Changes in ripening-related processes in tomato conditioned by the alc mutant
M Mutschler1, M Guttieri, S Kinzer
1Department of Plant Breeding and Biometry, Cornell University, 14853, Ithaca, NY, USA.
Summary
The alc mutation in tomato fruit impairs ripening and pigment production by reducing specific mRNA levels, including polygalacturonase (PG) mRNA. A spontaneous mutation in Alcobaca-red restores normal ripening, suggesting a trans-acting effect of the alc locus.
Area of Science:
- Plant Biology
- Molecular Genetics
- Fruit Ripening
Background:
- The alc mutation in tomato (Solanum lycopersicum) significantly impacts fruit ripening and storage quality.
- This mutation leads to altered fruit color due to reduced total pigment and altered lycopene content.
- Key enzymatic activities, such as polygalacturonase (PG), and their corresponding protein levels are drastically reduced in alc fruit.
Purpose of the Study:
- To investigate the molecular basis of the alc mutation's effect on tomato fruit ripening.
- To determine the impact of the alc mutation on specific mRNA levels related to fruit ripening.
- To characterize the genetic basis of the Alcobaca-red trait that rescues the alc phenotype.
Main Methods:
- Analysis of pigment content and polygalacturonase (PG) activity in wild-type and alc mutant tomato fruit.
- Quantification of total polyA+ mRNA and hybridization with ripening-related cDNA probes.
- Genetic analysis of the Alcobaca-red trait and chromosomal mapping of ripening-related gene homologs.
Main Results:
- The alc mutation reduces total pigment and lycopene, decreases PG activity and protein to <5% of normal, and alters specific mRNA levels (10-80% reduction).
- PG mRNA levels are severely reduced (5-10% of normal) in alc fruit.
- The Alcobaca-red trait, a spontaneous dominant mutation, rescues the alc phenotype and likely results from a reverse mutation at the alc locus.
- Homologs for 4 out of 5 ripening-related cDNA probes map to chromosomes other than chromosome 10, indicating trans-acting effects of the alc locus.
Conclusions:
- The alc mutation affects tomato fruit ripening through the downregulation of specific ripening-related mRNAs, including PG mRNA.
- The trans-acting nature of the alc locus influences multiple ripening processes.
- The Alcobaca-red line provides a valuable tool for understanding the genetic regulation of tomato fruit ripening and the function of the alc locus.
