First Report of Vaccinium arboreum Hybrids with Cultivated Highbush Blueberry

Abstract

<jats:p>Over several years, we obtained no hybrids after pollinating thousands of flowers of cultivated tetraploid highbush blueberry (<jats:italic>Vaccinium corymbosum</jats:italic> L. hybrids, section <jats:italic>Cyanococcus</jats:italic>) with pollen from diploid <jats:italic>V. arboreum</jats:italic> Marshall (section <jats:italic>Batodendron</jats:italic>, sparkleberry), a drought-tolerant blueberry relative native in the southeastern United States. In an effort to produce tetraploid <jats:italic>V. arboreum</jats:italic> that could be crossed with highbush blueberry, more than 30,000 seeds were soaked in aqueous colchicine (0.1% to 0.2%) for 24 h or more. The seeds were germinated, and putative tetraploid plants (selected based on morphological characteristics) were grown long enough to obtain pollen for microscopic examination. Twelve selected seedlings that produced unusually large pollen tetrads were used as pollen parents in crosses with more than 40 different tetraploid highbush cultivars and advanced selections. Eighty-six crosses, in which a total of 17,968 flowers were pollinated, gave 1,569 plants that were verified as hybrids after one growing season in the field. Hybrids varied from very weak to quite vigorous, some equaling highbush cultivars in vigor. A few vigorous hybrids were male-sterile, but most had at least some pollen fertility. Of the most vigorous F<jats:sub>1</jats:sub> hybrids, 12 of the most fertile, based on the amount of pollen shed and on the microscopic appearance of the pollen, were backcrossed to highbush cultivars, and 3919 backcross seedlings were obtained. These varied widely in vigor but averaged higher in vigor than their F<jats:sub>1</jats:sub> interspecific hybrid parents.</jats:p>

Construction of a High-Density American Cranberry (Vaccinium macrocarponAit.) Composite Map Using Genotyping-by-Sequencing for Multi-pedigree Linkage Mapping

“…However, due to the high level of synteny and collinearity detected between cranberry and blueberry using cross-transferable SSRs (Schlautman 2016), information from the composite map should also be applicable to many other commercially important Vacciniums including blueberry ( Vaccinium section Cyanococcus ) and closely related sections lingonberry ( Vaccinium section Vitis-Idaea ) and sparkle berry ( Vaccinium section Batodendron ) (Lyrene 2011; Schlautman et al 2016). …”

Construction of a high-density American cranberry (Vaccinium macrocarponAit.) composite map using genotyping-by-sequencing for multi-pedigree linkage mapping

“…The composite map will be most useful for studies within section Oxycoccus, and it may aid in future targeted introgression of genomic regions involved in the expression of unique metabolic pathways or disease resistance genes from the small-fruited cranberry, V. oxycoccos, to the American cranberry, V. macrocarpon (Vorsa and Polashock 2005). However, due to the high level of synteny and collinearity detected between cranberry and blueberry using crosstransferable SSRs (Schlautman 2016), information from the composite map should also be applicable to many other commercially important Vacciniums including blueberry (Vaccinium section Cyanococcus) and closely related sections lingonberry (Vaccinium section Vitis-Idaea) and sparkle berry (Vaccinium section Batodendron) (Lyrene 2011;Schlautman et al 2016).…”

Production of Intersectional Hybrids between Colchicine-induced Tetraploid Shashanbo (Vaccinium bracteatum) and Highbush Blueberry ‘Spartan’

“…breeders for several reasons; for example, it has a wide and deep root system, which makes the plants drought-tolerant, and it can grow well in higher pH soils compared with other species in the section Cyanococcus (Karizumi, 1979;Kunitake et al, 2006;Luby et al, 1991). However, cultivated highbush blueberry requires acidic soil and has shallow, fibrous roots that require continuous moisture in the top 1 m of soil (Lyrene, 2011). Therefore, shashanbo might be used as a good germplasm source to breed highbush blueberry in that they are more adaptable in a broad range of environmental conditions.…”

“…Intersectional crosses have successfully produced several hybrids in Vaccinium (Ballington, 1980(Ballington, , 2001Darrow and Camp, 1945;Lyrene, 2011;Rousi, 1963), but our previous attempts to cross diploid shashanbo with tetraploid highbush blueberry cultivars have not been successful (H. Tsuda, unpublished data). The failure might be attributable in part to the triploid block, which is strong in Vaccinium (Darrow et al, 1944) along with other genetic crossing barriers between the sections Bracteata and Cyanococcus.…”

“…In attempting to cross section Cyanococcus with species of other sections, blueberry breeders typically have used plants with the same chromosome numbers to avoid the ploidylevel barrier in addition to other genetic barriers, which might separate the sections (Lyrene and Ballington, 1986). The hybridization barrier imposed by differences in the ploidy level in blueberry has been overcome by using clones that produce substantial numbers of 2n gametes and colchicine-induced polyploids (Lyrene, 2011). In our previous study, we have succeeded to obtain several tetraploid shashanbo plants by colchicine treatment (H. Tsuda, unpublished data).…”