Domestication of clonally propagated crops such as pineapple from South America was hypothesized to be a ‘one-step operation’. We sequenced the genome of Ananas comosus var. bracteatus CB5 and assembled 513 Mb into 25 chromosomes with 29,412 genes. Comparison of the genomes of CB5, F153 and MD2 elucidated the genomic basis of fiber production, color formation, sugar accumulation and fruit maturation. We also resequenced 89 Ananas genomes. Cultivars ‘Smooth Cayenne’ and ‘Queen’ exhibited ancient and recent admixture, while ‘Singapore Spanish’ supported a one-step operation of domestication. We identified 25 selective sweeps, including a strong sweep containing a pair of tandemly duplicated bromelain inhibitors. Four candidate genes for self-incompatibility were linked in F153, but were not functional in self-compatible CB5. Our findings support the coexistence of sexual recombination and a one-step operation in the domestication of clonally propagated crops. This work guides the exploration of sexual and asexual domestication trajectories in other clonally propagated crops.

Domestication of clonally propagated crops was hypothesized as a single step (one generation) operation. Pineapple is a clonally propagated crop domesticated in South America. The role and extent of sexual reproduction in pineapple domestication are unknown. We re-sequenced 78 cultivated and 11 wild accessions to investigate its domestication history. Ananas comosus cultivars exhibit a complex history of ancient and recent admixture. The widespread lack of mitotic selection signals suggests that pineapple domestication have been mainly through sexual reproduction. We identified 25 selective sweeps in pineapple, including a strong sweep containing two tandemly duplicated bromelain inhibitors that delays fruit senescence. Two tightly linked candidate genes were identified for gametophytic self-incompatibility. Our findings challenge conventional view of domestication in clonally propagated crops, and few, if any, fit the definition of one-step operation. This investigation offers novel approaches to explore sexual and asexual processes in shaping domestication trajectories in other clonally propagated crops.

‘Norman’ is the third cultivar released from the University of Arkansas blueberry breeding program, which began in the late 1970s and has involved cooperative efforts with the U.S. Department of Agriculture (USDA). Previous cultivars released from this breeding program were ‘Ozarkblue’ (Clark et al., 1996) and ‘Summit’ (Clark and Moore, 1999). ‘Norman’ is named in honor of Dr. James Norman Moore, who began the Arkansas fruit breeding program in 1964 and led the program for 33 years. ‘Norman’ is a southern highbush (Vaccinium spp.) cultivar with yield comparable to ‘Bluecrop’, ‘Ozarkblue’, and ‘Summit’. Fruit size is comparable to ‘Ozarkblue’ and larger than ‘Bluecrop’ and its firmness is superior to ‘Bluecrop’, ‘Ozarkblue’, and ‘Summit’. ‘Norman’ ripens 5 d after ‘Bluecrop’ and 8 d before ‘Ozarkblue’. Plants of ‘Norman’ have an estimated chilling requirement of 600 h (hours below 7 C), which is lower than that for ‘Bluecrop’ and ‘Ozarkblue’.

One hundred S. l. var. cerasiforme (Dunal) accessions from the ‘Tanksley’ designated core collection were evaluated for horticultural quality under greenhouse conditions. Fourteen selected accessions were grown under field conditions in a replicated trial to evaluate the fruit for phenolic content. Total fruit phenolics ranged from 44 to 82 mg/100 g gallic acid equivalents (GAE) fresh weight (FW) as measured by Folin-Ciocalteau assay (F-C), and 12 to 108 mg/100 g FW as measured by high-performance liquid chromatography (HPLC). Five accessions (LA1712, LA1455, LA2633, LA1668, and LA2632) had significantly higher total phenolics (F-C) than cultivars ( P ≤ 0.05). These five accessions also possessed interesting phenolics profiles, including high levels of caffeoylquinic acids (LA1620, LA1455, and LA2633) and rutin (LA2633).

