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- Author or Editor: D. LaBonte x
- Journal of the American Society for Horticultural Science x
Molecular markers linked to resistance to sweetpotato chlorotic stunt closterovirus [SPCSV (genus Crinivirus, family Closteroviridae)] and sweetpotato feathery mottle virus [SPFMV (genus Potyvirus, family Potyviridae)] were selected using quantitative trait loci (QTL) analysis, discriminant analysis and logistic regression. Eighty-seven F1 sweetpotato [Ipomoea batatas (L.) Lam.] genotypes from a cross of `Tanzania' and `Wagabolige' landraces were used to generate DNA marker profiles for this study. Forty-five of the clones were resistant to SPCSV while 37 were resistant to SPFMV. A combination of 232 amplified fragment length polymorphism (AFLP) markers and 37 random amplified polymorphic DNA (RAPD) markers obtained were analyzed to determine the most informative markers. All three statistical procedures revealed that AFLP marker e41m33.a contributed the greatest variation in SPCSV resistance and RAPD marker S13.1130 accounted for most of the variation in SPFMV resistance. The power of discriminant and logistic analyses is that you do not need a parent-progeny population. An evaluation of these two models indicated a classification and prediction accuracy rates of 96% with as few as four markers in a model. Both multivariate techniques identified one important discriminatory marker (e44m41.j) for SPCSV and two markers (e41m37.a and e44m36.d) for SPFMV that were not identified by QTL analysis.
Sweet potato virus disease (SPVD) is the most devastating disease of sweetpotato [Ipomoea batatas (L.) Lam.] globally. It is caused by the co-infection of plants with a potyvirus, sweet potato feathery mottle virus (SPFMV), and a crinivirus, sweet potato chlorotic stunt virus (SPCSV). In this study we report the use of cDNA microarrays, containing 2765 features from sweetpotato leaf and storage root libraries, in an effort to assess the effect of this disease and its individual viral components on the gene expression profile of I. batatas cv. Beauregard. Expression analysis revealed that the number of differentially expressed genes (P < 0.05) in plants infected with SPFMV alone and SPCSV alone compared to virus-tested (VT) plants was only 3 and 14, respectively. However, these findings are in contrast with SPVD-affected plants where more than 200 genes were found to be differentially expressed. SPVD-responsive genes are involved in a variety of cellular processes including several that were identified as pathogenesis- or stress-induced.
Using codominant molecular markers (microsatellites) for paternity identification was investigated in hexaploid sweetpotato [Ipomoea batatas (L.) Lam.]. Two experimental populations (CIP and LAES), each consisting of progeny of known parentage, were scored for the presence or absence of alleles segregating at IB-316 and IB-318 microsatellite loci. Paternity was assessed using paternity exclusion and the most-likely parent methods. In the former, paternity is assigned based on the identification of incompatible parent-progeny marker data. In contrast, the latter method incorporates paternity exclusion and a log-likelihood or LOD score that weighs progeny allelic patterns as to the likelihood that they could have come from a given paternal parent. The number of correctly allocated progeny differed for the methods. Paternity exclusion correctly allocated 7% and 25% of the progeny in the LAES and CIP populations, respectively. The most-likely parent method correctly allocated 23% and 88% of the progeny in the LAES and CIP populations, respectively. The greater misassignments in the LAES population were attributed to low allelic diversity at the LAES IB-318 locus and a larger parental population. This study demonstrates the feasibility of identifying paternity in sweetpotato using a minimal number of loci.