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  • Author or Editor: Richard J. Gladon x
  • Journal of the American Society for Horticultural Science x
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Carbon monoxide (CO) is not emanated to any large extent from tomato fruits (Lycopersicon esculentum, Mill. cvs. Rutgers and Ohio MR-13), but is retained within the internal atmosphere. CO is found during all stages of fruit development, but no set pattern of CO concentration is evident.

Open Access

Chlorophyll a and b contents were determined in developing tomato fruit (Lycopersicon esculentum Mill. `Heinz 1350') at 5-day increments from 10 or 15 days past anthesis to fulIy ripe (55 to 60 days). When presented on a whole-fruit basis, chlorophyll a and b contents increased from 15 days past anthesis to 35 days and then decreased to zero at 55 days. Porphobilinogen (EC; PBG) deaminase activity was measured in extracts from the fruit, and changes in PBG deaminase activity correlated with changes in chlorophyll and protein contents with respect to fruit age. Partial characterization of tomato PBG deaminase enzyme showed similarities to PBG deaminase enzymes isolated from other sources.

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Water uptake by impatiens (Impatiens wallerana Hook. f. cv. Super Elfin Coral) seeds was measured as an increase in fresh weight every 24 hours during 144 hours of germination. Seeds absorbed most of the water required for germination within 3 hours of imbibition and germinated at 60% to 67% moisture on a dry-weight basis. Germination started at 48 hours and was complete by 96 hours at 25C. Water stress of -0.1, -0.2, -0.4, and -0.6 MPa, induced by polyethylene glycol 8000, reduced germination by 13%, 49%, 91%, and 100%, respectively, at 96 hours. Under the same water-stress conditions, increases in fresh weight were inhibited by 53%, 89%, 107%, and 106%, respectively. Three distinct groups of storage proteins were present in dry seed; their estimated molecular weights were 1) 35, 33, and 31 kDa; 2) 26, 23, and 21 kDa; and 3) two bands <14 kDa. Major depletion of storage proteins coincided with the completion of germination. Water potentials that inhibited germination also inhibited degradation of storage proteins. During germination under optimum conditions, the soluble protein fraction increased, coinciding with a decrease in the insoluble fraction.

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Activity of 5-aminolevulinic acid (ALA) dehydratase [ALAD, (EC] and soluble protein content were determined in `Rutgers' tomato (Lycopersicon esculentum Mill.) fruit pericarp extracts during development and ripening. ALAD activity in several organs of tomato plant also was determined. Fruit tissue was analyzed at 5-day intervals between days 10 and 60 postanthesis. ALAD activity in fruit tissue declined over time, with the most pronounced decrease occurring between days 10 and 25. At the mature green stage (day 40), and before the breaker stage (day 45), activity of ALAD had declined to a steady-state minimum, and it remained detectable at residual levels throughout ripening (days 40 to 60). Soluble protein content declined less rapidly than did ALAD activity. Immunoblot analysis showed that ALAD protein existed as a doublet of isozymes. One isozyme decreased in abundance, whereas the other isozyme remained constant during development and ripening. ALAD activity was greatest in extracts of chlorophyllous organs (stems, leaves, immature fruit) but only marginally detectable in extracts of nonchlorophyllous organs (roots, overripe fruit). The pH optimum and Km for tomato fruit ALAD were similar to those of ALAD isolated from other sources. Abbreviations: ALA, 5-aminolevulinic acid; ALAD, ALA dehydratase; PBG, porphobilinogen; SDS-PAGE, sodium dodecyl sulfate-polyacry - lamide gel electrophoresis.

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