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Molecular approaches to understanding fruit ripening

 

作者: Colin Brady,  

 

期刊: New Zealand Journal of Crop and Horticultural Science  (Taylor Available online 1992)
卷期: Volume 20, issue 2  

页码: 107-117

 

ISSN:0114-0671

 

年代: 1992

 

DOI:10.1080/01140671.1992.10421903

 

出版商: Taylor & Francis Group

 

关键词: fruit;ripening;mutants;ethylene;respiration;softening enzymes;genes;cDNA;transgenic plants

 

数据来源: Taylor

 

摘要:

The advent of new molecular tools has opened up fresh approaches to some long standing questions concerning the ripening of fruit. These same tools, coupled with transformation and plant regeneration techniques, give promise of the availability of genotypes that may not have been achieved by traditional means. In the latter context, the regulation of ethylene production or perception, colour, disease and insect resistance, and texture have received most emphasis. To have a means of modifying the capacity for ethylene production by a fruit without using inhibitors is an attraction when questions of maturity and ethylene sensitivity are raised. The means may be close at hand. Ethylene production is regulated at two steps: by 1-aminocyclopropane-1-carboxylate reductase, which has a very rapid rate of turnover; and by the ethylene forming enzyme or EFE. Genes for each of these functions have now been located. Also available are some fruit specific promoters and various enhancers. It is already known that down-regulating the EFE gene increases fruit shelf life in tomato, and that exogenous ethylene advances senescence in mutated fruit. The prospect is there to explore the sensitivity of many fruit to exogenous ethylene. There has also been an opportunity to test hypotheses on fruit softening using transgenic tomatoes. A decade or less back, correlation analysis suggested that softening of tomato fruit was regulated by a single factor, the rate of accumulation of the pectin splitting enzyme, endopolygalacturonase. Moreover, the accumulation of the enzyme seemed to depend on contemporaneous gene transcription. So, down-regulation of the gene should inhibit softening, but it did not The hypothesis was disproven and rewoven. Recombinant DNA technology offers other opportunities to explore mechanisms in fruit ripening. Probes for hormone receptors are becoming available and will allow the exploration of the role of receptors in the regulation of maturity and senescence in fruits. Fruit and stage specific promoters offer other opportunities including the further evaluation of the respiratory climacteric that features so prominently in the studies of fruit physiology.

 

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