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Qingling Li, Yuesheng Yang and Hong Wu

, 1968 ; Wan et al., 1989 ). This kind of chimera has frequently been observed in the process of chromosome doubling ( Chen and Gao, 2007 ; Ning et al., 2009 ; Petersen et al., 2003 ; Roy et al., 2001 ; Thao et al., 2003 ). In plant science, the term

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Min Zhang, Xiuxin Deng, Changping Qin, Chunli Chen, Hongyan Zhang, Qing Liu, Zhiyong Hu, Linlin Guo, Wenhua Song, Yong Tan and Shengcai Liao

-corpus” theory, a plant chimera is a mosaic in which genetically different cells exist in the shoot apical meristem that gives rise to cells that develop into organs of the plant. Graft chimeras arisen spontaneously or by artificial synthesis have been reported

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Karen R. Harris-Shultz, Brian M. Schwartz and Jeff A. Brady

( Hocquigny et al., 2004 ). These plants are periclinal chimeras because one or two entire cell layers of the apical meristem are genetically distinct from the adjacent layers. Periclinal chimeras are often stable and can be maintained by vegetative

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Kuniaki Sugawara, Atsushi Oowada, Takaya Moriguchi and Mitsuo Omura

Random amplified polymorphic DNA (RAPD) markers were used to detect chimerism of citrus cultivars. Polymerase chain reaction conditions suitable for discriminating citrus chimeras were determined. Primers that produced consistent and repeatable bands that differed between the parental cultivars were chosen to create discriminating band patterns. Our results show that selected 12-mer primers can be useful for identifying the four citrus chimeras tested using RAPD technology.

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Grace Q. Chen

inherited genes into the next generation of seeds. High frequencies of chimeras were reported in these studies ( Skarjinskaia et al., 2003 ; Wang et al., 2008 ). Because chimeras give rise to non-transgenic gametes and progenies, it is an obstacle to

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Huey-Jen Chen and Harry Jan Swartz

Several authors report the synthesis of periclinal chimeras generated from graft unions of Solanaceous plants grown in the greenhouse. As this technique requires shoot organogenesis, in vitro conditions are necessary to adapt this technique to woody species. We now report several in vitro techniques necessary to mimic the in vivo graft chimera process. These include rootstock/scion preparation, micrografting and shoot organogenesis from graft unions. Zeatin and auxins have been helpful in preparing graftable material and for increasing the percentage successful grafts. A shorter exposure to organogenic medium containing thidiazuron resulted in greater percentage shoot regeneration from graft unions. Thorny/thornless Rubus and 'Liberty'/'Golden Delicious' or 'Gala' Malus (color) markers are being used to determine the percentage of these regenerants which are chimeral.

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Meryem Ipek, Ahmet Ipek, Douglas Senalik and Philipp W. Simon

mitochondrial–plastid chimera detected in bolting garlic types and investigate the possible use of this chimera as a polymerase chain reaction (PCR)-based marker to discriminate bolting garlic clones from nonbolting or incomplete-bolting garlic clones

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R. Crofton Sloan Jr.

The sweetpotato foundation seed program in Mississippi is committed to producing and supplying high-quality sweetpotato seed to the Mississippi sweetpotato industry. In 1991, a study was initiated to evaluate the effects of small heteroclinal chimeras in foundation seed roots on the root flesh quality in subsequent generations. The presence of small heteroclinal chimeras in parent seed roots did not increase the number or size of chimeras in three subsequent generations of storage roots.

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Katherine Kelly Stephenson, John R. Stommel and Timothy J Ng

A protocol was developed to make in vitro graft unions among Lycopercicon spp., and regenerates from cultured graft unions were evaluated for chimera formation. Young seedlings were preconditioned for 4 to 6 days in liquid 1/2-strength Murashige & Skoog (MS) basal medium supplemented with 8.9 μM benzyladenine and 1.0 μM indole-3-butyric acid. Preconditioned seedlings exhibited increased biomass and enhanced graft union survival. In particular, survival of cleft grafts increased from 37% to 95% with the seedling preconditioning. When graft unions among different genotypes were excised from apex-to-apex in vitro cleft grafts and plated on MS basal medium supplemented with 9.1 μM zeatin and 3.9 μM ancymidol, as many as 100 plantlets were regenerated from a single graft union. However, no chimeric regenerates were recovered, indicating that asymmetric responses to grafting may be a limiting factor to in vitro chimera formation.

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Thomas M. Gradziel and Mary Ann Thorpe

Somatic mutations in shoot growing points, while considered relatively common in many horticultural clones, cannot be detected unless the mutation results in a distinguishable change and comes to occupy sufficient shoot area to be observable. Noninfectious bud-failure (BF) in almond, a genetic mutation which results in failure during early development of vegetative but not flower buds, behaves as a chimera in its incidence within an affected tree and in vegetative progeny from bud-failure prone clonal sources (i.e., vegetative lineage). Early stages of BF development are thought to occur as very limited and so undetected sectorial or mericlinal chimeras. Detection of BF during these early stages would be very valuable for the selection of low-BF source clones for nursery increase. Flower symmetry, as measured by differences in the size of each of the five petals of an almond flower, was evaluated as an indicator of the relative fitness of the individual cell lineages from which different petals were derived. Several hundred flowers from individual clonal sources of the almond variety `Nonpareil', known to produce either very low, medium, or very high levels of BF in their vegetative progeny, were tested over 3 separate years. Significant reductions in flower symmetry were consistently observed for medium BF potential clonal sources relative to either low- or high-BF sources despite the lack of any observable BF symptoms in the medium-BF trees tested. Associated with asymmetric-flower-prone sources was a greater number of an easily distinguishable distorted petal morphology. Medium BF-potential sources consistently produced 2- to 3-fold greater numbers of this petal morphology relative to low BF-sources, although the occurrence of distorted petals in both low and medium BF sources limits its use as an efficient field selection tool. Research findings, however, are allowing a more detailed understanding of the developmental ontogeny of “bud-sport” mutations and may have application in the analysis of otherwise hidden chimeras resulting from either somatic mutations or genetic transformation/regeneration schemes.