| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 103 === To explore whether interactions exist between Papaya Ringspot Virus (Papaya ringspot virus; PRSV) and papaya ( Carica papaya L. ) varieties in order to provide important information for PRSV resistance breeding. Three varieties were inoculated with six isolated virus strains. Forty days after inoculation in the greenhouse, SMN (severe mottling with necrosis) strain and the strain from Jiayi resulted in the most severe symptoms whereas minor symptoms were observed from the Pintung strain. Different virus strains showed different symptoms. For example: SMN caused rapid wilting, Jiayi developed serious deformity. The degree of virus resistance among varieties showed significant differences. AUPDC also exhibited significant differences between different virus isolates (PRSV). Strategies for disease resistance breeding are influenced by the major effects and interactions between viruses and varieties. Accumulating the number and diversity of resistant genes will be essential to the stabilization of PRSV-resistant varieties. Papaya petiole color may be purple or green. Purple color which is controlled by P allele is dominant to green color. The petioles observed in the field showed different shades of purple. To verify the genetic model for petiole color, this experiment analyzed petiole colors in purple line P1, green line P2, Hybrid F1, F2 and backcross BC. The result indicated complete dominance of purple to green for P gene. The offspring of Pp x Pp showed dark purple, light purple, and green with 1:2:1 ratio as confirmed by χ2 . The offspring of Pp x pp only showed light purple and green petiole inferring incomplete dominance for P allele. P-locus showed incomplete dominance resulted in different shades of purple for papaya.
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