Investigating the expression of bZIP, MPK6, Peroxidase72, MurG, Lipoxigenase, ACC synthase, and ACC oxidase as genes involved in the resistance mechanism of date palm to Oligonychus afrasiaticus

In order to identify the genes involved in the resistance of date palms to spider mite, sampling was taken from three relatively resistant and three susceptible date palm cultivars at the end of July in the Kimmeri stage, simultaneously with mite activity. Then the activity of some genes was investigated with the aim of determine the molecular mechanism of date palm resistance to the spider mite.

After RNA extraction and cDNA synthesis, the expression of 7 genes, including bZIP, MPK6, Peroxidase72, MurG, Lipoxigenase, ACC synthase and ACC oxidase genes, were investigated by qRT-PCR in susceptible and semi-resistant cultivars. In order to design the primers, the selected genes CDS were aligning with the date palm genome and finding related genes by Clustal W then primers were designed using Primer3 databases. After the end of the experiment, the amount of gene transcripts were determined and compared.

The MurG gene showed higher expression in relatively resistant cultivars: Zahedi, Hallawi and Estamaran than susceptible cultivars: Lilwi, Khadrawi and Barhee (Zahidi maximum and Lilwi minimum). The expression of the Peroxidase72 gene in relatively resistant cultivars including Zahedi (100%) and the lowest expression related to susceptible cultivar Lilwi (76.81%). The bZIP gene was found in relatively resistant cultivars including Zahedi (100%) and the lowest expression in the susceptible cultivar Lilwi (78.19%). The Lipoxigenase gene was found in relatively resistant cultivars including Zahedi (100%) and the lowest expression in the susceptible cultivar Lilwi (73.56%). The expression of the ACC synthase gene in relatively resistant cultivars including Zahedi (100%) and the lowest expression was in the susceptible cultivar Lilwi (81.56%). The ACC oxidase gene was in relatively resistant cultivars including Hallawi (100%) and the lowest expression was in the susceptible Lilwi cultivar (85.37%). MPK6 gene expression was observed in all three susceptible cultivars, but no expression was observed for this gene in all three relatively resistant cultivars.

The expression of some genes in susceptible and resistant cultivars followed a regular pattern and the expression of other genes had an irregular pattern. As a result, it can be concluded that the role of MurG and bZIP gene product is up regulating the resistance of date palm to mite, but the role of MAPK6 gene product is down regulating the resistance of date palm to mite.