Intracellular sucrose communicates metabolic demand to sucrose transporters in developing pea cotyledons

Zhou, Yuchan, Chan, Katie, Wang, Trevor L., Hedley, Cliff L., Offler, Christina E. and Patrick, John W. (2009) Intracellular sucrose communicates metabolic demand to sucrose transporters in developing pea cotyledons. Journal of Experimental Botany, 60 1: 71-85. doi:10.1093/jxb/ern254


Author Zhou, Yuchan
Chan, Katie
Wang, Trevor L.
Hedley, Cliff L.
Offler, Christina E.
Patrick, John W.
Title Intracellular sucrose communicates metabolic demand to sucrose transporters in developing pea cotyledons
Journal name Journal of Experimental Botany   Check publisher's open access policy
ISSN 0022-0957
1460-2431
Publication date 2009
Year available 2009
Sub-type Article (original research)
DOI 10.1093/jxb/ern254
Open Access Status
Volume 60
Issue 1
Start page 71
End page 85
Total pages 15
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Collection year 2010
Language eng
Subject 1110 Nursing
1314 Physiology
Abstract Mechanistic inter-relationships in sinks between sucrose compartmentation/metabolism and phloem unloading/translocation are poorly understood. Developing grain legume seeds provide tractable experimental systems to explore this question. Metabolic demand by cotyledons is communicated to phloem unloading and ultimately import by sucrose withdrawal from the seed apoplasmic space via a turgor-homeostat mechanism. What is unknown is how metabolic demand is communicated to cotyledon sucrose transporters responsible for withdrawing sucrose from the apoplasmic space. This question was explored here using a pea rugosus mutant (rrRbRb) compromised in starch biosynthesis compared with its wild-type counterpart (RRRbRb). Sucrose influx into cotyledons was found to account for 90% of developmental variations in their absolute growth and hence starch biosynthetic rates. Furthermore, rr and RR cotyledons shared identical response surfaces, indicating that control of transporter activity was likely to be similar for both lines. In this context, sucrose influx was correlated positively with expression of a sucrose/H + symporter (PsSUT1) and negatively with two sucrose facilitators (PsSUF1 and PsSUF4). Sucrose influx exhibited a negative curvilinear relationship with cotyledon concentrations of sucrose and hexoses. In contrast, the impact of intracellular sugars on transporter expression was transporter dependent, with expression of PsSUT1 inhibited, PsSUF1 unaffected, and PsSUF4 enhanced by sugars. Sugar supply to, and sugar concentrations of, RR cotyledons were manipulated using in vitro pod and cotyledon culture. Collectively the results obtained showed that intracellular sucrose was the physiologically active sugar signal that communicated metabolic demand to sucrose influx and this transport function was primarily determined by PsSUT1 regulated at the transcriptional level.
Keyword Cotyledon
Hexose
Pea
Rugosus loci
Seed development
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Queensland Alliance for Agriculture and Food Innovation
 
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Created: Fri, 21 Mar 2014, 14:56:30 EST by Yuchan Zhou on behalf of Qld Alliance for Agriculture and Food Innovation