Identification of reference genes for qRT-PCR studies of gene expression in giant cells and syncytia induced in Arabidopsis thaliana by Meloidogyne incognita and Heterodera schachtii

Sedentary plant-parasitic nematodes, such as cyst and root-knot nematodes, induce feeding structures in the host root that undergo extensive changes in the gene expression. This phenomenon has previously been studied by gene chip analysis and qRT-PCR. Housekeeping genes are often used routinely as internal references for relative qRT-PCR analyses. However, due to the strong influence of nematode infection on host cell metabolism and physiology, expression of housekeeping genes may be altered considerably, thus limiting reliability of qRT-PCR analyses. Therefore, in the present work we tested UBQ10, ACT2, EF1a, UBP22 and 18S rRNA as potential candidates for relative qRT-PCR studies of gene expression in nematode infection sites in roots of Arabidopsis thaliana. Among the tested candidates only UBP22 and 18S rRNA were stably expressed and, therefore, are reliable reference genes for studying cyst and root-knot nematode infections.