Poster: Late and Moved Abstracts
Abs #
1429: Comparative study on gene expression for sucrose cleavage in the storage organs of potato and sweetpotato
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Presenter: |
Li, Xiu-Qing , lixq@agr.gc.ca | Authors | Li, Xiu-Qing (A) Haroon, Muhammad (A) Stevens, Birt (A) Benavides, Jorge (B) Bonierbale, Merideth (B) Zhang, Dapeng (B) | | Affiliations: |
(A): Potato Research Centre, Agriculture and Agri-Food Canada, 850 Lincoln Rd, P.O.Box 20280, Fredericton, New Brunswick, Canada
(B): International Potato Center (CIP), P.O. Box 1558, Lima, Peru
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| Web Site: | http://res2.agr.ca/fredericton/emp/li_e.htm | |
The storage organs that accumulate starch in potato (Solanum tuberosum) and sweetpotato (Ipomoea batatas) are botanically distinct. The storage organ in potato is the tuber, a modified stem; whereas in sweetpotato, it is a modified root, the storage root. It is known that the cleavage of photoassimilated sucrose in storage organs is important for maintaining sink strength. Sucrose metabolism has been investigated considerably in potato, but to a very limited extent in other tuber/root crops. Comparative studies using different crops that have starch-accumulating tubers or roots may reveal common mechanisms for sucrose cleavage and starch accumulation. In the present study, transcriptional activity of genes involved in sucrose cleavage was analyzed using both expressed sequence tag (EST) and RT-PCR approaches. Comparing two potential enzymatic systems--invertase and sucrose synthase--for their roles in cleaving sucrose, the gene expression of sucrose synthase for both potato and sweetpotato was predominant in the enlarging storage organs at which stage a rapid accumulation of starch is expected. In contrast, invertase gene expression was found to be enhanced in cell-formation tissues of sweetpotato plants, which is similar to the literature that invertase activity in potato tubers decreases rapidly during the tuber enlargement after the initiation of tubers. The results suggest that although tuber and root are botanically distinct storage organs, potato and sweetpotato apparently use similar pathway selections in cleaving sucrose and thus potentially also in accumulating starch.
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