Program Areas — Dr. Amy Iezzoni , Professor
Plant Breeding and Genetics
Sour Cherry Breeding
The sour cherry (Prunus cerasus) industry in the U.S. is a monoculture of a 400-year-old variety from France called Montmorency. The goals of the MSU sour cherry breeding program are to develop new cultivars which will have superior fruit quality and disease resistance compared to Montmorency, and will yield consistently over years. To reach these goals, we have an aggressive breeding program which includes approximately 25 acres of seedlings and 15 test sites around the U.S. Currently our disease resistance breeding program involves the introgression of resistance gene(s) for cherry leaf spot (Blumeriella jaapii) resistance from wild Prunus species, P. canescens and P. maackii, into commercially acceptable sour cherry cultivars. The first release from the breeding program, named Balaton®, originated as a landrace variety from Hungary.
Cherry Genetics
Self-incompatibility: The diploid sweet cherry is a classic example of a species exhibiting S-RNase-based gametophytic self-incompatibility. In comparison, individual tetraploid sour cherry selections can be either self-compatible or self-incompatible. Our goal is to understand the genetic control of self-compatibility and self-incompatibility in sour cherry. Our current hypothesis is that self-compatibility arose in sour cherry from the more ancestral state of self-incompatibility due to the occurrence of self-fertile mutants. So far one of these self-fertile mutants has been characterized as having an insertion in the putative promoter region of the S6-RNase.
Fruit Quality Traits: We have a long standing interest in the genetic control of fruit quality traits in both sweet and sour cherry. Our research strategy is to identify QTLs that control fruit quality traits that have been altered during domestication. For this analysis over 900 progeny were generated from the cross between a wild sweet cherry with small highly acid dark fruit and a domesticated variety with large pink sweet fruit.
Our initial focus is on the genetic control of fruit size. Anatomical studies indicate that the fruit of NY 54 is larger than the fruit of Emperor Francis solely due to an increase in cell number, not cell size. Research is ongoing to understand the genetic control and timing of this difference in cell number.
Bloom time: One out of every three years, cherry yields in Michigan are significantly reduced by spring freeze damage. We are currently using a QTL strategy in a sour cherry population that exhibits extensive transgressive segregation for late bloom time, to identify the genomic region(s) that control bloom time. Our long term goal is to fine-map QTL regions identified as a prelude to candidate gene analysis.
Sweet cherry rootstock selection
The breeding program has an ongoing effort to identify precocious dwarfing rootstocks for sweet cherry from the MSU cherry germplasm collection. So far, 93 MSU rootstock selections are under test in replicated trials in Michigan and Washington State with Hedelfingen and Bing scions, respectively.
Dr. Amy Iezzoni
Professor
A342 Plant & Soil Science Building
East Lansing, MI 48824-1325
Phone: (517) 355-5191 x 1391
Fax: (517) 353-0890
Email: iezzoni@msu.edu