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Use of a tomato mutant constructed with reverse genetics to study fruit ripening, a complex developmental process
A Theologis1, P W Oeller, L M Wong
1Plant Gene Expression Center, Albany, California 94710.
Developmental Genetics
|January 1, 1993
Summary
Tomato fruit ripening involves ethylene, a plant hormone. Suppressing ethylene production significantly inhibits ripening, suggesting distinct developmental and ethylene-dependent pathways regulate gene expression and protein translation during this process.
Area of Science:
- Plant Biology
- Molecular Biology
- Biochemistry
Background:
- Fruit ripening is a complex developmental process involving significant gene expression changes.
- Ethylene (C2H4) is widely recognized as a key plant hormone regulating fruit ripening.
Purpose of the Study:
- To investigate the role of 1-aminocyclopropane-1-carboxylate (ACC) synthase in ethylene biosynthesis and its impact on tomato fruit ripening.
- To elucidate the distinct signaling pathways involved in tomato fruit ripening.
Main Methods:
- Constructed transgenic tomato plants expressing antisense or sense RNA for ACC synthase using CaMV 35S and E8 promoters.
- Quantified ethylene production, analyzed mRNA accumulation (PG, ACC oxidase, E8, E17, J49, D2), and assessed protein expression (PG) in transgenic fruits.
- Utilized propylene (C3H6) treatment to assess gene and protein restoration.
Main Results:
- Severe suppression (>99%) of ethylene production in antisense LE-ACS2 RNA fruits prevented ripening.
- Antisense fruits accumulated mRNAs for ethylene-inducible genes but showed inhibited E4 expression and failed PG protein translation.
- Propylene treatment restored PG protein accumulation in antisense fruits, indicating post-transcriptional regulation.
Conclusions:
- Tomato fruit ripening involves at least two independent signal transduction pathways: a developmental pathway and an ethylene-dependent pathway.
- The developmental pathway controls the transcriptional activation of ripening-related genes.
- The ethylene-dependent pathway regulates gene expression, lycopene and aroma biosynthesis, and the translation of developmentally regulated genes like PG.