|BROWN, SUSAN - Cornell University
|ARRO, JIE - Oak Ridge Institute For Science And Education (ORISE)
Submitted to: Tree Genetics and Genomes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2018
Publication Date: 11/12/2018
Citation: Gutierrez, B.L., Zhong, G., Brown, S., Arro, J. 2018. Linkage and association analysis of Dihydrochalcones Phloridzin, Sieboldin, and Trilobatin in Malus. Tree Genetics and Genomes. 14:91. https://doi.org/10.1007/s11295-018-1304-7.
Interpretive Summary: In apple, phloridzin is an important nutritional compound. However, some wild species produce the compounds trilobatin and sieboldin instead of phloridzin, each with unique nutritional properties. Currently, no commercial cultivars contain sieboldin or trilobatin, although, hybrids of cultivated apples with these wild species contain different combinations of these three compounds. Following a germplasm study, populations were developed utilizing unique genetic resources from the USDA-ARS PGRU Malus collection. These populations were screened for dihydrochalcone content using HPLC and genotyped using Genotyping by Sequencing. We identified segregation patterns for the rare dihydrochalcones sieboldin and trilobatin, and identified specific genomics sites associated with their segregation and content variation. These results will lead to greater insight for the genetic and biosynthetic controls of dihydrochalcones in apple. Additionally, molecular markers associated with these compounds could be employed for marker assisted breeding of apple. The information provided through this study will aid in the development of more nutritionally diverse apple cultivars which contain trilobatin and sieboldin, in addition to phloridzin.
Technical Abstract: Dihydrochalcones (DHCs) are a distinctive characteristic of Malus species with phloridzin as the major DHC in most Malus species, including cultivated apple. DHCs in apple have unique chemical properties with commercial and nutritional value, and may yield important insights into the evolution and physiology of apple. A few species produce sieboldin and trilobatin instead of phloridzin, and interspecific hybridization may produce offspring with combinations of phloridzin, sieboldin, and trilobatin. Using Malus prunifolia PI 89816 as a common male parent, five F1 populations were developed to understand the genetic basis of these DHCs in Malus. We measured DHC content in each population and observed segregation into five distinct DHC profiles, which fit a model for three independently segregating loci. QTL associated with DHC content were identified on linkage groups 7 and 8 of the Malus genome using linkage analysis with a cross of NY-152 by M. prunifolia PI 589816 and association mapping with a Malus germplasm collection. In addition to DHC segregation, we observed variation in the relative proportions of phloridzin, sieboldin, and trilobatin when found in combination. The QTL identified represent a critical step in understanding the genetic controllers of DHC content in Malus.