Towards QTL analysis of phenological and fruit quality traits in a tetraploid highbush blueberry population

Authors: YALCIN, OZGECAN - Oregon State University; Finn, Chad; Mackey, Theodore - Ted; POTTORF, MARTI - North Carolina State University; IORIZZO, MASSIMO - North Carolina State University; Hardigan, Michael; LUBY, CLAIRE - University Of Wisconsin; Bassil, Nahla

Submitted to: Hortscience Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/5/2021
Publication Date: 9/1/2021
Citation: Yalcin, O., Finn, C.E., Mackey, T.A., Pottorf, M., Iorizzo, M., Hardigan, M.A., Luby, C., Bassil, N.V. 2021. Towards QTL analysis of phenological and fruit quality traits in a tetraploid highbush blueberry population. Abstract for American Society of Horticultural Sciences in August 5-9, 2021, virtual meeting.

Interpretive Summary: Highbush blueberry is a high-value fruit crop that is in increasing demand due to its various health benefits and unique flavor. Marker-assisted breeding (MAB) is becoming a cost-efficient tool for assisting conventional blueberry breeding which can be a long and laborious process. To enable the application of MAB, a statistical analysis called ‘Quantitative Trait Locus (QTL)’ mapping is a necessary first step to identifying the genomic locations of the genes controlling traits of interest. The objective of this study is to phenotype and identify QTLs for 25 fruit quality traits in 196 individuals from a bi-parental family that resulted from a cross between the cultivars ‘Draper’ and ‘Jewel’. In 2020, all progeny were phenotyped for leaf bud, flower bud, flower and fruit development traits as well as a number of fruit quality traits including stem scar size, stem scar tear, wet stem scar, firmness, and weight. Firmness was measured with a texture analyzer at harvest and six weeks after cold storage. A large amount of variation was observed for each trait, indicating segregation for these traits in this family. The phenotypic data is being collected for the same traits in the 2021 season. QTL analysis on these traits will be conducted using a genetic map of the Draper x Jewel population. We anticipate that QTLs generated in this study will facilitate MAB for many of these traits in blueberry.

Technical Abstract: Highbush blueberry (Vaccinium corymbosum L.) is a high-value fruit crop that is in increasing demand due to its various health benefits and unique flavor. Marker-assisted breeding (MAB) is becoming a cost-efficient tool for assisting conventional blueberry breeding which can be a long and laborious process. To enable the application of MAB, Quantitative Trait Locus (QTL) mapping is a necessary first step. The objective of this study is to phenotype and identify QTL for 25 fruit quality traits in 196 individuals from a cross between ‘Draper’ and ‘Jewel’. In 2020, all progeny were phenotyped for leaf bud, flower bud, flower and fruit development traits, as well as a number of fruit quality traits including stem scar size, stem scar tear, wet stem scar, firmness, and weight. Firmness was measured with a texture analyzer at harvest and six weeks after cold storage. A large amount of variation was observed within the population for each trait. The dates for the early green tip stage varied from February 27th through March 26th, and for shoot expansion from February 27th through April 24th. Full bloom was first observed on April 9th through May 29th with a corresponding variation in dates for full ripening from June 26th through August 7th. At harvest, the average single berry weight ranged from 0.3 to 3.3 grams, average firmness ranged from 0.6 to 1.7 N, and stem scar size ranged from 1.6 to 5 mm. For post-harvest, after six-week cold storage, individual berry weight ranged from 0.3 to 2.5 grams, average firmness ranged 0.2 to 1.4 N, and stem scar size ranged 1.3 to 11 mm. Change in weight of 10 berries from each individual after six-week cold storage ranged from -0.97% to -12.7%. Change in firmness between harvest and post-harvest varied from -87% to +24.29% while storage index (SI) ranged from -2.97% to +0.31%, indicating segregation for those traits. The phenotypic data is being collected for the same traits in the 2021 season. QTL analysis on these traits will be conducted using a well-saturated linkage map of Draper x Jewel population using 29,000 SNP markers generated through target capture sequencing. We anticipate that QTL with large effects on a trait that will be identified in this study will be good targets for MAB in blueberry.