Project Number: 1910-21000-020-03
Project Type: Specific Cooperative Agreement

Start Date: Sep 07, 2005
End Date: Sep 06, 2007

Objective:
The objective of this cooperative research project is to evaluate the aroma profile of the core accessions and other lines of interest to help define the diversity of this important quality characteristic. Since fruit will be harvested at a specific maturity stage in order to control for stage of development, the fruit will be appropriate for additional assessments related to storability. These include an analysis of the rate of textural change at 0°C in air and assessment of susceptibility to physiological disorders including greasiness, superficial scald, and chilling injury. In addition, this information will be interlaced with an ongoing microarray study to help identify genes regulating aroma volatile biosynthesis, textural shifts, and disorder development. We will also assess the possibility of developing fruit aroma descriptors.

Approach:
The Cooperator (Michigan State University) will collect as much postharvest information about the members of the NPGS, Geneva Malus core collection as is practicable with the primary intent of capturing the diversity of aroma profiles for the collection. To obtain accessions at approximately the same stage of fruit development, fruit maturity will be tracked once per week on fruit sent to MSU via overnight shipments from the NPGS, Geneva. Physiological measures of maturity will include internal ethylene concentration and starch pattern staining. We anticipate as many as 20 accessions, 5 fruit per accession, to be evaluated each week beginning in August 2005. Once it is recognized that the ethylene climacteric is impending or just initiated, we will arrange for the harvest and shipment of sufficient fruit for analysis and storage the following week. For aroma analysis, we intend to hold the fruit so harvested for 7 days at room temperature prior to analysis to allow fruit to fully engage the volatile biosynthetic machinery. For storage analyses, a portion of the fruit will be placed into 0°C refrigerated air storage immediately upon receipt. Fruit texture will be determined initially and once per month for a period of three to 6 months, depending on the rate of deterioration of the fruit. On each analysis date, external fruit quality attributes (e.g., soft scald and superficial scald incidence and severity and greasiness) will be determined. After 2, 4, and 6 months storage, a subset of 10 fruit will be destructively assessed for internal quality defects (e.g., soggy breakdown and senescent breakdown).