The CO2 and C2H4 conc in the internal cavity of three melon (Cucumis melo L., var. reticulatus and inodorus Naud.) cultivars was periodically measured in fruit attached to the vine and in fruit harvested 30 days after pollination (DAP). Gas samples were withdrawn through sterile serum stopper sampling ports aseptically installed near the equator of each fruit at ca. 20 DAP. Sampling continued until either 60 DAP or until fruit abscised. Internal CO2 and C2H4 conc increased in harvested fruit as they ripened (i.e., increased percent soluble solids, decreased flesh firmness, characteristic external color change). Fruit allowed to ripen on the vine also exhibited a rise in C2H4, but lacked a ripening associated climacteric rise in respiration, CO2 conc in attached fruit remained constant or declined as the C2H4, conc increased around 40-fold and the fruit ripened. The increase in CO2 conc, so commonly observed in ripening climacteric fruit, was observed in harvested melons, but not in fruit ripening on the vine. In melons, the respiratory climacteric may be an artifact of harvest. Implications of these observations will be discussed.
Krista C. Shellie and Mikal E. Saltveit Jr.
Respiration (i.e., carbon dioxide production and oxygen consumption) increases as ripening is initiated in a group of harvested fruit called climacteric. This group includes many horticulturally important fruit crops, such as apples, avocados, bananas, melons, peaches, pears, and tomatoes. Other fruit, which includes cherries, citrus, and strawberries, do not exhibit an increase in respiration as they ripen and are called nonclimacteric. Measurements of carbon dioxide production by ripening apples, melons, and tomatoes revealed a well-defined climacteric, but only in harvested fruit. The respiratory climacteric was greatly diminished or absent from these fruit when they ripened while attached to the plant. Fixation of respired carbon dioxide through photosynthesis or into organic acids was insufficient to account for the diminished amount of carbon dioxide evolved from ripening attached climacteric fruit. Unlike the respiratory climacteric, an increase in ethylene production occurred in both attached and harvested climacteric fruit. Ethylene stimulates respiration in most plant tissues. The rapid rise in respiration as soon as attached ripening climacteric fruit were harvested or abscised suggests that an inhibitor of ethylene-stimulated respiration may be translocated from the plant and prevent the climacteric rise in respiration in attached ripening fruit.
Guihua Lu, Chengde Yang, Houguo Liang, and Zhongshu Lu
Oscar Andrés Del Angel-Coronel, Juan Guillermo Cruz-Castillo, Javier De La Cruz-Medina, and Franco Famiani
respiratory burst (termed the respiratory climacteric) and pronounced ethylene synthesis during ripening, whereas nonclimateric fruits do not show such increases ( Kader, 2002 ; Tucker, 1993 ). In climacteric fruits, the peak can correspond to optimum eating
Zhen Shu, Yimin Shi, Hongmei Qian, Yiwei Tao, and Dongqin Tang
physiological metabolism was broken with the senescence progression in Freesia flowers. Respiratory climacteric, rapid loss of soluble compounds, decrease of antioxidative enzymes activities, increases of MDA content, and EL could be considered the indicators
Marisa M. Wall
313 320 Hubbard, N.L. Pharr, D.M. Huber, S.C. 1990 Role of sucrose phosphate synthase in sucrose biosynthesis in ripening bananas and its relationship to the respiratory climacteric Plant Physiol. 94 201
Nobuko Sugimoto, Steve van Nocker, Schuyler Korban, and Randy Beaudry
A microarray containing over 10,000 gene fragments was used to link changes in gene expression with changes in aroma biosynthesis in ripening apple (Malus ×domestica Borkh). The microarray was probed with fluorescent-tagged cDNA derived from RNA extracted from `Jonagold' apple skin and cortex tissue representing eight distinct physiological stages spanning 70 days during ripening and senescence. The ripening stages, in chronological order, were: 1) early preclimacteric; 2) late preclimacteric and onset of trace ester biosynthesis; 3) onset of the autocatalytic ethylene and rapidly increasing ester biosynthesis; 4) half-maximal ester biosynthesis and engagement of the respiratory climacteric; 5) near maximal ester biosynthesis, peak in respiratory activity, and the onset of rapid tissue softening; 6) maximal ester biosynthesis prior to its decline, the conclusion of the respiratory climacteric, and the completion of tissue softening; 7) midpoint in the decline in ester biosynthesis and maximal ethylene biosynthesis; and 8) postclimacteric minimum in ester production. Patterns in gene expression reflecting the rise and fall in ester formation were found in some putative genes for beta-oxidation (acyl-CoA oxidase, enoyl-CoA hydratase, and acetyl-CoA acetyl transferase), ester formation (aminotransferase, alcohol dehydrogenase, and alcohol acyl transferase), and fatty acid oxidation (lipoxygenase), but not fatty acid biosynthetic genes. A marked decline coinciding with the onset of ester production was detected in several putative genes for ADH.
