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  • Author or Editor: Pachanoor S. Devanand x
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Acreages of `Nules' Clementine and `Afourer' mandarin have increased rapidly in California. One way to produce seedless mandarins is using Navel oranges or Satsuma mandarins as buffer to prevent cross-pollination. In order to determine the number of necessary buffer rows or spacing to prevent cross-pollination, we used AFLP markers to determine the pollen parentages of `Nules' and `Afourer' seedlings from two sites. The AFLP markers were able to identify Clementine as pollen parents of 26.6% (25/94) of the `Afourer' seedlings from one site. The pollen of Clementine was able to travel across minimum of 32 rows to pollinate `Afourer' mandarins. We found 12.73% (14/110) of the `Afourer' seedlings at the east side of the site were progenies of `Minneola' tangelo. Pollen of `Minneola' was able to travel across minimum 94 rows to pollinate `Afourer' mandarins. 12.73% (14/110) of the `Afourer' seedlings at the east end of the site were progenies of Clementine. Pollen of Clementine was able to travel minimum 54 rows to pollinate the `Afourer' mandarin at the east end of the site. The AFLP markers also identified `Afourer' mandarin as pollen parents of almost all `Nules' seedlings (98.63%, 72/73) at a second site. The pollen of `Afourer' was able to travel across minimum of 74 acres of empty ground from the east or minimum of 91 rows of Navel (128 acres) from the north to pollinate `Nules' Clementine. The results showed how far can compatible pollens traveled to cause seeds in mandarins in California. The implication from the results in seedless mandarin production in California is discussed.

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Single-nucleotide-polymorphism (SNP) is the most abundant genetic variation among individuals within a species. SNPs can be used as markers for gene discovery and for assessment of biodiversity. We established a practical strategy for discovering candidate SNPs in fruiting-mei (Prunusmume Sieb. et Zucc.), a non-model tree fruit, from amplified-fragment-length-polymorphism (AFLP) fragments. Eighty-one of the 150 chosen bands from 10 cultivars of fruiting-mei were successfully re-amplified and 67 of these re-amplified PCR products yielded 13 groups of reliable sequences. The sequencing results from both directions of 23 randomly selected PCR products using the corresponding selective primers showed that all the purified fragments from the gels were EcoR I-EcoR I fragments. The sequence alignment of 13 groups of sequence yielded 95 SNPs from a total of 5252 bp, averaging one SNP every 55 bp. Among these SNPs, 73 were heterozygous in the loci of some individual cultivars. The SNPs distribution were: 58% transition, 40% transversion, and 2% InDels. There were also one di-nucleotide polymorphism and one tetra-nucleotide deletion. The procedure of SNP isolation from AFLP fragments can be useful for transferring AFLP markers into sequence-tagged-site markers.

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Production of seedless mandarins such as `Nules' clementine mandarin (Citrus clementina Hort. Ex Tan.) and `Afourer' mandarin [C. sinensis (L.) Osbeck × C. reticulata Blanco] is increasing in California as consumers' interest in seedless, easy peeling, and good tasting mandarins increases. The fruit would produce seeds if cross-pollination with compatible pollen source occurred. It is almost impossible to prevent cross-pollination between compatible mandarin cultivars by honeybees (Apis mellifera L.) within the multi-faceted agricultural environment in California. To produce seedless mandarin, growers either plant a single cultivar in a large solid block or try to use pollen-sterile navel oranges (C. sinensis) or satsuma mandarins (C. unshiu Marco.) as buffers to prevent cross-pollination. The question of how many rows of buffer trees or spacing can effectively prevent cross-pollination by honeybees between compatible mandarins is unclear. We initiated a study using fluorescent-labeled AFLP markers to determine the pollen parentages of `Nules' clementine seedlings and `Afourer' mandarin seedlings from two orchards in California. The longest distance of pollen flow at an orchard near Madera was 521 m. The pollen of `Minneola' tangelo (C. reticulata × C. paradisi Macf.) was able to disperse across a minimum of 92 rows of `Lane Late' navel oranges plus two rows of `Afourer' mandarins to pollinate `Afourer' mandarins. We also found that all the seedlings of `Nules' clementine mandarin at an orchard near Bakersfield had been pollinated by `Afourer' mandarin pollen. The pollen of `Afourer' mandarin was able to disperse up to distances between 837 and 960 m to pollinate `Nules' clementine. The pollen dispersal distance found in this study was at least 16 times longer than previously reported in a citrus orchard. Growers need to consider a much larger space or buffer rows to prevent cross-pollination and produce seedless mandarins in California.

