Descripción: |
The NPR1(non-expressor of pathogenesis related gene 1) gene
was initially identified in Arabidopsisas a master regulator
of the systemic acquired resistance (SAR). Five additional
NPR1homologues have been identified in Arabidopsiswhose
function range from regulators ofSAR to plant development.
In the present study, we characterized the structure, phylogeny
and expression of the NPR1 family in papaya (Carica papaya
L.), one of the most important tropical fruit crops. We identified four NPR1homologues in the papaya genome sequence
(CpNPR1to CpNPR4). Overall, the fourpapaya predicted
NPR1 proteins showed the characteristic BTB/POZ and ankyrin domains of the ArabidopsisNPR1 family. Twelve additional
open reading frames showing homology to retrotransposon elements or genes involved in different physiological processes
were found in close proximity to the papaya NPR1
homologues. The phylogenetic analysis revealed that the papaya NPR1 sequences resolved in three clades, each clade containing two ArabidopsisNPR1 homologues involved either in
the positive regulation of SAR (clade I), negative regulation
of SAR (clade II) or plant development (clade III), suggesting
a similar function for the corresponding papaya NPR1
homologues. Furthermore, the expression of the four papaya
NPR1homologues was detected in both vegetative and reproductive tissues. The present study has provided the first
comparative analysis of the NPR1family in a tropical fruit
crop and expanded our knowledge on this type of genes in
dicotyledoneous plants. The identification of the full set of
papaya NPR1homologues will pave the way for their systematic functional analysis and new opportunities for engineering disease resistance in this crop. |