Cultivated tomatoes (Solanum lycopersicum L.) produce anthocyanins in vegetative tissues and certain flavonols can be found in the fruit. Some related wild species do produce anthocyanins in the fruit, and this trait has been transferred into cultivated tomato. Fruit with the genes Abg, Aft, and atv exhibit varying degrees of anthocyanin production in the epidermis, but not in the fruit pericarp. Fruit with these alleles in various combinations were analyzed to characterize the anthocyanidin profile, moieties, and total anthocyanin content. In general, combining atv with either Aft or Abg substantially increased anthocyanin production in the fruit. Over 23 different anthocyanins were detected, petunidin-3-(p-coumaryl)-rutinoside-5-glucoside being predominant. The highest level of anthocyanin expression was observed in small fruit with the genotype Abg- atvatv and AftAft atvatv, well in excess of 100 mg/100 g fresh weight of epidermis and subepidermis depending on the size of the fruit. Nonanthocyanin flavonoids were also upregulated in proportion to the anthocyanin concentration. The anthocyanin genes were also combined with genes affecting carotenoid composition and content. Reduced carotenoid content conditioned by the alleles B (Beta) and r (yellow flesh) was associated with lower total anthocyanins, an unexpected observation because the carotenoid and anthocyanin pathways are thought to be independent. The level of anthocyanin did not affect carotenoid profiles or amounts.

Published March 2007. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog

Sixty-nine accessions representing wild and domesticated highbush blueberry (Vaccinium corymbosum L.) germplasm were genotyped using 28 simple sequence repeats (SSRs). A total of 627 alleles was detected and unique fingerprints were generated for all accessions. Suspected duplicate accessions of 'Coville' and 'Ivanhoe' had DNA fingerprints that were identical to 'Coville' and 'Ivanhoe', respectively. Genetic similarity measures placed wild and cultivated blueberries in separate groups. Northern highbush blueberries grouped among ancestral clones that were used extensively in blueberry breeding such as 'Rubel' and 'Stanley'. Southern highbush blueberries formed a separate group from northern highbush blueberries. The microsatellite markers used here show excellent promise for further use in germplasm identification, in genetic studies of wild Vaccinium L. populations, and for constructing linkage maps.

Primers were designed to amplify 36 simple sequence repeat (SSR) sequences identified in an Expressed Sequence Tag (EST) library derived from Vaccinium corymbosum. They were tested for amplification in other species of the genus Vaccinium. Two representatives each from the species V. ovatum, V. arboreum, V. elliottii, V. tenellum, V. darrowii, V. bracteatum, V. oldhaniii (one representative only), V. macrocarpon, V. vitis-idea, V. parvifolium, V. crassifolium and diploid V. corymbosum were tested. Sixteen SSRs were amplified in all genotypes tested. Analysis of variance indicated significant differences between species in the number of loci that were amplified. EST-SSR loci developed in tetraploid V corymbosum were most easily transferable to other members of section () Cyanococcus and least easily transferable to sections Oxycoccos, Herpothamnus, Myrtillus, and Batodendron in descending order. Several loci amplified exclusively in sections Cyanoccus, Batodendron, Bracteatum and Ciliata, possibly indicating a genetic link between Vaccinium in the southeastern United States and those present in Asia.

We present 30 microsatellite loci isolated from expressed sequence tag (EST) and genomic libraries in Vaccinium corymbosum L. Allele number per locus in 11 tetraploid and one diploid V. corymbosum accessions ranged from two to 15 (mean = 8.16) in 24 single-locus simple sequence repeats (SSRs). Cross-species amplification in a panel of 12 species representing nine sections ranged from 30 to 100% (mean = 83%).

Microsatellite markers for blueberry ( Vaccinium L.) were created from a preexisting blueberry expressed sequence tag (EST) library of 1305 sequences and a microsatellite-enriched genomic library of 136 clones. Microsatellite primers for 65 EST-containing simple sequence repeats (SSRs) and 29 genomic SSR were initially tested for amplification and polymorphism on agarose gels. Potential usefulness of these SSRs for estimating species relationships in the genus was assessed through cross-species transference of 45 SSR loci and cluster analysis using genetic distance values from five highly polymorphic EST-SSR loci. Cross-species amplification for 45 SSR loci ranged from 17% to 100%, and was 83% on average in nine sections. Cluster analysis of 59 Vaccinium species based on genetic distance measures obtained from 5 EST-SSR loci supported the concept of V. elliotii Chapm. as a genetically distinct diploid highbush species and indicated that V. ashei Reade is of hybrid origin. Twenty EST-SSR and 10 genomic microsatellite loci were used to determine genetic diversity in 72 tetraploid V. corymbosum L. accessions consisting mostly of common cultivars. Unique fingerprints were obtained for all accessions analyzed. Genetic relationships, based on microsatellites, corresponded well with known pedigree information. Most modern cultivars clustered closely together, but southern highbush and northern highbush cultivars were sufficiently differentiated to form distinct clusters. Future use of microsatellites in Vaccinium will help resolve species relationships in the genus, estimate genetic diversity in the National Clonal Germplasm Repository (NCGR) collection, and confirm the identity of clonal germplasm accessions.

Published March 2006. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog