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Bhaskar Bondada

., 2010 ; Krasnow et al., 2009 ). In a given block, yield loss can be up to 50% ( Bondada et al., 2009 ). What precisely causes such physiological, biochemical, and structural changes are not known. In the context of climate change scenarios ( Jones et al

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Steven C Wiest and Edward W. Hellman

Scanning electron micrographs of grape berry surfaces, which resemble mountainscapes, contain a wealth of structural information. A typical statistical characterization of features such as root mean square peak-to-peak spacings, peak density, etc., is readily performed on these images. However, a much richer base of information is accessible by analyzing the images with fractal geometry. Fractal box dimension is a quantitative measure of surface roughness, and varies with the contour at which it is determined in both cultivars `Foch' and `Perlette', suggesting that the surfaces are multifractal structures. Fourier spectral analyses of the surfaces produce a similar conclusion. Thus, the unambiguous quantitative resolution of cultivars on the basis of their wax surface structure looks promising, but requires further work.

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Qin Chen and Hai Y. Li

An improved method is described for the isolation of potato metaphase chromosomes for karyotypic and cytogenetic studies. Root tips from diploid Mexican species, Solanum pinnatisectum (2n = 2x = 24) and tetraploid cultivated S. tuberosum (2n = 4x = 48) were given four different pretreatments. The synthetic pyrethroid, Ambush, was the most stable and effective pretreatment reagent, providing the highest percentage of mitotic chromosomes at metaphase and the best spread of countable chromosomes for cytogenetic studies. Compared with an Ambush pretreatment at concentrations of 100-400 ppm, 1 to 10 ppm Ambush produced more easily distinguished chromosomes, which can be useful for comprehensive observation and karyotype analysis in both 2x and 4x potato species. This improved technique for examining mitotic chromosomes will be helpful in describing karyotypes, characterization of new hybrids, and identifying chromosome structural changes that are important in breeding schemes.

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Ping Lang, Can-kui Zhang, Fenny Dane, Shasha Meng, Robert Ebel, and Narendra Singh

Commercial citrus species, some of the most important fruit crops worldwide, are sensitive to sub-freezing temperatures. Poncirus trifoliata, a species closely related to commercial citrus and tolerant to –30 °C, has been used in breeding programs or as a rootstock to impart greater freeze tolerance. Gene expression of P. trifoliata and C. unshiu (Satsuma mandarin) were investigated and compared under slow and fast cold-acclimation regimes. The mRNA differential display-polymerase chain reaction (DDRT-PCR) and cDNA-AFLP, coupled with quantitative relative RT-PCR or real-time PCR were used. Many unique gene fragments were isolated and found to be up- or down–regulated as a result of exposure to low temperature. The up-regulated fragments in Poncirus show high similarities to genes involved in osmotic regulation (betaine/proline transporter, water channel protein, and nitrate transporter), oxidative stress (aldoketo reductase, early light induced protein), and protein interaction (tetratricopeptide-repeat protein, F-box protein, and ribosomal protein L15). In C. unshiu the up-regulated genes show high similarities to genes involved in transcription (zinc finger and GTP-binding protein-related), signal transduction (14–3–3 protein and extension-like protein), protein synthesis and amino acid translocation (permease and ribosomal proteins), chromosome folding (chromosome condensation, structural maintenance of chromosomes-like protein), and carbohydrate metabolism (glycosyl transferase). Several genes involved in photosynthesis, defense and cell wall metabolism were down regulated. Characterization of cold responsive genes will be discussed.

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Paola S. Cotroneo, Maria P. Russo, Manuela Ciuni, Giuseppe Reforgiato Recupero, and Angela R. Lo Piero

Genes encoding chalcone synthase (CHS), anthocyanidin synthase (ANS), and UDP-glucose-flavonoid 3-O-glucosyltransferase (UFGT), some of the enzymes of anthocyanin biosynthetic pathway, were assayed in two different experiments using quantitative real-time reverse transcriptase (RT)-PCR, in order to test their transcription levels in the flesh of blood and common orange [Citrus sinensis (L.) Osbeck] fruit, and to investigate their role in anthocyanin accumulation in the same tissue. The first experiment compared a blood orange and a common orange cultivar during seven different fruit maturation stages. This was followed by the test of 11 different genotypes at the end of the winter season. Data collected from the first experiment, over the blood orange cultivar, were statistically analyzed using the Pearson correlation coefficient. Results show that CHS, ANS, and UFGT mRNA transcripts are up- and co-regulated in the blood orange cultivar, whereas they are down-regulated in the common orange cultivar. There is evidence of correspondence between the target genes expression level and the content of the pigment assessed. The second test confirms this correlation and shows that enzyme synthesis levels and pigment accumulation, in plants grown under the same environmental conditions, are dependent on the differences occurring among the genotypes tested. These results suggest that the absence of pigment in the common orange cultivars may be caused by the lack of induction on the structural genes expression. This is the first report on the characterization of the relationships between biosynthetic genes expression and fruit flesh anthocyanin content in blood oranges.

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Carmina Gisbert, Judith M. Dumm, Jaime Prohens, Santiago Vilanova, and John R. Stommel

elucidated and considerable research has focused on structural and regulatory genes responsible for tissue- and developmental-specific gene expression. Anthocyanin structural gene transcription is dependent on the expression of at least one member of each of

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Yanjie Wang, Yeqing Chen, Man Yuan, Zeyun Xue, Qijiang Jin, and Yingchun Xu

sequences, cDNA clones of seven flavonoid biosynthetic structural genes including NnCHS , NnCHI , NnF3H , NnF3′H , N nF3′5′H , NnDFR , and NnANS were obtained from petals of ZGH with PCR, and the open reading frame (ORF) sequences of these genes were

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John R. Stommel, Gordon J. Lightbourn, Brenda S. Winkel, and Robert J. Griesbach

developmental-specific expression exhibited by anthocyanin structural genes is controlled by regulatory genes. A common set of proteins, comprised of MYB and bHLH MYC proteins plus WD40 repeat proteins, interact to form a regulatory complex that controls

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Hongmei Ma, Margaret Pooler, and Robert Griesbach

working hypothesis was proposed for activation of anthocyanin structural genes by the triad of MYB, MYC, and WDR proteins ( Ramsay and Glover, 2005 ). In a functional MYB-MYC-WD complex, the MYB factor binds directly to the cis-element of the structural

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Antar Nasr El-Banna, Mohammed Elsayed El-Mahrouk, Mohammed Eraky El-Denary, Yaser Hassan Dewir, and Yougasphree Naidoo

germplasm characterization and genetic maintenance. The 310 RAPDs were used to estimate relationships among the accessions. The similarity coefficient based on RAPD patterns ranged from 0.00 to 0.11 ( Table 3 ). Hence, genetic similarity between palm