High Photosynthetic Capacity in a Shade-Tolerant Crassulacean Acid Metabolism Plant (Implications for Sunfleck Use, Nonphotochemical Energy Dissipation, and Susceptibility to Photoinhibition)

Abstract

Aechmea magdalenae André ex Baker, a constitutive Crassulacean acid metabolism (CAM) plant from the shaded Panamanian rain forest understory, has a maximum photosynthesis rate 2 to 3 times that of co-occurring C, species and a limited potential for photosynthetic acclimation to high light. Chlorophyll fluorescence measurements indicated that (a) compared with co-occurring C, species, photosynthetic electron transport in A. magdalenae responded more rapidly to light flecks of moderate intensity, attained a higher steady-state rate, and maintained a lower reduction state of plastoquinone during light flecks; (b) these characteristics were associated with phase III CO, fixation of CAM; (c) when grown in full sun, A. magdalenae was chronically photoinhibited despite a remarkably high nonphotochemical quenching capacity, indicating a large potential for photoprotection; and (d) the degree of photoinhibition was inversely proportional to the length of phase 111. Results from the light fleck studies suggest that understory A. magdalenae plants can make more efficient use of sun flecks for leaf carbon gain over most of the day than co-occurring C, species. The association between the duration of phase III and the degree of photoinhibition for A. magdalenae in high light is discussed in relation to the limited photosynthetic plasticity in this species.

Novel Cyclotides and Uncyclotides with Highly Shortened Precursors from Chassalia chartacea and Effects of Methionine Oxidation on Bioactivities

“…One possible explanation is that C. chartacea is an understory tree where sunlight is a limiting factor as opposed to the African species O. affinis, which is grown in full sunlight. When less light is available, less energy is available for the plants, and most understory plants evolve to be efficient energy users (34). The reduced size of the cyclotide precursors may provide an economic advantage for plants as less energy will be required for producing cyclotides.…”

Adaptive radiation, correlated and contingent evolution, and net species diversification in Bromeliaceae

“…The high diversity of CAM epiphytic bromelioids in the Atlantic Forest region may primarily reflect this advantage of CAM. Other factors that may help account for the presence of CAM epiphytes in shaded, rainy microsites -despite the relatively small additional energetic cost of CAM vs. C 3 photosynthesis (Winter and Smith, 1996a,b) -include (1) efficient use of sunflecks for carbon gain during Phase III when intercellular CO 2 is high (Skillman and Winter, 1997), and (2) greater allocation to light-absorbing foliage and less to roots, at least in the CAM terrestrial Aechmea magdalenae vs. sympatric C 3 species (Skillman et al, 1999).…”

Microambientes lumínico y morfología y fisiología foliar de Bromelia karatas (Bromeliaceae) en una selva baja caducifolia de Yucatán, México

“…Durante la temporada de sequía, como respuesta al exceso de luz, los tejidos de las hojas de plantas expuestas y de sombra de B. karatas disminuyeron el contenido de clorofi las e incrementaron el contenido de carotenoides. En las hojas expuestas de algunas bromeliáceas terrestres, como Aechmea magdalenae y B. humilis, se incrementa el contenido de pigmentos del ciclo de las xantofi las, lo que reduce el daño oxidativo por saturación de luz y que además está relacionado con la disipación del exceso de energía (Königer et al, 1995;Skillman y Winter, 1997;Müller et al, 2001;Havaux et al, 2007;Matsubara et al, 2009). En diferentes grupos de plantas aclimatadas a alta intensidad lumínica, la tendencia general es el decremento de la actividad fotosintética, en donde una disminución en los valores de la efi ciencia fotosintética del fotosistema II (ΦPSII) probablemente se deba a la disipación de calor (Demmig-Adams et al, 1995).…”

“…La familia Bromeliaceae tiene una amplia distribución en un extenso intervalo de condiciones ambientales y presenta una gran variación morfo-anatómica y de formas de vida, con especies adaptadas a sitios totalmente expuestos a la luz y otras adaptadas a la sombra (Martin, 1994;Skillman y Winter, 1997;Benzing, 2000). En las selvas bajas caducifolias de Yucatán coexisten varias plantas CAM, terrestres y epifi tas, adaptadas a los cambios de la intensidad de luz y disponibilidad de agua durante el año, que muestran cambios en la fotosíntesis y en la producción de metabolitos foliares en respuesta al ambiente lumínico (González-Salvatierra et al, 2010;Ricalde et al, 2010).…”