantum yield (PSII) and maximum quantum yield (Fv/Fm) and apparent electron transport rate (ETR), (c) pigment content (chlorophyll a, b and carotenoids), (d) lipid peroxidation level (MDA), (e) activity of enzymatic (CAT, APX, GR and SOD) and non-enzymatic (ascorbic acid and glutathione) antioxidants and, (f) DPPH radical scavenging capacity. Anatomical investigation will be conducted through optical microscopy. To investigate the influency of resurrection capacity in the tolerance to another stress (eg increased UV-B radiation) gametophytes of P. juniperinum and SP1 will be transferred to pots and kept in a growth chamber under controlled conditions for two weeks. Then, the pots will be arranged into 4 groups: (1) control; (2) water restriction for six days followed by rehydration and sample collection at T=0, T=15 min and T=30 min; (3) increased UV- B for 3 hours/day and sample collection after 5 and 10 days; and (4) increased radiation UV-B for 3 hours/day for 5 and 10 days after a water restriction cycle. Before samples collections, fluorescence measurements will be carried out and then the samples will be collected and stored properly until the analyzes described above are carried out. In addition, samples will be collected for analysis of differentially expressed transcripts using the RNA-seq technique. Data from each experiment will be statistically treated and compared with control. In this way, the analysis of the parameters proposed in this project can help in the understanding, from a broad and robust view, of several events involved in the responses of these plants to environmental factors, besides opening a range of new research possibilities due to molecular global analysis. (AU)