Tiny tomato suppressor

Symbiosis Acarid arthropods are common and economically important pests of crop plants. The tomato russet mite Aculops lycopersici is only 175 micrometers long but can potently suppress the host plant's natural resistance. It has a highly streamlined genome of 32.5 megabases, more closely resembling that of a protist than a metazoan. Greenhalgh et al. discovered that this mite leaves no room in its genome for hangers-on. It contains few transposons, has slimmed intergenic spaces to almost none, has almost done away with chemosensory apparatus and detox pathways, and has even reduced its number of legs from eight to four in the interests of economy. However, it has retained the capacity to suppress the tomato's jasmonic acid signaling pathway, which blocks the ability of the tomato host plant to produce defensive metabolites and proteins. However, the selective forces resulting in this genome diminution remain a puzzle—perhaps one is the poor nutritional value of tomato plants. eLife 9 , e56689 (2020).