English walnut (Juglans regia) is a crop plant of increasing economic importance in the world. It is valued for its fruit, timber and medicinal properties[1,2,3].
Aceria erinea (family Eriophyidae) is one of the main and most difficult to control pests of English walnut[4]. Arachnids from this family feed on a wide range of crops and are responsible for serious damage to agriculture. Their feeding induces development of galls on different plant organs, contributing to the decrease of plant fitness and thereby reducing yield.
Galls are structures that facilitate feeding of mites. They are formed solely from plant tissues[5,6]. So far, little is known how mites "urge" the host plant to create a completely unusual structure that acts as a shelter and feeding site for the pest. A. erinea induces a specific type of plant gall - erineum, which is a bulge in the leaf blade filled with epidermal trichomes[5,7].
RNA sequencing data reveal that there are many differentially expressed genes and changes in biological processes, e.g. cell cycle, cell wall formation or nutrients transportation during formation of erineum. The results may help find factors underlying plants’ susceptibility to mites attack and help produce plants with a reduced susceptibility to this group of pests. It will also reduce the amount of pesticides released into the environment.