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Anthurium is the largest genus in the family Araceae, consisting of about 1000 species. Anthuriums are valued for their colorful spathes and traditionally used as cut flowers. With the introduction of compact cultivars through breeding, a series of container-grown cultivars have been released and widely produced as flowering foliage plants. However, limited information is available about genetic relatedness among these container-grown cultivars. This study analyzed genetic relationships of 58 cultivars using amplified fragment length polymorphism (AFLP) markers with near infrared fluorescence labeled primers. Forty-eight EcoR I + 2/Mse I + 3 primer set combinations were screened from which six primer sets were selected and used in this investigation. Each selected primer set generated 94 to 115 scorable fragments. A total of 647 AFLP fragments were detected of which 401 were polymorphic (67%). All cultivars were clearly differentiated by their AFLP finger-prints. A dendrogram was constructed using the unweighted pair-group method of arithmetic averages (UPGMA) technique and a principal coordinated analysis (PCA) was used to analyze the relationships. The 58 cultivars were divided into three clusters; clusters I, II, and III had 40, 10, and 8 cultivars, respectively. Most commonly grown cultivars were positioned in cluster I, where had Jaccard similarity coefficients among them ranged from 0.7 to 0.98. Eighteen of the 40 shared Jaccard similarity coefficient of 0.8 or higher, indicating that genetic diversity for cultivated container-grown Anthurium is needed.

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Peace lily (Spathiphyllum Schott) is one of the most popular tropical ornamental foliage plants and is used worldwide for interiorscaping. However, little information is available on the genetic relationships of cultivars. Using amplified fragment length polymorphism (AFLP) markers with near-infrared fluorescence-labeled primers, this study analyzed genetic relatedness of 63 commercial cultivars and breeding lines. Forty-eight EcoRI + 2/MseI + 3 primer set combinations were initially screened, from which six primer sets were selected and used in this investigation. All cultivars were clearly differentiated by their AFLP fingerprints, and the relationships were analyzed using the unweighted pair-group method of arithmetic average cluster analysis (UPGMA). The 63 cultivars were divided into four clusters. All commercial cultivars or breeding lines resulted from crosses of some of the cultivars, a total of 45, were positioned in cluster I with Jaccard's similarity coefficients between 0.61 and 0.88. There was only one cultivar in cluster II. Cluster III contained 16 cultivars; they are either species or breeding lines generated from interspecific hybridization. Cluster IV had one unknown species. This study provides genetic evidence as to why cultivars from cluster I and III are not readily crossable because the Jaccard's similarity coefficient between the two clusters was only 0.35. Results also indicate that commercial cultivars are genetically close. Strategies for increasing genetic diversity of cultivated peace lily should be sought for future breeding efforts.

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Philodendrons (Philodendron Schott) are among the most popular tropical ornamental foliage plants used for interior decoration. However, limited information is available on the genetic relationships among popular Philodendron species and cultivars. This study analyzed genetic similarity of 43 cultivars across 15 species using amplified fragment length polymorphism (AFLP) markers with near infrared fluorescence labeled primers. Forty-eight EcoR I + 2/Mse I + 3 primer set combinations were screened, from which six primer sets were selected and used in this investigation. Each selected primer set generated 96 to 130 scorable fragments. A total of 664 AFLP fragments were detected, of which 424 (64%) were polymorphic. All cultivars were clearly differentiated by their AFLP fingerprints, and the relationships were analyzed using the unweighted pair-group method of arithmetic average cluster analysis (UPGMA) and principal coordinated analysis (PCA). The 43 cultivars were divided into five clusters. Cluster I comprises eight cultivars with arborescent growth style. Cluster II has only one cultivar, `Goeldii'. There are 16 cultivars in cluster III, and most of them are self-heading interspecific hybrids originated from R.H. McColley's breeding program in Apopka, Fla. Cluster IV contains 13 cultivars that exhibit semi-vining growth style. Cluster V has five cultivars that are true vining in morphology, and they have lowest genetic similarity with philodendrons in other clusters. Cultivated philodendrons are generally genetically diverse except the self-heading hybrids in cluster III that were mainly developed using self-heading and semi-vining species as parents. Seven hybrid cultivars have Jaccard's similarity coefficients of 0.88 or higher, suggesting that future hybrid development needs to select parents with diverse genetic backgrounds.

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Dieffenbachia Schott is an important ornamental foliage plant genus. A total of 30 species has been recognized, but most cultivars come from or are related to a single species, D. maculata (Lodd.) G. Don. At least 11 of the cultivars are sports or somaclonal variants. As a result, the potential lack of genetic diversity in cultivated Dieffenbachia has become a concern. However, no research has been conducted to determine the genetic relatedness of the cultivars. This study analyzed the genetic similarity of 42 Dieffenbachia cultivars using amplified fragment length polymorphism (AFLP) markers. Six primer sets, selected from an initial screening of 48, generated a total of 453 scorable AFLP fragments of which 323 (71%) are polymorphic. All cultivars were clearly differentiated by their AFLP fingerprints. A dendrogram was constructed using the unweighted pair-group method of arithmetic averages, and principal coordinated analysis was carried out to show multiple dimensions of the distribution of the cultivars. The 42 cultivars were divided into three clusters; clusters I and II comprise 18 and 23 cultivars, respectively. Jaccard's similarity coefficients for cultivars in the clusters I and II varied from 0.44 to 0.95 and 0.41 to 0.87, respectively. These results indicate that broadening the genetic variability in the Dieffenbachia gene pool is needed, but the genetic similarity of many cultivars is not as close as previously thought. Additionally, Jaccard's similarity coefficients between most sports or somaclonal variants and their parents were 0.73 or lower, suggesting that accumulation of somatic mutations through tissue culture may play a role in the increased variation between some sports or variants and their parents.

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