Apoplastic and symplastic phloem loading in Quercus robur and Fraxinus excelsior.

ABSTRACT: Whereas most of the research on phloem loading is performed on herbaceous plants, less is known about phloem loading strategies in trees. In this study, the phloem loading mechanisms of Quercus robur and Fraxinus excelsior were analysed. The following features were examined: the minor vein structure, the sugar concentrations in phloem sap by the laser-aphid-stylet technique, the distribution of photoassimilates in the mesophyll cells by non-aqueous fractionation, gradients of sugar concentrations and osmotic pressure, and the expression of sucrose transporters. The minor vein configurations of Q. robur and F. excelsior belong to the open type. Quercus robur contained companion cells in the minor veins whereas F. excelsior showed intermediary cells in addition to ordinary companion cells. T

SUBMITTER: Oner-Sieben S 

PROVIDER: S-EPMC3978624 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature