Chad E. Finn

Antioxidant properties of domesticated and wild Rubus species.

The antioxidative capacities of a number of Rubus species of varied pigmentation have been investigated. In addition, total phenol, anthocyanin and ascorbic acid contents have been determined. Two methods to assess the antioxidant potential of fruit juices have been used. The antioxidant capacities of the fruit ranged from 0 to 25.3 mmol Trolox equivalents g ˇ1 (TEAC) or from 190 to 66000 mmol l ˇ1 ferric reducing antioxidant power (FRAP). Ascorbic acid contributes only minimally to the antioxidant potential of Rubus juices (<10%, TEAC). There are apparent linear relationships between antioxidant capacity (assessed as both TEAC and FRAP) and total phenols (r xy = 0.6713 and 0.9646 respectively). Also, anthocyanin content has a minor influence on antioxidant capacity (r xy = 0.3774, TEAC; r xy =0.5883, FRAP). The sample with the highest antioxidant capacity (Rubus caucasicus) had the highest phenol content, but only a low percentage was represented by antho- cyanins. The present study demonstrates the potential of certain wild Rubus species, notably R caucasicus, for improvement of nutritional value through germplasm enhancement programmes. # 2000 Society of Chemical Industry

Blueberries and Cranberries

Most blueberry breeding activity is focused on northern highbush, southern highbush and rabbiteye types. The major objectives of blueberry breeders center on high plant vigor, improved disease resistance, flavor, longer storing fruit and expanded harvest dates. Cranberry breeders have concentrated on early maturing fruit, uniform large size, intense color, keeping quality, high productivity, disease resistance and plant vigor. Considerable variability exists in blueberry and cranberry for most of the horticulturally important traits, and while only a limited number of genetic studies have been performed, most inheritance patterns fit quantitative models. Several genes have been identified through molecular, genetic and genomic approaches that are associated with cold hardiness. Wide hybridization is commonly employed in blueberry breeding and southern highbush types were derived primarily by incorporating genes from the diploid species Vaccinium darrowii into the highbush background via unreduced gametes. A wide array of molecular markers has been used in blueberry for fingerprinting and linkage mapping, and a major QTL regulating the chilling requirement in diploids has been identified. Transgenic blueberries have been produced with herbicide resistance and the Bt gene (Bacillus thuringiensis) has been incorporated into cranberry. A large EST library of highbush blueberry has been produced.

Genetic diversity in wild and cultivated black raspberry (Rubus occidentalis L.) evaluated by simple sequence repeat markers

Breeding progress in black raspberry (Rubus occidentalis L.) has been limited by a lack of genetic diversity in elite germplasm. Black raspberry cultivars have been noted for showing very few phenotypic differences and seedlings from crosses between cultivars for a lack of segregation for important traits. Despite these challenges, little molecular work has been done to explore genetic diversity and relationships in wild and cultivated black raspberry germplasm. Microsatellite, or simple sequence repeat (SSR), markers are highly polymorphic codominant markers useful for studying genetic diversity, population genetics, genetic fingerprinting and other applications. We examined genetic diversity in 148 wild and cultivated black raspberry accessions using 21 polymorphic SSR markers. Black raspberry cultivars clustered tightly and showed higher than expected heterozygosity while that of wild accessions was low. Relationships between wild black raspberry accessions were poorly resolved and regional clusters were mostly absent from our analysis. Our results indicated that wild black raspberry germplasm is a relatively untapped resource available for future breeding.

A genetic linkage map of black raspberry (Rubus occidentalis) and the mapping of Ag 4 conferring resistance to the aphid Amphorophora agathonica

Key messageWe have constructed a densely populated, saturated genetic linkage map of black raspberry and successfully placed a locus for aphid resistance.AbstractBlack raspberry (Rubus occidentalis L.) is a high-value crop in the Pacific Northwest of North America with an international marketplace. Few genetic resources are readily available and little improvement has been achieved through breeding efforts to address production challenges involved in growing this crop. Contributing to its lack of improvement is low genetic diversity in elite cultivars and an untapped reservoir of genetic diversity from wild germplasm. In the Pacific Northwest, where most production is centered, the current standard commercial cultivar is highly susceptible to the aphid Amphorophora agathonica Hottes, which is a vector for the Raspberry mosaic virus complex. Infection with the virus complex leads to a rapid decline in plant health resulting in field replacement after only 3–4 growing seasons. Sources of aphid resistance have been identified in wild germplasm and are used to develop mapping populations to study the inheritance of these valuable traits. We have constructed a genetic linkage map using single-nucleotide polymorphism and transferable (primarily simple sequence repeat) markers for F1 population ORUS 4305 consisting of 115 progeny that segregate for aphid resistance. Our linkage map of seven linkage groups representing the seven haploid chromosomes of black raspberry consists of 274 markers on the maternal map and 292 markers on the paternal map including a morphological locus for aphid resistance. This is the first linkage map of black raspberry and will aid in developing markers for marker-assisted breeding, comparative mapping with other Rubus species, and enhancing the black raspberry genome assembly.

