Plasticity of crassulacean acid metabolism at subtropical latitudes: a pineapple case study

Abstract

Plants with the crassulacean acid metabolism (CAM) express high-metabolic plasticity, to adjust to environmental stresses. This article hypothesizes that irradiance and nocturnal temperatures are the major limitations for CAM at higher latitudes such as the Azores (37°45'N). Circadian CAM expression in Ananas comosus L. Merr. (pineapple) was assessed by the diurnal pattern of leaf carbon fixation into l-malate at the solstices and equinoxes, and confirmed by determining maximal phosphoenolpyruvate carboxylase (PEPC) activity in plant material. Metabolic adjustments to environmental conditions were confirmed by gas exchange measurements, and integrated with environmental data to determine CAM's limiting factors: light and temperature. CAM plasticity was observed at the equinoxes, under similar photoperiods, but different environmental conditions. In spring, CAM expression was similar between vegetative and flowering plants, while in autumn, flowering (before anthesis) and fructifying (with fully developed fruit before ripening) plants accumulated more l-malate. Below 100 µmol m(-2) s(-1) , CAM phase I was extended, reducing CAM phase III during the day. Carbon fixation inhibition may occur by two major pathways: nocturnal temperature (<15°C) inhibiting PEPC activity and l-malate accumulation; and low irradiance influencing the interplay between CAM phase I and III, affecting carboxylation and decarboxylation. Both have important consequences for plant development in autumn and winter. Observations were confirmed by flowering time prediction using environmental data, emphasizing that CAM expression had a strong seasonal regulation due to a complex network response to light and temperature, allowing pineapple to survive in environments not suitable for high productivity.

Ecophysiological responses of ´Turiaçu´ pineapple plants at vegetative and reproductive stages to soil fertilization and crop location

“…This confirms that the organic fertilization used or its application management was a source of stress for the ´Turiaçu` pineapple plants. The less favorable the climate conditions for the pineapple, the lower the WUE (RAINHA et al, 2016). This was confirmed by the results of plants grown under organic fertilization in São Luís.…”

“…The plants grown in São Luís presented lower Chlorophyll index and Fv/Fm, indicating that this location presented less favorable climate conditions for the photosynthetic activity than Turiaçu, such as higher minimum temperature, higher atmospheric demand, and lower maximum relative air humidity (BRITO et al, 2017;RAINHA et al, 2016;WILLIAMS et al, 2017). This was probably due to the climate conditions of São Luís, since the soil in São Luís was more fertile than that in Turiaçu according to soil chemical characteristics of the municipalities (Table 1).…”

“…The less favorable climate conditions in São Luís, regardless of the seasons, resulted in plants with lower stomatal conductance (up to 90.0% lower in the dry, and up to 66.6% lower in the rainy season) and lower transpiration (up to 70.1% lower in the dry, and up to 53.7% lower in the rainy season) when compared to those grown in Turiaçu. Decreases in stomatal conductance and increases in resistance to gas exchange are the first responses of plants to water deficit conditions, since they reduce the opening of stomata, reducing water loss by transpiration (LAWSON & BLATT, 2014;RAINHA et al, 2016;TAIZ et al, 2017).…”

Genome-Wide Identification and Characterization of Xyloglucan Endotransglycosylase/Hydrolase in Ananas comosus during Development

“…The contrasting expression patterns in the green leaf tip and white leaf base was suggestive of tissue specificity of XTHs in pineapple. Pineapple fixes carbon dioxide nocturnally by activity of CAM-related enzymes and is stored rapidly as malic acid in the vacuole [2,63]. Ac(MD2)XTH15, Ac(MD2)XTH11, Ac(MD2)XTH6, and Ac(MD2)XTH20 showed higher expression levels in photosynthetic tissues and may be putative CAM-related genes that enhance the efficiency of water use by the CAM pathway.…”

Como o gradiente altitudinal de luz no sub-bosque afeta as características estruturais e fisiológicas de hemiepífitas: o caso de Vanilla bahiana Hoehne (Orchidaceae)

“…Todas essas fases exibem plasticidade em termos de intensidade e duração sob diferentes condições ambientais, como disponibilidade de água, intensidade, qualidade e duração da iluminação (Nobel & Hartsock 1983;Ceusters et al 2014;. Em resposta a variação climática, a expressão do CAM pode exibir uma regulação sazonal (Rainha et al 2016). Por exemplo, do ponto de vista fisiológico, foi observado maior acúmulo de acidez noturna e menor eficiência quântica durante a estação seca, quando a incidência de radiação fotossinteticamente ativa (RFA) é maior, comparada às estações de seca média e úmida (de la Rosa-Manzano et al 2014).…”