Affiliation:
1. Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, USA
Abstract
The decreased profitability of important apple cultivars, such as ‘Honeycrisp’, results from the poor red skin coloration and high fruit drop in the mid-Atlantic US. Apple red skin coloration is determined by the anthocyanin concentration. Reflective groundcovers promote red skin coloration, whereas aminoethoxyvinylglycine (AVG) decreases the ethylene production and fruit drop, thus reducing the coloration. Although our previous study showed that combinations of these practices impact the fruit quality and color, research is lacking regarding their effects at the gene and metabolite levels. In this work, for two years, we compared the differences in the internal ethylene concentration (IEC), red skin coloration, fruit drop, transcript accumulation of key ethylene and anthocyanin biosynthetic pathway-related genes, and total anthocyanin concentration of ‘Honeycrisp’ apples. The fruit was treated with combinations of reflective groundcover (Extenday) and AVG (130 mg L−1) and was assessed throughout ripening. Extenday-only-treated fruit displayed the highest upregulation of ethylene and anthocyanin biosynthetic-related genes and of total anthocyanins, exceeding 50% blush, while boosting the IEC. In contrast, AVG significantly decreased the expression of key ethylene and anthocyanin biosynthetic-related genes and total anthocyanins, thus preventing apples from reaching 50% blush, while also decreasing the IEC and fruit drop. The combination of Extenday x AVG fine-tuned the transcript accumulation of ethylene and anthocyanin biosynthetic-related genes as well as the total anthocyanins, allowing the ‘Honeycrisp’ fruit to exceed 50% blush, while increasing the IEC moderately and reducing the fruit drop (as compared to Extenday-only and control), thus enhancing the fruit economic value.
Funder
State Horticultural Association of Pennsylvania
College of Agriculture and Natural Resources and the Department of Plant Science and Landscape Architecture
Reference88 articles.
1. Isolation and Functional Analysis of a MYB Transcription Factor Gene That Is a Key Regulator for the Development of Red Coloration in Apple Skin;Ban;Plant Cell Physiol.,2007
2. Apple Fruit Quality: Overview on Pre-Harvest Factors;Musacchi;Sci. Hortic.,2018
3. Kon, T.M., and Clavet, C.D. (2023). Enhancing Red Fruit Coloration of Apples in the Southeastern US with Reflective Fabrics. Horticulturae, 9.
4. Miah, M.S., and Farcuh, M. (2024). Combining the Use of Reflective Groundcovers and Aminoethoxyvinylglycine to Assess Effects on Skin Color, Preharvest Drop, and Quality of ‘Honeycrisp’Apples in the Mid-Atlantic US. Horticulturae, 10.
5. USDA Agricultural Marketing Service Apples Grades and Standards (2024, February 11). Available online: https://www.ams.usda.gov/grades-standards/apple-grades-standards.