Generating Genomic Tools for Blueberry Improvement

Because of their recognized health benefits, there has been increased demand and consumption of blueberries in recent years. Great strides have been made in blueberry cultivar development since its domestication using traditional breeding approaches. However, genomic tools that could be used to hasten improvement are lacking. The aim of our Specialty Crop Research Initiative project, funded at the end of 2008, is to develop genomic tools for molecular breeding and assessing genetic diversity of blueberry. Marker-assisted breeding would be particularly useful for combining traits for climatic adaptation with those for improved fruit and nutritional quality in highbush blueberry (Vaccinium corymbosum). Genomic resources being developed include expressed sequence tag libraries, expressed sequence tag-based molecular markers, and genetic linkage maps. Transcriptome sequences have been generated from fruit at different stages of development, flower buds at different stages of cold acclimation, and leaves by 454 sequencing. About 600,000 sequences have been assembled into approximately 15,000 contigs. Markers derived from expressed sequence tags (simple sequence repeats and expressed sequence tag-polymerase chain reaction markers) are being used to identify quantitative trait loci associated with cold hardiness, chilling requirement, and fruit quality traits, in studies of genetic diversity, spatial genetic structure, and gene flow in the wild lowbush blueberry (V. angustifolium), and to construct a phylogenetic tree of Vaccinium species in the section Cyanococcus. Availability of these genomic tools will allow future advances, such as the development of a blueberry microarray to facilitate studying gene expression and the use of marker-assisted breeding.

Blackberry cult ivation in the world

Blackberries have now become a common fruit in marketing outlets, particularly in North America and the European Union. Blackberries have enjoyed expansion due to a combination of factors including improved cultivars, expanded marketing efforts and fruit availability, and an overall increase in berry consumption, especially as fresh fruit, in many areas of the world. It is estimated that cultivated blackberries are grown in excess of 25,000 ha worldwide. World production, and cultivation are commented.The rapid expansion of the blackberry industry has been remarkable. New, higher quality, cultivars, modified production practices and new production regions have all combined to make this crop one that consumers expect to be available fresh year-round in their grocery stores. As new cultivars are developed that combine the industrys need for high quality arrivals with increased flavors and expanded dates of harvest, the blackberry industry should expand further.

First Report of Raspberry bushy dwarf virus in Rubus multibracteatus from China

Raspberry bushy dwarf virus (RBDV), genus Idaeovirus, has been reported in commercial Rubus spp. from North and South America, Europe, Australia, New Zealand, and South Africa. Infection can cause reduced vigor and drupelet abortion leading to crumbly fruit and reduced yields (3,4). In recent years, Rubus germplasm in the form of seed, was obtained on several collection trips to The Peoples Republic of China to increase the diversity of Rubus spp. in the USDA-ARS National Clonal Germplasm Repository, (Corvallis, OR). Before planting in the field, seedlings were tested for the presence of RBDV, Tomato ringspot virus, and Tobacco streak virus using triple-antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) (antiserum produced by R. R. Martin). One symptomless plant of R. multibracteatus H. Lev. & Vaniot (PI 618457 in USDA-ARS GRIN database), from Guizhou province in China, tested positive for RBDV (RBDV-China). After mechanical transmission on Chenopodium quinoa Willd., this isolate produced typical symptoms of RBDV (3). To determine if RBDV-China was a contaminant during the handling of the plants, or if the source was a seedborne virus, the coat protein gene was sequenced and compared to published sequences of RBDV. RNA was extracted from leaves of R. multibracteatus and subjected to reverse transcription-polymerase chain reaction (RT-PCR) using primers that flank the coat protein gene. Products from four separate PCR reactions were sequenced directly or were cloned into the plasmid vector pCR 2.1 (Invitrogen, Carlsbad, CA) and then sequenced. The coding sequence of the coat protein gene of RBDV-China was 87.5% (722/825) identical to that isolated from black raspberry (Genbank Accession No. s55890). The predicted amino acid sequences were 91.6% (251/274) identical. Previously, a maximum of five amino acid differences had been observed in the coat proteins of different RBDV strains (1). The 23 differences observed between RBDV-China and the isolate from black raspberry (s55890) confirm that the RBDV in R. multibracteatus is not a greenhouse contaminant but is indeed a unique strain of RBDV. In addition, monoclonal antibodies (MAbs) to RBDV (2) were tested against RBDV-China. In these tests, MAb D1 did not detect RBDV-China, whereas MAb R2 and R5 were able to detect the strain. This is the first strain of RBDV that has been clearly differentiated by MAbs using standard TAS-ELISA tests. Although RBDV is common in commercial Rubus spp. worldwide, to our knowledge, this is the first report of RBDV in R. multibracteatus, and the first report of RBDV from China. The effects of this new strain of RBDV could be more or less severe, or have a different host range than previously studied strains. It is more divergent from the type isolate than any other strain that has been studied to date. Phylogenetic analysis of coat protein genes of RBDV may be useful in understanding the evolution and spread of this virus. References: (1) A. T. Jones et al. Eur. J. Plant Pathol. 106:623, 2000. (2) R. R. Martin. Can. J. Plant. Pathol. 6:264, 1984. (3) A. F. Murant. Raspberry Bushy Dwarf. Page 229 in: Virus Diseases of Small Fruits. R. H. Converse, ed. U.S. Dep. Agric. Agric. Handb. 631, 1987. (4) B. Strik and R. R. Martin. Plant Dis. 87:294, 2003.

Mistaken identity: clarification of Rubus coreanus Miquel (Bokbunja).

In the U.S., there has been a recent surge in Korean black raspberry products available and in the number of reports about this species appearing in the scientific literature. Despite this, the majority of products sold and the work carried out has been on Rubus occidentalis L., not R. coreanus Miquel. The importance of accurate recognition of all starting material is multiplied for research downstream, including genetics/genomics, plant breeding, phenolic identification, food processing improvements and pharmacokinetic investigations. An overview of distinguishing characteristics separating R. coreanus from R. occidentalis will be presented. Research conducted on correctly identified fruit will also be summarized to aid future studies that might showcase the unique qualities that bokbunja can offer.

Validation of molecular markers associated with perpetual flowering in Octoploid Fragaria germplasm

Perpetual-flowering (PF) is a highly desirable trait within cultivated strawberries (Fragaria ×ananassa) for the commercial and home garden markets. The most widely used source of the PF trait was originally introgressed from a wild F. virginiana subsp. glauca accession collected in the Wasatch Mountains near Salt Lake City, UT in 1955. This source is conferred by a single dominant QTL, FaPFRU, and was recently identified in multiple bi-parental populations. Multiple markers have been proposed as diagnostic tests for marker-assisted selection (MAS). These markers were proposed after looking at a relatively small sample of germplasm. To identify the best diagnostic testing procedure for MAS, the markers were evaluated individually and in combination on a training set of cultivars with known genotypes and the best test was used to determine the distribution of the FaPFRU source of PF within a large sample of octoploid Fragaria germplasm. Of the tests evaluated, the microsatellite marker Bx215 alone was found to have the best diagnostic ability for MAS with an accuracy of 93.1% in controlled conditions. When utilizing the test on 390 F. ×ananassa accessions, 164 accessions were identified to likely have the FaPFRU locus. Nine octoploid Fragaria accessions were PF and did not have this marker, indicating possible recombination events or potentially novel sources of the PF trait. Future work will be needed to dissect the PF trait in these nine individuals.

Identification of QTL associated with flower and runner production in octoploid strawberry (Fragaria×ananassa)

BACKGROUND: Understanding the genetics of flowering in the strawberry (Fragaria × ananassa) will aid in the development of breeding strategies. OBJECTIVE: To search for quantitative trait loci (QTL) associated with remontancy and weeks of flowering in the strawberry. METHODS: Previously collected phenotypic data from two non-remontant ‘Honeoye’ × remontant ‘Tribute’ strawberry populations and simple sequence repeats (SSR) markers were used to search for QTL associated with repeat flowering, weeks of flowering and runner production, as well as the ability to produce flowers and runners at 17, 20 and 23 ◦ C. RESULTS: As was discovered in other studies, we found a major QTL that regulated remontancy and weeks of flowering on homeologous linkage group IV of ‘Tribute’. This QTL also had a negative effect on runner production and a positive influence on flower production under high temperatures. A number of additional QTL were discovered that significantly (LOD >3.0) influenced flower and runner production. CONCLUSIONS: Remontancy/non-remontancy is controlled by a major gene/locus and several minor modifying ones.