Comparative Study of the C₃/CAM Intermediate Species Clusia parviflora Saldanha et Engi. and the Obligate CAM Species Clusia hilariana Schlecht. Growing Sympatrically Exposed and Shaded in the Coastal Restinga of Brazil

Abstract

The C3/CAM intermediate species, C/usia parviflora Saldanha et EngI., and the obligate CAM species Clusia hilariana Schlecht., occur sympatrically in the coastal sand dune vegetation of the Restinga of Brazil. Their photosynthetic activity at an exposed and at a shaded site was compared by measuring gas exchange (porometry), chlorophyll a fluorescence parameters, organic acid levels (malic and citric) and carbon isotope ratios. At the shaded site, low photosynthetic photon flux densities (PPFD) strongly restricted photosynthetic activity. However, C parviflora could readily make use of light flecks. At the exposed site, C. parviflora was much less affected by photoinhibition than C. hilariana. The CAM species showed higher apparent rates of linear photosynthetic electron transport (ETR) and higher effective quantum yield of PSII (ΔF/F'm) than did C. parviflora during high insolation in the middle of the day, i.e., the time of Phase Ill of CAM. Nevertheless, it suffered much more severe acute photoinhibition that was not reversible after 20 min of darkening during this time, and even some chronic photoinhibition not reversible overnight. Comparative studies of sympatric physiotypes with different modes of photosynthesis of a given leaf morphotype, as available in the genus Cksia, challenge some CAM dogmas, e.g., CAM may not always be superior at exposed sites and may not always provide better photoprotection at high PPFD. However, the idea that C3/CAM plasticity allows occupation of a wider range of habitats is supported.

Ecophysiology of selected tree species in different plant communities at the periphery of the Atlantic Forest of SE Brazil I. Performance of three different species of Clusia in an array of plant communities

“…Interestingly, there were no significant site effects on δ 13 C of leaves (separate data for sites not shown), i.e., wetter versus drier sites, for both C. fluminensis and C. hilariana, indicating that overall the influence of different rainfall and site hydrology was negligible. Hence, the data confirm expectations from the literature that in the field both C. fluminensis (Roberts et al 1996(Roberts et al , 1997 and C. hilariana (Franco et al 1996(Franco et al , 1999Mattos et al 1997;Herzog et al 1999b) were CAM-performing.…”

“…Intra-and interspecific comparisons were made by ANOVA followed by Tukey HSD post-hoc test. (Herzog et al 1999b), although when stressed under phytotron conditions it may show a certain CAM capacity (Grams et al 1998). Conversely, the much less negative values obtained for C. fluminensis and C. hilariana show that they perform CAM.…”

“…However, the δ 13 C of −30.7‰measured in this study and of −30.1‰in the previous study of de Mattos et al (1997) implies that the overall soil water availability is not a limiting factor in this particular inselberg. Indeed, C. parviflora and C. hilariana co-occur in some sites of the Jurubatiba restinga (Herzog et al 1999b), characterised by a high water table. In these sites C. parviflora is more abundant in shaded or partially shaded sites.…”

One Morphotype, Three Physiotypes: Sympatric Species of Clusia with Obligate C3 Photosynthesis, Obligate CAM and C3‐CAM Intermediate Behaviour

“…)unpubhshed 0C values) C. hilariana Schlecht [18,42,19,32] C. intertexta Britt. [10] C. lanceolata Camb.…”

Phosphoenolpyruvate carboxylase genes in C3, crassulacean acid metabolism (CAM) and C3/CAM intermediate species of the genus Clusia: rapid reversible C3/CAM switches are based on the C3 housekeeping gene

“…1992;Zotz & Winter 1993;Haag-Kerwer et al . 1996;Grams, Herzog & Lüttge (1998); Herzog et al . 1999).…”