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.

3.Progress Report:

This project relates to objective 1 of the associated in-house project which seeks to identify factors that influence postharvest fruit quality and development of market limiting physiological disorders. Storability of apple fruit is ultimately associated with industry profitability and sustainability. Apple fruit ripening behavior closely influences fruit quality including fruit firmness retention during storage, a critical component of consumer acceptance. Ethylene plays an important role in apple fruit development, ripening, and firmness retention, and its biosynthesis and response are modulated by a number of genes. The pattern of expression of these genes during fruit on-tree development and during post-harvest storage was characterized and suggests each has a unique role during on-tree maturation and postharvest ripening. The efficacy of pre- and post-harvest treatments that manipulate ethylene action and ultimately fruit ripening is determined in part by genes expressed at the time of treatment.