Browsing by Author "Becker, D."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Cuticular wax composition in Cocos nucifera L.: physicochemical analysis of wax components and mapping of their QTLs onto the coconut molecular linkage map
    (2009) Riedel, M.; Riederer, M.; Becker, D.; Herran, A.; Kullaya, A.; Pena-Rodriguez, L.; Arana-Lopez, G.; Billotte, N.; Rohde, W.; Sniady, V.; Ritter, E.
    Cuticular waxes were extracted from the leaves of a coconut mapping population generated by the controlled cross of an East African Tall and a Rennell Island Tall genotype for the construction of molecular linkage maps. The wax composition was analyzed by capillary gas chromatography/mass spectrometry, and for eight of the wax compounds, their absolute and relative amounts were determined. As reported previously for a different coconut ecotype (Malayan Yellow Dwarf), lupeol methyl ether, isoskimmiwallin, and skimmiwallin were identified as the major components of coconut cuticular wax. The additional compounds were characterized as 3-β-methoxy lupane (lupane methyl ether), lupeol and the acetic acid esters of lupeol, skimmiwallinol, and isoskimmiwallinol, respectively. Minor, nonidentified compounds amounted to some 5% of total wax content and included triterpenoids, sterols, primary alcohols, and fatty acids. The variation detected for parents and progeny with respect to the wax components allowed quantitative trait locus (QTL) analyses for their biosynthetic pathways. A total of 46 QTLs could be mapped onto the coconut linkage map which was extended by amplified fragment length polymorphism and single sequence repeat markers into a high density map with more than 1,000 mapped DNA markers. Several colocated QTLs for different traits were detected reflecting the observed correlations among characters.
  • Thumbnail Image
    Item
    Detection and Molecular Characterization of Phytoplasma associated with Lethal Yellowing Disease of Coconut Palms in Cuba
    (2002) Llauger, R.; Becker, D.; Cueto, J.; Peralta, E.; Gonzalez, V.; Rodriguez, M.; Rohde, W.
    Lethal Yellowing (LY) disease of coconut palm (Cocos nucifera L.) in Cuba has been reported since the end of the 19th century. In order to ascertain the presence of phytoplasmas associated with this disease, leaf samples were taken from plants showing typical disease symptoms and assayed for the LY agent by the polymerase chain reaction (PCR) using LY-specific primers. Selected PCR amplification products were cloned, sequenced and compared to that of a Mexican LY isolate from the Yucata´n region. The results obtained confirm the presence of LY phytoplasma in Cuba. Cuban and Mexican isolates show an overall high degree of sequence similarity with occasional point mutations and small deletions or insertions. Based on these identified genetic differences, LY isolates from the Havana and the Yucata´n region cluster together and apart from isolates originating at Maisı´ in eastern Cuba.
  • Thumbnail Image
    Item
    Linkage mapping and QTL analysis in coconut (Cocos nucifera L.)
    (2000) Herran, A.; Estioko, L.; Becker, D.; Rodriguez, M.J.B.; Rohde, W.; Ritter, E.
    Different DNA marker types were used to construct linkage maps in coconut (Cocos nucifera L.; 2n = 32) for the two parents of the cross Malayan Yellow Dwarf (MYD) × Laguna Tall (LAGT). A total of 382 markers was sufficient to generate 16 linkage groups for each parent. The total genome length corresponded to 2226 cM for the LAGT map and 1266 cM for the MYD map with 4–32 markers per linkage group. Common markers allowed the association of 9 linkage groups for the two parents MYD and LAGT. QTL analysis for the trait early germination identified six loci. These QTLs correlate with early flowering and yield, representing characters which are important in coconut breeding. The co-segregation of markers with these QTLs provides the first opportunity for marker-assisted selection in coconut breeding programmes.