Melon downy mildew caused by Pseudoperonospora cubensis leads to significant losses in melon yields worldwide. Reverse-transcription Polymerase Chain Reaction （RT-PCR） was performed using cDNAs as templates from mel...Melon downy mildew caused by Pseudoperonospora cubensis leads to significant losses in melon yields worldwide. Reverse-transcription Polymerase Chain Reaction （RT-PCR） was performed using cDNAs as templates from melon-Huangdanzi induced with fungus Pseudoperonospora cubensis, and degenerate primers designed based on the conserved amino acid sequences of known plant disease-resistance genes. A polymorphic cDNA fragment which we named rap-19 was cloned and sequenced. The Open Reading Frame （ORF） of this product comprised of 510 base pairs which encodes DNA or RNA-binding protein with 170 amino acids. The putative amino acid sequence of mp-19 appeared highly homologous with those of NBS-type resistant-genes isolated from other plants. Southern blot indicated that the melon genome contained more than 3 copies of rap-19. The obvious expression differences detected by semi-quantitative RT- PCR could be observed between resistant-line Huangdanzi and susceptible-line Jiashi after Pseudoperonospora cubensis infection, which implied that mp-19 gene may be related to the resistance of downy mildew in melon.展开更多
基金This study was supported by the Natural Science Foun-dation of Xinjiang Uygur Autonomous Region, China(200121105)Science and Research Plan Emphasis Project of College in Xinjiang Uygur Autonomous Region, China (XJEDU2004I09).
文摘Melon downy mildew caused by Pseudoperonospora cubensis leads to significant losses in melon yields worldwide. Reverse-transcription Polymerase Chain Reaction （RT-PCR） was performed using cDNAs as templates from melon-Huangdanzi induced with fungus Pseudoperonospora cubensis, and degenerate primers designed based on the conserved amino acid sequences of known plant disease-resistance genes. A polymorphic cDNA fragment which we named rap-19 was cloned and sequenced. The Open Reading Frame （ORF） of this product comprised of 510 base pairs which encodes DNA or RNA-binding protein with 170 amino acids. The putative amino acid sequence of mp-19 appeared highly homologous with those of NBS-type resistant-genes isolated from other plants. Southern blot indicated that the melon genome contained more than 3 copies of rap-19. The obvious expression differences detected by semi-quantitative RT- PCR could be observed between resistant-line Huangdanzi and susceptible-line Jiashi after Pseudoperonospora cubensis infection, which implied that mp-19 gene may be related to the resistance of downy mildew in melon.
