Carbon Translocation in the Tomato: Pathways of Carbon Metabolism in the Fruit- |
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Authors: | WALKER A J; HO L C; BAKER D A |
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Institution: | Glasshouse Crops Research Institute Uttlehampton, Sussex, BN16 3PU
School of Biological Sciences, University of Sussex Brighton, Sussex, BN1 9QG |
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Abstract: | The rate of carbon import by tomato fruits has been relatedto their carbon metabolism by examining the effects of fruittemperature on the metabolism of imported assimilates. 14Csucrose,glucose, fructose, malic acid and citricacid were injected individually into young growing tomato fruitswhich were subsequently maintained at 25 or 5 °C for 48h. Fruit temperature greatly affected the proportions of 14Clost from the fruits by export and respiration. Only 40 percent of the injected 14C from 14Csugars and 20 per centfrom 14Cacids was recovered from fruits at 25 °C.Less than 10 per cent of the injected 14C was exported, thebalance being respired. In contrast, more than 50 per cent ofthe injected 14C was recovered from cooled fruits, in whichthe import rate of carbon was presumably reduced, and 2036per cent of injected 14C was exported. Cooling enhanced thesynthesis of 14Csucrose from injected 14Chexosesand inhibited the incorporation of 14C into starch and insolubleresidue. When 14Csugars were injected, radioactivityexported from the cooled fruits was detected as sucrose in thephloem of the peduncles; radioactivity was also detected instems and roots when fruits were cooled. In almost fullygrownfruits injected 14Ccompounds were metabolized less readilythan in smaller fruits. Conversion of 14Chexoses to 14Csucrosewas again enhanced by cooling (5 °C, but was less in fruitsmaintained at 35 °C than in controls. Lycopersicon esculentum, tomato, fruit, translocation, carbon metabolism |
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