TITLE:
High Light Intensity Increases the CAM Expression in “MD-2” Micro-Propagated Pineapple Plants at the End of the Acclimatization Stage
AUTHORS:
René C. Rodríguez-Escriba, Romelio Rodríguez, Dariel López, Gustavo Y. Lorente, Yaima Pino, Carlos E. Aragón, Yolanda Garza, Florencio E. Podestá, Justo L. González-Olmedo
KEYWORDS:
Crassulacean Acid Metabolism, Hardening Stage, Ex Vitro, Vitroplants, Gaseous Exchange
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.6 No.19,
December
10,
2015
ABSTRACT: This work describes the evaluation of morpho-physiological and biochemical changes in “MD-2”
micro-propagated pineapple plants (Ananas comosus (L.) Merr.) grown after 30 days under low
light intensity (LL, greenhouse light conditions at 250 μmol·m-2·s-1) or high light intensity (HL,
field light conditions at 800 μmol·m-2·s-1). Gas exchange, leaf pH, protein content and superoxide
dismutase activity (SOD) (EC 1.15.1.1) were measured every 3 h during one day. Chlorophylls
content and succulence index (SI) were determined at 9 h. Results showed significant differences
in CO2 exchange rates, with a maximum occurring at 6 h (3.00 and 8.25 μmol CO2 m-2·s-1 for leaves
under LL and HL conditions respectively). Plants under HL conditions had higher CO2 uptake and
lower pH values between 0 h and 6 h respective to LL plants. The maximum pH value was attained
3 h before in HL plants. Leaf SI was increased and chlorophyll content decreased by HL conditions.
SOD activity was higher in plants under HL conditions, near doubling those of LL plants at 18 h (2.8
versus 1.5 U·mg-1 Protein respectively). Both groups showed a typical CAM phenotype, but it was
stronger in HL conditions, which may confer these plants with a better acclimation to transfer to
the field.