A preliminary characterization of putative leucine-rich repeat (LRR) genes in C. papaya and V. pubescens for PRSV-P resistance
Papaya (Carica papaya L.) as one of the major tropical fruit crops worldwide is limited throughout its growing regions by Papaya ringspot virus type P (PRSV-P). Previous genetic studies identified a functional PRSV-P resistance marker in a mapping population of F2 plants of Vasconcellea pubescens (resistant to PRSV-P) × Vasconcellea parviflora (susceptible to PRSV-P). The marker was used to identify a region on linkage group 5 of the papaya genome sequence. A serine threonine protein kinase (STK) gene that codes for important proteins responsible for defence signal transduction related to resistance of a range of plant pathogens including viruses was sequenced in both C. papaya and V. pubescens. Differences in gene sequence between the two species may show why the two species differ in their response to PRSV-P infection. In addition to the role of STK, the domains of leucine-rich-repeat (LRR) proteins which have a known function to detect pathogen effectors and can work in association with STK genes in plant resistance mechanisms were characterized. It was hypothesized that cloned resistance genes from V. pubescens could be used to develop transgenic papaya that would be resistant to PRSV-P. The putative resistance genes characterized in this research are leading towards an understanding of PRSV-P resistance in V. pubescens and the development of a new source of PRSV-P resistance in papaya genotypes.
Plant Biology not elsewhere classified