1a.Objectives (from AD-416)
Characterize the expression patterns of ACS3 genes among elite apple cultivars, and elucidate the relationship of ACS3 expression and effectiveness of MCP treatment as well as subsequent postharvest fruit quality.
1b.Approach (from AD-416)
1. Fruit tissues representing different developmental stages will be collected for 12-16 cultivars, starting 30 days after full bloom till commercial maturity. 2. Apple fruits harvested at commercial maturity will be treated with1-MCP and fruit firmness changes of stored fruit will be assessed for at least 3 months. 3. Total RNAs will be isolated from above-mentioned fruit tissues using established procedure. 4. Gene-specific primers will be utilized to examine the expression patterns and dynamics on major ethylene biosynthesis enzyme encoding genes by quantitative real-time PCR methodology. Documents Trust with Agrofresh. Log 36996.
This project is related to objective 2 of the associated in-house project which is to identify the genetic factors regulating fruit texture. Understanding the genetic control of ethylene, the natural signal that regulates apple fruit ripening, will facilitate the development of tools to enhance apple breeding as well as postharvest fruit quality management. Ethylene’s role in regulating fruit ripening and quality is indisputable. A major ethylene biosynthesis gene, MdACS1, has been well characterized, but little is known regarding the role of MdACS3, another ethylene biosynthesis gene that is expressed prior to the onset of ripening. ARS scientists at the Tree Fruit Research Laboratory used 15 apple cultivars to evaluate ripening and ethylene production at harvest and after cold storage. The results indicated two different expression patterns of MdACS3 among these cultivars, and these expression in general correlates with ripening season and fruit storability. For example, ‘Granny Smith’, ‘Jazz’ and ‘Pink Lady’, which are generally store well and respond well to the ethylene inhibitor 1-MCP, have low MdACS3 expression. ‘Golden Delicious’, ‘McIntosh’, and ‘Honeycrisp’ showed high MdACS3 expression at harvest and normally don’t respond as well to 1-MCP. The results have been summarized in a manuscript and submitted to a peer reviewed journal. Additional work on the role of MdACS3 expression and its relationship to apple postharvest quality is underway.
Progress is monitored through annual submission of written and oral progress reports to the funding agency.