? 13C values and crassulacean acid metabolism in Clusia species from Panama

Abstract

The genus Clusia is notable in that it contains arborescent crassulacean acid metabolism (CAM) plants. As part of a study of CAM in Clusia, titratable acidities were measured in 25 species and í i^c values were measured for 38 species from Panamá, including seven undescribed species, and 11 species from Colombia, Costa Rica and Honduras. CAM was detected in 12 species. Clusia flava, C rosea and C. uvitana exhibited Í l^C values or diurnal fluctuations in acidity indicative of strong CAM. In C. croatii, C cylindrica, C. fructiangusta, C lineata, C odorata, C pratensis, C quadrangula, C. valerioi and C. sp. D diurnal fluctuations in acidity were consistent with weak CAM but the Í i^C values were Cß-like. AU of the species that exhibited strong or weak CAM were in the C. flava or C. minor species groups. CAM was not detected in any member of the C. multiflora species group. Strong CAM species were not collected at altitudes above 680 m a. s.l. On the basis of ^^^C values, the expression of CAM was similar in terrestrial, hemiepiphytic and epiphytic species and did not differ between individuals of the same species http://www.springerlink.com/media/ECXX5U63F83JUG8CA...butions/LA'/N/J/LVNJBJQ2KGNTAVP7_html/fulltext.html (1 of 39)6/5/2004 1:09:18 PM 10.1007/s00468-004-0342-y that exhibited different Hfe-forms. This study indicates that phylogenetic affihation may be a predictor of an ability to exhibit CAM in Clusia species from the Panamanian region, and that weak CAM is probably a common photosynthetic option in many Clusia species. í l^C value is not a particularly good indicator of a potential of Clusia species growing in the field to exhibit CAM because it appears that the contribution in most species of CAM to carbon gain is generally rather small when integrated over the life-time of leaves.

Carbon isotope composition and water-use efficiency in plants with crassulacean acid metabolism

“…Although C. pratensis had high background levels of titratable acidity, it did not exhibit significant nocturnal acid accumulation in this experiment (Fig. 1); in other experiments it has been shown to have the ability to express weak CAM (Holtum et al 2004). In general, the δ 13 C values of individual representative mature leaves of the Clusia species were similar to δ 13 C values of the bulk dry mass of whole shoots, suggesting that the δ 13 C value of representative mature leaves can be a reasonable indicator of whole-plant CAM expression (Table 3).…”

“…E [an identified but yet to be named species that corresponds to Clusia sp. E in Gehrig et al (2003) and Holtum et al (2004)], which were grown at the Smithsonian Tropical Research Institute Santa Cruz Experimental Field Facility in Gamboa, Republic of Panama. Plants were maintained under a permanent rain shelter consisting of a 4 × 8-m concrete floor and a 6 × 10-m translucent glass roof at 3-3.5 m height.…”

“…The experiments were performed in a relatively humid tropical environment where CAM species are abundant (Winter et al 1983;Earnshaw et al 1987;Holtum and Winter 1999;Gehrig et al 2003;Crayn et al 2004;Holtum et al 2004), but where investigations on water relations of these plants have been few in comparison to those on CAM succulents from semi-deserts (Nobel 1988). Included in our study was an investigation of TR in seven species of Clusia, a genus of ∼300 species native to wet and seasonally dry tropics and sub-tropics in the New World (Hammel 1986;Pipoly et al 1998).…”

Evolution along the crassulacean acid metabolism continuum

“…Just as increased leaf thickness and concomitant increase in storage capacity for malic acid confer a selective advantage for committing to CAM, if, in CAM plants, increased leaf succulence and associated decreases in g i indeed affect CO 2 uptake in the light more than in the dark (Nelson and Sage 2008), then, evolutionary progression from the C 3 to CAM state would appear to favour either retention of C 3 photosynthesis or full conversion to CAM, but not the intermediate state. Indeed, such a pattern is reflected in differences in high and low IAS and L mes /area values between weak and strong CAM species (Nelson and Sage 2008), as well as the bimodal distribution of d 13 C values observed in large surveys of plant families with mixtures of C 3 /weak CAM and CAM species (see text below) (Zotz and Ziegler 1997;Pierce et al 2002;Crayn et al 2004;Holtum et al 2004;Silvera et al 2005Silvera et al , 2009Silvera et al , 2010.…”

The effects of salinity, crassulacean acid metabolism and plant age on the carbon isotope composition of Mesembryanthemum crystallinum L., a halophytic C3-CAM species

“…Winter et al 1983;Earnshaw et al 1987;Crayn et al 2004;Holtum et al 2004). If C 4 photosynthesis is absent, d 13 C values permit the assignment of plants as either C 3 or as crassulacean acid metabolism (CAM), provided the latter species obtain roughly 30% or more of their carbon via phosphoenolpyruvate carboxylase (PEPC)-catalysed bcarboxylation.…”