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Structural variation among leaves in Aechmea distichantha Lem. (Bromeliaceae) rosettes, considering apical and basal differences

Hermes, Manoela Bordignon, Moreira, Ana Silvia Franco Pinheiro, Castro, Neuza Maria de, Oliveira, Denis Coelho de
Flora 2018 v.248 pp. 76-86
Aechmea, antibodies, cell walls, chlorenchyma, epitopes, leaves, pectins, photosynthesis
In tank-dependent bromeliads, leaves may exhibit anatomical and functional differences along the apical and basal regions, or according to the different positions in the rosette. Thus, the apical region of the leaf may invest in photosynthetic tissues, while the basal one invests in structures for water and nutrient storage. We suppose here, that differences among the tissue functions are strongly related to anatomical traits, especially the degree of methyl-esterification of pectins in the cell walls, at different positions along the rosette. Thus, the aims of this study were to quantify anatomical variations and describe the pectin composition of the cell wall, along the Aechmea distichantha Lem. rosette, to assess how the different tissues varied. We found that the water storage tissue showed higher variation between the apex and the base of the leaves than the other tissues, with higher expansion between the fourth leaf in development and the outer leaf in the rosette. Moreover, its cells were intensely labeled for epitopes of high methyl-esterified HGs, recognize by JIM7 antibody. The presence of pectin with high methyl-esterified groups in water storage tissue provides greater cell wall elasticity. The chlorenchyma showed the lowest Relative Distance Plasticity Index values, and its development in A. distichantha seems to occur early, in a very young leaf and inside the rosette tank.