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Abstract Detail


Salinity

Loescher, Wayne [1], Sabbatini, Paolo [2], Song, Guo-Qing [2], Sink, Ken [2], Flore, James [2].

Anti-sensing acyclic polyol (mannitol) biosynthesis in celery decreases salt tolerance.

Mannitol, a sugar alcohol that may serve as an osmoprotectant or compatible solute, is a major photosynthetic product in celery (Apium graveolens L.) where it is synthesized via a NADPH dependent mannose-6-phosphate reductase (M6PR). Cytosolic localization of M6PR was indicated by cellular fractionation, and confirmed by immunocytochemistry, work that also indicated that M6PR occurs primarily in leaf mesophyll cells. Arabidopsis plants transgenic for M6PR have since been shown to be salt tolerant. To confirm the abiotic stress effects of mannitol biosynthesis, we have transformed celery with an antisense construct of the celery leaf M6PR gene under control of the CaMV 35S promoter. Unlike wild type (WT) celery, independent antisense M6PR transformants did not accumulate significant amounts of mannitol in any tissue, with or without salt stress. In the absence of NaCl, and despite the lack of any significant accumulation of mannitol as the normally major photosynthetic product, antisense transformants were phenotypically and photosynthetically quite similar to the WT celery. However, in the presence of NaCl, mature antisense transgenic plants were significantly less salt tolerant, with reduced growth and photosynthetic rates, and some transformants were killed at 200 mM NaCl, a concentration that WT celery can ordinarily withstand. Although mannitol biosynthesis is enhanced in salt-treated WT celery, no such increase was observed in the anti-sense transformants. Like our previous ‘gain of function’ results showing enhanced salt tolerance in Arabidopsis plants transgenic for a sense M6PR construct, these ‘loss of function’ results in celery, with an antisense construct, demonstrate a major role for mannitol biosynthesis in developing salt tolerant plants.


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1 - Michigan State University, Horticulture, 328 Plant and Soil Sciences, East Lansing, MI, 48824-1325, United States
2 - Michigan State University, Horticulture

Keywords:
salinity
mannitol
Photosynthesis
transgenic
antisense.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P07010
Abstract ID:1151


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