Interest in off-season production of red raspberry ( Rubus idaeus L.) is increasing as a result of the high demand for a limited supply ( Darnell et al., 2006 ; Knight et al., 1996 ; Pritts et al., 1999 ; Schloemann, 2001 ) and the resultant
Horacio E. Alvarado-Raya, Rebecca L. Darnell, and Jeffrey G. Williamson
Justine E. Vanden Heuvel and Kimberly Lewers
programs? The articles published here provide information on breeding, producing, and marketing repeat-fruiting small fruit crops using day-neutral strawberry, primocane-fruiting blackberry, and primocane-fruiting raspberry as examples.
Shengrui Yao and Carl J. Rosen
harvested for primocane-fruiting raspberries. In warm years with later killing frosts, growers can expect to have a reasonable crop of fall raspberries; but in other years, growers might have a minimal crop or none at all (D. Wildung, personal communication
M. Joseph Stephens, Jessica Scalzo, Peter A. Alspach, Ron A. Beatson, and Ann Marie Connor
favored in some red raspberry breeding programs involves yield estimates ( Daubeny et al., 1986 ). Fruit yield can be broken down to several component parts, and accuracy of the yield estimates may be influenced by which components are taken into
P.G. Braun, P.D. Hildebrand, and A.R. Jamieson
Twenty-five cultivars of red raspberry (Rubus idaeus L.) and one purple raspberry (R. occidentalis L. × R. idaeus L.) were evaluated for their resistance to fire blight caused by Erwinia amylovora (Burr.) Winslow et al. Actively growing raspberry cane tips were wound inoculated with three isolates of the pathogen and disease development was assessed over 17 days. Three methods of evaluating resistance were used: area under the disease progress curve (AUDPC), a weighted AUDPC called the area under the disease severity curve (AUDSC), and lesion length. A wide range of resistance levels was observed, but no cultivars were symptomless. Primocane-fruiting cultivars tended to be more resistant than floricane-fruiting ones. Of the three E. amylovora isolates used in this study, one was significantly more virulent than the other two, but no cultivar × isolate interaction was detected.
Penelope Perkins-Veazie and Gail Nonnecke
Raspberry (Rubus idaeus L., `Heritage') fruit were harvested at six stages of color development to determine the relationship between quality attributes and physiological changes during ripening. Soluble solids concentration and fruit weight increased, whereas titratable acidity decreased during ripening. Fruit darkened and color saturation increased with maturity. Raspberry fruit exhibited a nonclimacteric pattern of respiration, and ethylene (C2H4) was detected only after red pigment developed. Respiration and C2H4 production of whole fruit were similar to those of drupes. Ethylene-forming enzyme activity commenced in drupes and receptacle tissue from fruit at the yellow and mottled stages, respectively. These data indicate that ripening in raspberry fruit is independent of C2H4 production and is nonclimacteric.
Courtney A. Weber and William Boone
The role of plant pigments in human health has been under intense scrutiny recently. Anthocyanin pigments have been shown to be powerful antioxidants and may contribute to other areas of human health. In red and black raspberry, Rubus idaeus and Rubus occidentalis, respectively, no less than eight different anthocyanin pigments have been identified. However, the genetics controlling the presence and ratios of the different pigments is poorly understood. Various researchers have identified four loci that impart fruit pigment deficiencies and three loci that affect the pigment ratios. The underlying gene function of these loci is not known. Efforts are under way to map two pigment deficiency loci in red raspberry using bulked segregant analysis. Screening with 800 random primers has produced two markers with >90% and two with >80% correlation to one loci. For the other loci, 10 markers with >80% correlation have been identified. Mapping is ongoing with the first linkage map for raspberry to be presented. Populations to test allelism between sources of pigment deficiency are being evaluated for further mapping of loci of the anthocyanin production pathway. Data on cloning of genes in the anthocyanin pathway based on database sequences with degenerative primers for further elucidation a anthocyanin production in raspberry will be presented.
Rachel E. Rudolph, Lisa W. DeVetter, Inga A. Zasada, and Cedar Hesse
In 2017, approximately 35,600 t of raspberry ( Rubus idaeus L.) were produced in Washington and Oregon and valued at over $57 million ( U.S. Department of Agriculture, 2019 ). Washington leads the United States in the production of red raspberry
Lack of variation among black raspberry cultivars is thought to be a limiting factor in fruit production and in breeding improved cultivars. An assessment of the available diversity in black raspberry is needed to effectively develop improved cultivars. Such an assessment was done to estimate the genetic similarities for RAPD markers in 16 black raspberry genotypes and to determine the genetic diversity among these genotypes based on these markers. In addition, the ability to distinguish between the black raspberry genotypes, two red raspberry cultivars (Rubus idaeus L.), and a blackberry cultivar (Rubus hybrid) was determined. A similarity matrix from 379 RAPD markers was calculated, and a phylogenetic tree was constructed using the PHYLIP suite of phylogeny software, which revealed the relationship among the genotypes. An average of 81% similarity was calculated among 16 black raspberry genotypes with a maximum similarity of 98% and a minimum of 70%. The average similarity between black raspberry and red raspberry was 41% and was 26% between black raspberry and blackberry. Combined marker profiles from six RAPD primers could be used to distinguish between the 16 black raspberry genotypes. Red raspberry and blackberry could be distinguished from black raspberry by 27 and 29 of 30 RAPD primers tested, respectively. Genetic diversity was most prominent in genotypes from the extremes of the black raspberry indigenous range. Diversifying the germplasm pool for black raspberry cultivar improvement can be achieved through utilizing genotypes from the extremes of the black raspberry range and through interspecific hybridization.
Hannah G. Rempel, Bernadine C. Strik, and Timothy L. Righetti
project. Funding support from the Northwest Center for Small Fruits Research and the Oregon Raspberry and Blackberry Commission is appreciated.