Header

UZH-Logo

Maintenance Infos

Identification of Sorbitol Transporters Expressed in the Phloem of Apple Source Leaves


Watari, Junya; Kobae, Yoshihiro; Yamaki, Shohei; Yamada, Kunio; Toyofuku, Kyoko; Tabuchi, Toshihito; Shiratake, Katsuhiro (2004). Identification of Sorbitol Transporters Expressed in the Phloem of Apple Source Leaves. Plant & Cell Physiology, 45(8):1032-1041.

Abstract

Sorbitol is a major photosynthetic product and a major phloem-translocated component in Rosaceae (e.g. apple, pear, peach, and cherry). We isolated the three cDNAs, MdSOT3, MdSOT4, and MdSOT5 from apple (Malus domestica) source leaves, which are homologous to plant polyol transporters. Yeasts transformed with the MdSOTs took up sorbitol significantly. MdSOT3- and MdSOT5-dependent sorbitol uptake was strongly inhibited by xylitol and myo-inositol, but not or only weakly by mannitol and dulcitol. Apparent Km values of MdSOT3 and MdSOT5 for sorbitol were estimated to be 0.71mM and 3.2mM, respectively. The protonophore, carbonyl cyanide m-chlorophenylhydrazone (CCCP), strongly inhibited the sorbitol transport. MdSOT3 was expressed specifically in source leaves, whereas MdSOT4 and MdSOT5 were expressed in source leaves and also in some sink organs. MdSOT4 and MdSOT5 expressions were highest in flowers. Fruits showed no or only weak MdSOT expression. Although MdSOT4 and MdSOT5 were also expressed in immature leaves, MdSOT expressions increased with leaf maturation. In addition, in situ hybridization revealed that all MdSOTs were expressed to high levels in phloem of minor veins in source leaves. These results suggest that these MdSOTs are involved in sorbitol loading in Rosaceae

Abstract

Sorbitol is a major photosynthetic product and a major phloem-translocated component in Rosaceae (e.g. apple, pear, peach, and cherry). We isolated the three cDNAs, MdSOT3, MdSOT4, and MdSOT5 from apple (Malus domestica) source leaves, which are homologous to plant polyol transporters. Yeasts transformed with the MdSOTs took up sorbitol significantly. MdSOT3- and MdSOT5-dependent sorbitol uptake was strongly inhibited by xylitol and myo-inositol, but not or only weakly by mannitol and dulcitol. Apparent Km values of MdSOT3 and MdSOT5 for sorbitol were estimated to be 0.71mM and 3.2mM, respectively. The protonophore, carbonyl cyanide m-chlorophenylhydrazone (CCCP), strongly inhibited the sorbitol transport. MdSOT3 was expressed specifically in source leaves, whereas MdSOT4 and MdSOT5 were expressed in source leaves and also in some sink organs. MdSOT4 and MdSOT5 expressions were highest in flowers. Fruits showed no or only weak MdSOT expression. Although MdSOT4 and MdSOT5 were also expressed in immature leaves, MdSOT expressions increased with leaf maturation. In addition, in situ hybridization revealed that all MdSOTs were expressed to high levels in phloem of minor veins in source leaves. These results suggest that these MdSOTs are involved in sorbitol loading in Rosaceae

Statistics

Citations

Dimensions.ai Metrics
67 citations in Web of Science®
77 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

23 downloads since deposited on 19 Oct 2018
10 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:National licences > 142-005
Dewey Decimal Classification:580 Plants (Botany)
570 Life sciences; biology
590 Animals (Zoology)
Scopus Subject Areas:Life Sciences > Physiology
Life Sciences > Plant Science
Life Sciences > Cell Biology
Language:English
Date:15 August 2004
Deposited On:19 Oct 2018 07:04
Last Modified:15 Apr 2021 14:50
Publisher:Oxford University Press
ISSN:0032-0781
OA Status:Hybrid
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1093/pcp/pch121

Download

Hybrid Open Access

Download PDF  'Identification of Sorbitol Transporters Expressed in the Phloem of Apple Source Leaves'.
Preview
Content: Published Version
Language: English
Filetype: PDF (Nationallizenz 142-005)
Size: 1MB
View at publisher