Expression of hydroxymethylglutaryl-CoA reductase 2 (HMG2) gene in chilli (Capsicum annuum L.) CM334 infected by nacobbus aberrans and phytophthora capsici

Plants of chilli Capsicum annuum L. CM334 show a high level of resistance to Phytophthora capsici, but are susceptible to Nacobbus aberrans; such resistance has been associated with capsidiol accumulation, a sesquiterpene phytoalexin. In the present study the expression of hydroxymethylglutaryl-CoA reductase 2 gene (HMG2, associated with sesquiterpene phytoalexins biosynthesis) in CM334 chilli roots inoculated with N. aberrans and in combination with P. capsici, was determined by qRT-PCR. The levels of HMG2 transcripts were significantly reduced (p≤0.05) from -1.57 to -1.28-fold in the interaction CM334/N. aberrans; whereas in roots inoculated only with the oomycete, the accumulation of transcripts occurred earlier and at higher levels (1.52 to 3.54-fold). In plants inoculated with both pathogens, the expression was higher compared with those inoculated with the nematode only (p≤0.05), but generally lower than the expression observed in roots of plants inoculated with the oomycete alone. The expression of the HMG2 gene associated with defense was reduced in CM334 chilli plants infected by N. aberrans.