The physiology of ex vitro pineapple (Ananas comosus L. Merr. var MD-2) as CAM or C3 is regulated by the environmental conditions

Abstract

Many plant species grown under in vitro controlled conditions can be used as models for the study of physiological processes. Adult pineapple can display CAM physiology while in vitro it functions as a C3 plant. Ex vitro Ananas comosus has plastic morphology and physiology, both easy to modify from C3 to CAM by changing the environmental conditions. The yield of survival for a rentable propagation protocol of pineapple is closely related with the C3/CAM shift and the associated physiological characteristics. In the present work, ex vitro pineapple plants were divided in two sets and subjected to C3 and CAM-inducing environmental conditions, determined by light intensity and relative humidity, respectively, 40 μmol m(-2) s(-1)/85% and 260 μmol m(-2) s(-1)/50%. The results demonstrated that the stress imposed by the environmental conditions switched pineapple plants from C3 to CAM behavior. Comparing to CAM induced, C3-induced pineapple plants showed substandard growth parameters and morphological leaf characteristics but a better rooting process and a higher ABA production, a phenotype closer to adult plants, which are expected to produce fruits in a normal production cycle. We conclude that the upholding of these characteristics is conditioned by low light intensity plus high relative humidity, especially during the first 8 weeks of ex vitro growth. It is expected that the better understanding of pineapple acclimatization will contribute to the design of a protocol to apply as a rentable tool in the pineapple agronomic industry.

Proline levels, oxidative metabolism and photosynthetic pigments during in vitro growth and acclimatization of Pitcairnia encholirioides L.B. Sm. (Bromeliaceae)

“…The growth regulator, flask closure system and sucrose concentration in the culture medium affect plantlet survival in acclimatization, since these factors may affect the metabolism, modifying the morphological and physiological characteristics of the plants (Lucchesini and Mensuali-Sodi, 2004;Sáez et al, 2012). In addition to the modifications of in vitro culture conditions, several acclimatization procedures can be used, especially those which prevent water loss and biochemical disorders (Aragón et al, 2012).…”

Morpho-physiological changes in pineapple plantlets [Ananas comosus (L.) merr.] during acclimatization

“…Plant length was significantly less after 15 and 30 d than it was at day 0, but by day 45 had regained the height at day 0. Aragon et al (2012) found that stress imposed by water deficit and higher photosynthetic photon flux switched pineapple plants from C3 to CAM behavior. In our results we can find more number of roots, higher fresh weight and photosynthetic activity at 45 d in acclimatization period to report for this author at 56 d in CAM induced pineapple.…”

High Light Intensity Increases the CAM Expression in “MD-2” Micro-Propagated Pineapple Plants at the End of the Acclimatization Stage

“…Leaves pH determination: Six fresh D-leaves of plants were collected every 3 h for 24 h. Samples were crushed and 0.5 ml of the resulting fluid were collected, clarified by addition of activated charcoal and centrifuged at 12,000 g during 5 min. Supernatant pH was immediately quantified with pH indicator strips (Merck KGaA 64,271) according to Aragón et al (2012) [13].…”

“…Temperature determines the occurrence of C 3 or CAM photosynthesis in pineapple plantlets grown under in vitro conditions [11], this behavior is also modulated by nitric oxide and water availability [12]. Besides C 3 or CAM metabolism in pineapple plantlets was conditioned by a combination of low relative humidity, and high temperatures and light intensity during the 4 first weeks of ex vitro growth [13] [14]. It is known that adult macro-propagated pineapple plants are classified like "strong constitutive CAM plants" [15]- [18].…”