Changes to the functional traits of phosphoenolpyruvate carboxylase following hybridization in C-4 halophytes

Authors: GALLEGO-TEVAR, BLANCA - University Of Sevilla; PEINADO, PROCOPIO - University Of Sevilla; ALVAREZ, ROSARIO - University Of Sevilla; GANDULLO, JACINTO - University Of Seville; Grewell, Brenda; FIGUEROA, ENRIQUE - University Of Sevilla; CASTILLO, JESUS - University Of Sevilla

Submitted to: Physiologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2019
Publication Date: 11/29/2019
Citation: Gallego-Tevar, B., Peinado, P., Alvarez, R., Gandullo, J., Grewell, B.J., Figueroa, E., Castillo, J.M. 2019. Changes to the functional traits of phosphoenolpyruvate carboxylase following hybridization in C-4 halophytes. Physiologia Plantarum. 169(1):83-98. https://doi.org/10.1111/ppl.13053.
DOI: https://doi.org/10.1111/ppl.13053

Interpretive Summary: Following establishment and invasive spread of alien plant species, often hybridization between native congeners and the invaders is a secondary effect of invasion. The implications of these hybridization events for evolution and ecology of plant species and their impacts on recipient communities are not fully understood. Improved knowledge of how interspecific hybridization influences mechanistic traits with clear physiological functions that can drive evolutionary and ecological processes is needed to better understand invasions and their management. Interspecific hybridization is a frequent and relevant evolutionary mechanism, but little is known about its effects on the responses of key enzymatic activities to environmental stress factors. We analyzed the effects of salinity on key mechanistic of phosphoenolpyruvate carboxylase (PEPC), one of the main enzymes involved in photosynthesis of C4 plants, for two different hybrids between the cordgrasses Spartina maritima and S. densiflora in comparison with their parental species. The inheritance mechanisms that lead to different hybrid behaviors, as well as the net photosynthesis rate and free proline accumulation as a stress indicator were recorded. Parental species showed contrasted strategies at the PEPC level to cope with salinity. Native S. maritima showed its physiological optimum from 10 to 40 ppt, keeping constant PEPC specific activity (due to high enzyme contents), while the alien invasive species S. densiflora had its salinity optimum between 0.5 and 10 ppt, where it presented its highest levels of PEPC specific activity (coinciding with high light-induced activation of PEPC). Both hybrids showed constant PEPC specific activity from fresh water to hypersalinity and exhibited higher net photosynthesis rates at fresh water than their parents. S. maritima x densiflora was the only taxon able to increase its PEPC activation level (IC50) in darkness and light at high salinities. Thus, S. maritima x densiflora presented three functional PEPC-related traits different from its both parental species due to transgressive segregation, whereas S. densiflora x maritima showed most PEPC-related traits intermediate between its parental species.

Technical Abstract: Interspecific hybridization is a frequent and relevant evolutionary mechanism, but little is known about its effects on the responses of key enzymatic activities to environmental stress factors. We analyzed the effects of salinity on key mechanistic of phosphoenolpyruvate carboxylase (PEPC), one of the main enzymes involved in photosynthesis of C4 plants, for two different hybrids between the cordgrasses Spartina maritima and S. densiflora in comparison with their parental species. The inheritance mechanisms that lead to different hybrid behaviors, as well as the net photosynthesis rate and free proline accumulation as a stress indicator were recorded. Parental species showed contrasted strategies at the PEPC level to cope with salinity. Native S. maritima showed its physiological optimum from 10 to 40 ppt, keeping constant PEPC specific activity (due to high enzyme contents), while the alien invasive species S. densiflora had its salinity optimum between 0.5 and 10 ppt, where it presented its highest levels of PEPC specific activity (coinciding with high light-induced activation of PEPC). Both hybrids showed constant PEPC specific activity from fresh water to hypersalinity and exhibited higher net photosynthesis rates at fresh water than their parents. S. maritima x densiflora was the only taxon able to increase its PEPC activation level (IC50) in darkness and light at high salinities. Thus, S. maritima x densiflora presented three functional PEPC-related traits different from its both parental species due to transgressive segregation, whereas S. densiflora x maritima showed most PEPC-related traits intermediate between its parental species.