2006 Fiscal Year Final Research Report Summary
The mechanism for the determination of soluble sugar content of fruits
| Project/Area Number |
15380023
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Horticulture/Landscape architecture
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KAWABATA Saneyuki The University of Tokyo, Graduate School of Agricultural and Life Sciences, Associate Professor (10234113)
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| Project Period (FY) |
2003 – 2006
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| Keywords | tomato / source-sink ratio / phloem sap / soluble solid content / translocation / callose / microarray / transpiration / 蒸散 |
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| Research Abstract |
The translocation of photosynthates from source to sink organs involves the delivery of sugars by water flow through the phloem. It has been found that more than 90% of water that enter fruits is delivered through the phloem, while only a small portion of water is through the xylem. This finding suggests that solid content of fruits, which should highly correlates to a ratio of sugar transport to water transport into fruits, would be determined by the sugar concentration of the phloem sap.
In this study, we attempted to develop a method to determine the sugar concentration of the phloem sap in tomato. This method is based on the inhibition of callose formation by Ca chelation in EDTA solution. The pedicel was excised and the cut end was incubated in EDTA solution containing cell membrane impermeable fluorescent probe, HPTS. The volume of the exudates was calculated by using the dilution rate of HPTS. The volume of the phloem exudate was determined as the exudation reduction by heat girdling on the pedicel.
By this method, we could collect 0-50μL of phloem sap, and sucrose concentration of phloem sap could be determined. However, the collection was sometimes unsuccessful depending on plant conditions. In contrast, we could successfully collect xylem sap and could determine its calcium concentration. Since calcium is mainly transported through the xylem, total transport of water through the xylem could be estimated, and then water flow through the phloem and the sugar. concentration of the phloem sap could be determined accordingly. In experiments where tomato plants with different source/sink ratios were used, the sucrose concentration of the phloem sap showed a high correlation to the solid content of the fruits. The results indicated a high contribution of the phloem in total water transport into fruits.
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Research Products
(8 results)
