caa a22 4500 477101240 CHVBK 20180405111542.0 cr unu---uuuuu 170330e19960201xx s 000 0 eng 10.1007/BF00206241 doi (NATIONALLICENCE)springer-10.1007/BF00206241 Significance of minor-vein anatomy to carbohydrate transport [Elektronische Daten] [Linda Flora, Monica Madore] Plant species which translocate distinct combinations of carbohydrates in the phloem were investigated to assess whether differences in minor-vein anatomy were associated with differences in carbohydrate composition of the phloem sap. In Vicia faba L., a species in which the minor-vein companion cells are modified into transfer cells, sucrose alone was found to be the translocated form of carbohydrate. In Vicia, phloem transport of sucrose was inhibited by pretreatment of leaves with p-chloromercuribenzenesulfonic acid (PCMBS), a known inhibitor of the sucrose carrier. In contrast, in Ocimum basilicum L., a species in which the minor-vein companion cells are of the symplasmically linked intermediary cell type, both sucrose- and raffinose-family oligosaccharides were exported in the phloem. In this species, no PCMBS sensitivity was observed for phloem transport of either sucrose- or raffinose-family oligosaccharides, although a PCMBS-sensitive sucrose carrier was detected in leaf tissues. This carrier did not appear to be involved in phloem loading, rather, it appeared that phloem loading occurred via the symplasm in this species. In the polyoltranslocating species Petroselinum crispum L., the same insensitivity to PCMBS was seen, suggesting that symplasmic phloem loading also occurred. The companion cells were symplasmically connected to the surrounding bundle-sheath cells by numerous "H”-shaped plasmodesmata but were not intermediary cells, and no raffinose oligosaccharides were exported by Petroselinum. Taken together, the data indicate that apoplasmic transport may be responsible for phloem loading in species in which sucrose alone is exported. However, in those plant species in which a combination of sucrose and any other carbohydrate, including the polyols, is translocated, symplasmic phloem loading may predominate. Springer-Verlag, 1996 Apoplasmic nationallicence Phloem loading nationallicence Polyol nationallicence Raffinose oligosaccharide nationallicence Symplasm nationallicence PCMBS : p-chloromercuribenzenesulfonic acid nationallicence Flora Linda Department of Botany & Plant Sciences, University of California, 92521, Riverside, CA, USA aut Madore Monica Department of Botany & Plant Sciences, University of California, 92521, Riverside, CA, USA aut Planta Springer-Verlag 198/2(1996-02-01), 171-178 0032-0935 198:2<171 1996 198 425 https://doi.org/10.1007/BF00206241 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00206241 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Flora Linda Department of Botany & Plant Sciences, University of California, 92521, Riverside, CA, USA aut NATIONALLICENCE 700 1- Madore Monica Department of Botany & Plant Sciences, University of California, 92521, Riverside, CA, USA aut NATIONALLICENCE 773 0- Planta Springer-Verlag 198/2(1996-02-01), 171-178 0032-0935 198:2<171 1996 198 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer