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Ashok K. Ghosh, Lewis N. Lukens, David M. Hunter, and Judith N. Strommer

The genus Pyrus (pear) includes species and cultivars of great diversity. We have tested the feasibility of a polyacrylamide gel eletrophoresis (PAGE)-based +/– simple sequence repeat (SSR) screen as a means of defining relationships amongst pears of commercial importance in North America. The screen included 28 pear accessions, including economically important cultivars, numbered selections from breeding programs and interspecific hybrids. It relied on 18 SSR primer pairs, each of which produced polymorphic banding patterns in all the genotypes examined. Fragments were scored for presence or absence within genotypes. The results show that amplification and analysis of a small number of SSR loci enable identification of cultivars and reasonable definition of genetic relationships in North American pears. Seven primer pairs were sufficient to distinguish the 28 pear cultivars. Analyses using both distance and parsimony criteria grouped cultivars in a manner consistent with known pedigrees and sites of origin.

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Maureen C. O'Leary and Thomas H. Boyle

Polyacrylamide gel electrophoresis was used to study inheritance and linkage of isozymes in Easter cactus (Hatiora species and interspecific hybrids). Five isozyme systems were analyzed: aspartate aminotransferase (AAT), glucose-6-phosphate isomerase (GPI), malate dehydrogenase (MDH), phosphoglucomutase (PGM), and triosephosphate isomerase (TPI). F1, F2, BC1, and S1 progeny were used for inheritance studies. Six polymorphic loci (Aat-1, Gpi-1, Mdh-1, Pgm-1, Pgm-2, and Tpi-2) were identified. Aat-1 and Pgm-1 were linked (recombination frequency = 26% ± 7%), but the other isozyme loci assorted independently. Aberrant segregation ratios were observed in at least one segregating family for all six isozyme loci. We hypothesize that segregation distortion was due to linkage between isozyme loci and other genes subject to pre- or postzygotic selection. The existence of five additional isozyme loci (Aat-2, Gpi-2, Mdh-2, Mdh-3, and Tpi-1) was inferred from segregation patterns and by comparison of isozyme profiles from phylloclades and pollen. These isozyme loci may prove useful for confirming hybridity in intra- and interspecific crosses, determining parentage of cultivars, and assessing genetic diversity in germplasm collections.

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Teresa A. Morrison, Russell Pressey, and Stanley J. Kays

Staple-type lines of sweetpotato [Ipomoea batatus (L.) Lam.] do not sweeten significantly upon cooking as compared to the traditional-type lines. Four lines exhibiting distinct differences in sweetness after cooking were evaluated for changes in α- and ß-amylase activity and reducing sugars (by HPLC) at harvest, after curing, and at intervals during 180 days of storage. The traditional cultivar `Jewel' and staple-type line `Sumor' displayed high a- and ß-amylase activities, which rose from low levels at harvest to peak levels ≈ 90 days into the storage period. Staple-type lines `99' and `86' displayed significantly lower a- and ß-amylase activities. By using polyclonal sweetpotato ß-amylase antibody and western blot following native- and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, it was confirmed that a lower level of ß-amylase synthesis existed in `99' and `86'. Quantitatively, `Jewel', `Sumor', and an additional staple-type line, `HiDry', had 361,374, and 365 μg ß-amylase protein per gram of fresh storage root tissue, respectively, while `99' and `86' possessed <60 and 12 μg·g-1, respectively. In raw roots, individual (glucose, fructose, and sucrose) and total sugar concentrations were significantly higher in `Jewel' than in `Sumor', `99', or `86'. Only trace amounts of maltose were found in raw roots of any line. Sucrose, glucose, and fructose concentrations decreased with baking in all lines except `86', in which they increased. There was substantial maltose produced by baking `Jewel' and `Sumor', but only trace amounts found in baked `99' and `86'. Sweetpotato germplasm can be separated into four general classes based on initial sugar concentration and changes during cooking: 1) low sugars/low starch hydrolysis, 2) low sugars/high starch hydrolysis, 3) high sugars/low starch hydrolysis, and 4) high sugars/high starch hydrolysis. At least two mechanisms may confer the lack of starch hydrolysis and subsequent sweetening in staple-type sweetpotato: 1) inhibition of ß-amylase synthesis, and 2) a nonenzyme mediated mechanism.

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Clíssia Barboza da Silva, Julio Marcos-Filho, Pablo Jourdan, and Mark A. Bennett

staining for peroxidase in bell pepper seeds of two cultivars, AF-6 and AF-7, following nondenaturing polyacrylamide gel electrophoresis. Each cultivar was represented by three and four seed lots, respectively. (a) Unprimed seeds; (b) drum-primed seeds

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Franco Famiani and Robert P. Walker

western blotting of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in conjunction with specific antisera, an approach that has proved successful for a number of soft fruit ( Famiani et al., 2005 , 2009 ). To use this approach, it is

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Akiko Watari, Toshio Hanada, Hisayo Yamane, Tomoya Esumi, Ryutaro Tao, Hideaki Yaegaki, Masami Yamaguchi, Kenji Beppu, and Ikuo Kataoka

cDNA quantities of S-RNase and SFB were normalized using the ACTIN cDNA values and compared as relative amounts of their transcripts. Two-dimensional polyacrylamide gel electrophoresis analysis of pistil proteins. Acetone powders were

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Yiming Liu, Hongmei Du, Kai Wang, Bingru Huang, and Zhaolong Wang

. However, Fv/Fm of seashore paspalum decreased significantly after 8 d under the 500-m m treatment and reached 90.7% of the control at the end of the experiment (32 d). Sodium dodecyl sulfate–polyacrylamide gel electrophoresis for protein changes during

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Madhurababu Kunta, J.V. da Graça, and Mani Skaria

( Roistacher et al., 1973 ; Vogel and Bové, 1976 ) followed by sequential polyacrylamide gel electrophoresis (sPAGE). This is a standard, sensitive method but there are some disadvantages, for example, biological indexing on Etrog citron requires 3 to 6 months

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Chang-Xia Du, Huai-Fu Fan, Shi-Rong Guo, and Takafumi Tezuka

nm. One unit of CAT activity was defined as the amount of enzyme required to decrease the optical density at 240 nm·min −1 by 0.1 absorbance units. Native polyacrylamide gel electrophoresis (PAGE) was performed at 100 V for 60 min at 4 °C, and then

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Ettore Barone, Luigi Di Marco, Francesco P. Marra, and Maria Sidari

Canonical discriminant analysis (CDA) of morphometric data of buds, leaves, and fruit, as well as isozyme analysis (esterase, peroxydase, and acid phosphatase) of leaf samples, were used to identify eight male pistachio selections and 10 female pistachio cultivars. According to the CDA, 77% and 93% of the total variance was summarized by the first three canonical discriminant functions for the female and male selections, respectively. Fruit characteristics, particularly fruit fresh and dry weights and fruit length, accounted for most of the discriminatory power for the female cultivars, while the dimensions of the leaves, principally leaf rachis length, were the most effective discriminating characters for the males. Isozyme analysis showed a higher degree of polymorphism in the male than the female genetic pool. Hence, using only three enzymes, it was possible to identify all of the male selections, but only 50% of the females. Peroxidase polymorphism clearly demonstrated the greater phylogenetic distance between `Kerman' and the local cultivars, as well as between `Cerasola', a quite different cultivar with a reddish hull, and the others tested. The combination of CDA and isozyme analysis enhanced the possibility of uniquely identifying the female cultivars.