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- Author or Editor: Denita Hadziabdic x
Axillary and apical buds from five Cornus kousa cultivars (`Little Beauty', `Samaritan', `Heart Throb', `Rosabella', and `Christian Prince') were initially established on two basal media, woody plant medium (WPM) and woody plant medium/broad leaved tree medium (BW), amended with the following concentrations of 6–benzylaminopurine (BA): 0, 2, 4, and 8 μm. After explants were transferred at 4-week intervals for 28 weeks beginning in April, only microshoots of `Samaritan', `HeartThrob' and `Rosabella', were harvested from proliferating cultures and placed on rooting media. `Little Beauty' and `Christian Prince' did not perform well in multiplication phase of tissue culture and were excluded from further studies. Rooting media contained WPM or BW supplemented with either 1-naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA) or indole-3-acetic acid (IAA) at the following concentrations: 0, 0.5, 1.5, 4.5, and 13.5 μm. Six weeks following rooting experiment, preliminary data were collected and results showed that total of nine plants rooted on both WPM and BW media supplemented with IBA, 17 plants rooted on media supplemented with NAA, and 14 plants rooted on media supplemented with IAA. These results indicated that NAA and IAA appeared to be better for root production on C. kousa cultivar microshoots than IBA. Additionally, WPM supported more root production, when compared to BW, even though both media resulted in rooted microshoots. Proliferating masses were placed on fresh medium with 2μm BA and were used again for the rooting projects.
Axillary buds from a single Cladrastis kentukea tree were initially cultured on two media, woody plant medium (WPM) and Murashige and Skoog (MS) containing 0, 1, 2, or 4 μm 6–benzylaminopurine (BA). Cultures were transferred to fresh media every 4 weeks. Elongated shoots were harvested after 39 weeks and transferred to half-strength MS medium supplemented with the following concentrations of IBA: 0, 3, 30, 100, and 300 μm for 3 d, then returned to half-strength MS without growth regulators. Explants exposed to 300 μm of IBA produced significantly more roots (75%) compared to explants exposed to other treatments. Fifty-four and 45% of the microshoots rooted when exposed to 100 and 30 μm IBA, respectively. Only 4% of the microshoots rooted when exposed to 3 μm IBA and none of the control microshoots rooted. Although the 300 μm treatment yielded the most rooted plantlets, there was significantly higher terminal meristem abortion compared to other treatments. There were no statistical differences between the numbers of roots and total root length among all treatments. Additionally, all microshoots that rooted had lenticels, suggesting that presence of lenticel cambial activity can possibly improve rooting abilities of selected microshoots. Rooted microshoots were gradually acclimatized to nonsterile environment.
Lagerstroemia L. (crape myrtle) is an economically important woody plant genus with several deciduous flowering ornamental species. A wide range of flower colors, long flowering periods, growth habits ranging from miniature to tree sizes, and exfoliating bark characteristics provide horticulturists and nursery growers with a great deal of interest in the breeding and genetics of this genus. We report microsatellite marker development from a GT-enriched genomic library of the interspecific hybrid ‘Natchez’ (L. indica L. × L. fauriei Koehne). Twelve of 43 novel microsatellite loci were characterized on a collection of 33 Lagerstroemia cultivars and accessions. Four to eight alleles per locus (mean = 5.6 alleles) were detected. Allelic richness ranged from 3.9 to 7.2 with a mean of 5.3. The level of polymorphism detected (average gene diversity of 0.68) indicates moderately high genetic diversity within the selections of crape myrtle cultivars and accessions. The examined markers also exhibited high cross-species transferability to L. fauriei, L. limii Merr., and L. subcostata Koehne.
Viburnum rufidulum is a deciduous tree native to North America that has four-season appeal, which provides commercial horticultural value. In addition, the plant has unique and attractive red pubescence on leaf buds and petioles, common to no other Viburnum species. As habitat undergoes development and subsequent fragmentation of native plant populations, it is important to have baseline genetic information for this species. Little is known about the genetic diversity within populations of V. rufidulum. In this study, seven microsatellite loci were used to measure genetic diversity, population structure, and gene flow of 235 V. rufidulum trees collected from 17 locations in Kentucky and Tennessee. The genotype data were used to infer population genetic structure using the program InStruct and to construct an unweighted pair group method with arithmetic mean dendrogram. A single population was indicated by the program InStruct and the dendrogram clustered the locations into two groups; however, little bootstrap support was evident. Observed and expected heterozygosity were 0.49 and 0.78, respectively. Low-to-moderate genetic differentiation (F ST = 0.06) with evidence of gene flow (Nm = 4.82) was observed among 17 populations of V. rufidulum. A significant level of genetic diversity was evident among V. rufidulum populations with most of the genetic variations among individual trees (86.37%) rather than among populations (13.63%), and a Mantel test revealed significant correlation between genetic and geographical distance (r = 0.091, P = 0.001). The microsatellites developed herein provide an initial assessment or a baseline of genetic diversity for V. rufidulum in a limited area of the southeastern region of the United States. The markers are a genetic resource and can be of assistance in breeding programs, germplasm assessment, and future studies of V. rufidulum populations, as this is the first study to provide genetic diversity data for this native species.