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Title: Manipulation of sucrose phloem and embryo loading affects pea leaf metabolism, carbon and nitrogen partitioning to sinks as well as seed storage pools
Summary

Seed development largely depends on the long‐distance transport of sucrose from photosynthetically active source leaves to seed sinks. This source‐to‐sink carbon allocation occurs in the phloem and requires the loading of sucrose into the leaf phloem and, at the sink end, its import into the growing embryo. Both tasks are achieved through the function ofSUTsucrose transporters. In this study, we used vegetable peas (Pisum sativumL.), harvested for human consumption as immature seeds, as our model crop and simultaneously overexpressed the endogenousSUT1transporter in the leaf phloem and in cotyledon epidermal cells where import into the embryo occurs. Using this ‘Push‐and‐Pull’ approach, the transgenicSUT1plants displayed increased sucrose phloem loading and carbon movement from source to sink causing higher sucrose levels in developing pea seeds. The enhanced sucrose partitioning further led to improved photosynthesis rates, increased leaf nitrogen assimilation, and enhanced source‐to‐sink transport of amino acids. Embryo loading with amino acids was also increased inSUT1‐overexpressors resulting in higher protein levels in immature seeds. Further, transgenic plants grown until desiccation produced more seed protein and starch, as well as higher seed yields than the wild‐type plants. Together, the results demonstrate that theSUT1‐overexpressing plants with enhanced sucrose allocation to sinks adjust leaf carbon and nitrogen metabolism, and amino acid partitioning in order to accommodate the increased assimilate demand of growing seeds. We further provide evidence that the combined Pushand‐Pull approach for enhancing carbon transport is a successful strategy for improving seed yields and nutritional quality in legumes.

 
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NSF-PAR ID:
10458536
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
The Plant Journal
Volume:
101
Issue:
1
ISSN:
0960-7412
Page Range / eLocation ID:
p. 217-236
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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