Steven A. Altman and Theophanes Solomos
Sim-type carnation flowers (Dianthus caryophyllus L., cv. Elliot's White) continuously treated with 50 mM or 100 mM 3-amino-1,2,4-triazole (amitrole) and held in the dark at 18°C did not exhibit a respiratory climacteric relative to dH2O-treated controls. No morphological changes symptomatic of floral senescence appeared in treated flowers until 12-15 days post-harvest. Other triazoles were not effective in prolonging senescence. Amitrole appears to inhibit ethylene biosynthesis by blocking the enzyme-mediated conversion of S-adenosyl-L-methionine to 1-aminocyclopropane-1-carboxylate. Ethylene action appears to be progressively inhibited in that flowers held in treatment solution for 2 d or less responded to application of 10 uL/L exogenous ethylene whereas flowers held 10 d or longer exhibited no response. Electrophoretic resolution of total crude extracts evidenced protein synthesis as well as degradation. Western analysis and total activity assays showed an amitrole concentration-specific inhibition of catalase activity.
Steven A. Altman and Theophanes Solomos
Continuous postharvest treatment of carnation flowers (Dianthus caryophyllus L. cv. Elliot's White) with 50 or 100 mM aminotriazole significantly extended useful vase life relative to flowers held in distilled H2O. No morphological changes symptomatic of floral senescence appeared in treated flowers until 12 to 15 days after harvest. The longevity of aminotriazole-treated flowers was extended to ≈18 days. The respiratory rate of aminotriazole-treated carnations was suppressed, and they exhibited no respiratory climacteric throughout the period of observation. The responsiveness of aminotriazole-treated flowers to exogenous ethylene appeared temporally regulated. Flowers treated with 50 mM aminotriazole for 2 days senesced in response to application of 10 μl exogenous ethylene/liter, whereas flowers treated for 24 days exhibited no morphological response to ethylene treatment. Chemical name used: 3-1H-amino-1,2,4-triazole-1-yl (aminotriazole).
Ernesto A. Brovelli, Jeffrey K. Brecht, Wayne B. Sherman, and Charles A. Sims
The notion that ethylene production levels in nonmelting-flesh (NMF) peach (Prunus persica L.) fruit are normally lower than those in melting-flesh (MF) fruit is refuted in our study. In fact, NMF fruit (`Oro A' and FL 86-28C) usually produced higher levels of ethylene than did MF fruit (FL 90-20 and `TropicBeauty'). In both MF and NMF peaches, the rate of ethylene production, rather than the respiration rate, provided a good indication of the developmental stage of the fruit at harvest. Ethylene content in fruit on the tree followed a climacteric pattern, with the level in `Oro A' (NMF) and FL 90-20 (MF) peaking at 50 and 12 μL·L–1, respectively. The respiratory climacteric was not apparent in either `Oro A' or FL 90-20, and levels of CO2 were similar in both genotypes.