Duarte et al. 2024 (Article) Brazil

Are CAM bromeliad seedlings from Campo Rupestre more tolerant to heat than C3?

Author(s):—A.A. Duarte, T. Vilas-Boas, A.R. Marques & J.P. de Lemos-Filho

Publication:—Theoretical and Experimental Plant Physiology online: 1-16. (2024) — DOI

Abstract:—Temperature stress is an important filter for recruitment as it can lead to significant seedling mortality. In this study, we examined the impacts of temperature on the performance of seedlings of seven bromeliads species from Campo Rupestre (a high elevation savanna-like vegetation) evaluating growth, mortality, chlorophyll a fluorescence, and Photosystem II (PSII) heat tolerance (PHT) aiming to address three primary questions: (1) Do seedlings of bromeliad species with different photosynthetic pathways (C3 or CAM) exhibit different growth responses to temperature? (2) Are there differences in PHT between seedlings from C3 and CAM species? (3) Does the PHT change depending on the growth temperature? Regardless of the photosynthetic pathway, it was evident that 25 °C was the temperature favouring the performance of most species’ seedlings. Beyond this temperature, CAM species’ seedlings displayed a higher relative growth rate (RGR), greater maximum quantum yield (FV/Fm), and higher temperature for 50% lethality (LT50) as compared to C3 species. The PHT exhibited variation according to the seedling's growth temperature, indicating a remarkable capacity for adjusting the photosynthetic apparatus in bromeliad seedlings. Our data revealed a correlation between PHT and seedling growth but not with mortality. Additionally, we found no relationship between the thermal niche breadth for growth and the acclimation capacity of PSII to the growth temperatures. Seedlings of CAM species exhibited higher heat tolerance than C3 species, yet significant variation in heat tolerance was observed among species based on their growth habits and microhabitats.