2 results for Ampomah-Dwamena, C

  • Analysis of expressed sequence tags from Actinidia: Applications of a cross species EST database for gene discovery in the areas of flavor, health, color and ripening

    Crowhurst, RN; Gleave, AP; MacRae, EA; Ampomah-Dwamena, C; Atkinson, RG; Beuning, LL; Bulley, SM; Chagne, D; Marsh, KB; Matich, AJ; Montefiori, M; Newcomb, Richard; Schaffer, Robert; Usadel, B; Allan, Andrew; Boldingh, HL; Bowen, JH; Davy, MW; Eckloff, R; Ferguson, AR; Fraser, LG; Gera, E; Hellens, RP; Janssen, BJ; Klages, K; Lo, KR; MacDiarmid, Robin; Nain, B; McNeilage, MA; Rassam, M; Richardson, AC; Rikkerink, EHA; Ross, GS; Schroder, R; Snowden, KC; Souleyre, EJF; Templeton, Matthew; Walton, EF; Wang, D; Wang, MY; Wang, YY; Wood, M; Wu, RM; Yauk, YK; Laing, WA (2008)

    Journal article
    The University of Auckland Library

    Background: Kiwifruit (Actinidia spp.) are a relatively new, but economically important crop grown in many different parts of the world. Commercial success is driven by the development of new cultivars with novel consumer traits including flavor, appearance, healthful components and convenience. To increase our understanding of the genetic diversity and gene-based control of these key traits in Actinidia, we have produced a collection of 132,577 expressed sequence tags (ESTs). Results: The ESTs were derived mainly from four Actinidia species (A. chinensis, A. deliciosa, A. arguta and A. eriantha) and fell into 41,858 non redundant clusters (18,070 tentative consensus sequences and 23,788 EST singletons). Analysis of flavor and fragrance-related gene families (acyltransferases and carboxylesterases) and pathways (terpenoid biosynthesis) is presented in comparison with a chemical analysis of the compounds present in Actinidia including esters, acids, alcohols and terpenes. ESTs are identified for most genes in color pathways controlling chlorophyll degradation and carotenoid biosynthesis. In the health area, data are presented on the ESTs involved in ascorbic acid and quinic acid biosynthesis showing not only that genes for many of the steps in these pathways are represented in the database, but that genes encoding some critical steps are absent. In the convenience area, genes related to different stages of fruit softening are identified. Conclusion: This large EST resource will allow researchers to undertake the tremendous challenge of understanding the molecular basis of genetic diversity in the Actinidia genus as well as provide an EST resource for comparative fruit genomics. The various bioinformatics analyses we have undertaken demonstrates the extent of coverage of ESTs for genes encoding different biochemical pathways in Actinidia.

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  • Identification and characterisation of primary microRNAs from apple (Malus domestica cv. Royal Gala) expressed sequence tags

    Gleave, AP; Ampomah-Dwamena, C; Berthold, S; Dejnoprat, S; Karunairetnam, S; Nain, B; Wang, YY; Crowhurst, RN; MacDiarmid, Robin (2008)

    Journal article
    The University of Auckland Library

    Microribonucleic acids (miRNAs) are small, non-coding RNAs that play important regulatory roles by down-regulating target transcripts in a sequence-specific manner. The miRBase Registry (Release 8.2) lists 732 miRNAs from flowering plant species, with the majority identified from Arabidopsis, rice and poplar where genome sequence is available. In the absence of genomic sequence and on the basis that sequences of many miRNAs are conserved amongst divergent plant species, we analysed approximately 120,000 Malus domestica cv. Royal Gala expressed sequence tags (ESTs) and identified ten distinct sequences that could be classified into seven conserved plant miRNA families (miR156, miR159, miR162, miR167, miR172, miR393 and miR398). Secondary structure predictions showed these sequences have the characteristic fold-back structures of precursor miRNAs, and northern analysis validated the presence of these miRNA families within Royal Gala tissues. A number of the miRNAs were expressed constitutively in all tissues tested (miR159, miR162 and miR172), while others showed more restricted patterns of expression, being expressed primarily in leaf (miR398), expressed in leaf and floral bud tissue but down-regulated during fruit development (miR156 and miR167) or expressed in fungal pathogen-infected leaf tissue (miR393). Potential targets for six of the miRNA families were identified from the EST dataset and completely sequenced complementary deoxyribonucleic acids. In general, these targets encode proteins shown to be the targets of corresponding miRNAs in other plant species. Demonstrating cleavage of a number of the putative target transcripts within the region of miRNA/messenger RNA complementarity provided further evidence of the functionality of the identified Royal Gala miRNAs.

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