Analysis of a Multi-Environment Trial for Black Raspberry (Rubus occidentalis L.) Quality Traits.

Matthew R Willman,Courtney A Weber,Jill M Bushakra,Joseph C Scheerens,Christine M Bradish,Jonathan Fresnedo-Ramírez,Chad E Finn,Gina E Fernandez,Nahla Bassil,Michael Dossett,Lisa Dunlap,Penelope Perkins-Veazie

doi:10.3390/genes13030418

Abstract

U.S. black raspberry (BR) production is currently limited by narrowly adapted, elite germplasm. An improved understanding of genetic control and the stability of pomological traits will inform the development of improved BR germplasm and cultivars. To this end, the analysis of a multiple-environment trial of a BR mapping population derived from a cross that combines wild ancestors introgressed with commercial cultivars on both sides of its pedigree has provided insights into genetic variation, genotype-by-environment interactions, quantitative trait loci (QTL), and QTL-by-environment interactions (QEI) of fruit quality traits among diverse field environments. The genetic components and stability of four fruit size traits and six fruit biochemistry traits were characterized in this mapping population following their evaluation over three years at four distinct locations representative of current U.S. BR production. This revealed relatively stable genetic control of the four fruit size traits across the tested production environments and less stable genetic control of the fruit biochemistry traits. Of the fifteen total QTL, eleven exhibited significant QEI. Closely overlapping QTL revealed the linkage of several fruit size traits: fruit mass, drupelet count, and seed fraction. These and related findings are expected to guide further genetic characterization of BR fruit quality, management of breeding germplasm, and development of improved BR cultivars for U.S. production.

Highlights

Black raspberry (Rubus occidentalis L.) is a high-value yet minor crop cultivated in theU.S for both fresh and processing markets
The six ORUS 4305 identified in this study as off-types match those reported by Bushakra et al [22] as having incongruous Single-nucleotide polymorphisms (SNPs) data, and they were removed from linkage map construction in the cited study
It was not possible to produce linkage map information for ORUS 4304, the quantitative trait loci (QTL) analysis performed for ORUS 4305 enabled the elucidation of genetic components contributing to fruit size and seediness, which were found to be highly heritable and fairly stable across environments

Summary

Introduction

Black raspberry (Rubus occidentalis L.) is a high-value yet minor crop cultivated in theU.S for both fresh and processing markets. Black raspberry (Rubus occidentalis L.) is a high-value yet minor crop cultivated in the. North America, where it is enjoyed both as wild forage and in commercially cultivated varieties. To date, it is commercially grown as a specialty crop in the Midwest, Northeast, and Northwest regions of the U.S There is active interest in expanding BR production into the southern U.S [1]. Breeding to improve adaptation and other commercial traits, the trend among consumers is a preference for European red raspberry fruit [2]. BR fruit tend to be small and seedy, whereas fresh fruit consumers prefer large fruit with smaller seeds (C.E. Finn, personal observation). Breeding attempts to increase BR fruit size have historically been met with limited success [4,5,6], limiting the availability of diverse productive cultivars to growers [7,8]

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