An ethylene-related cDNA from ripening apples

Area of Science:

• Plant Molecular Biology
• Fruit Ripening Biochemistry
• Ethylene Signaling Pathways

Background:

• Ethylene is a key plant hormone regulating fruit ripening.
• Understanding ethylene biosynthesis is crucial for controlling fruit quality.
• Previous research identified ethylene-related genes in tomato and avocado.

Purpose of the Study:

• To isolate and characterize an apple cDNA clone potentially involved in ethylene production.
• To investigate the expression patterns of this clone during apple fruit ripening.

Main Methods:

• Construction of a cDNA library from ripe 'Golden Delicious' apple fruit cortical tissue.
• Screening the library using a tomato ACC oxidase cDNA clone (pTOM13).
• Sequencing of the isolated apple cDNA clone (pAP4) and analysis of its homology and predicted protein characteristics.

Main Results:

• Isolation and sequencing of an apple cDNA clone, pAP4 (1182 bp), with a 942 bp open reading frame.
• pAP4 shows significant nucleic acid and amino acid homology to tomato and avocado ACC oxidase sequences.
• Expression of pAP4-complementary RNA increased in apple cortical tissue during ripening, correlating with ethylene production.
• Expression was further enhanced by exogenous ethylene treatment and wounding.

Conclusions:

• The isolated apple cDNA clone, pAP4, likely codes for an ACC oxidase involved in ethylene biosynthesis during fruit ripening.
• pAP4 expression is regulated by ethylene and mechanical stress, highlighting its role in fruit development and response.
• This finding provides a molecular tool for further research into apple fruit ripening and ethylene regulation.