A single PLAT domain protein couples reproductive arrest and carotenoid pigmentation during diapause in the two-spotted spider mite, Tetranychus urticae Koch

Adult females of the two-spotted spider mite, Tetranychus urticae Koch, enter a photoperiodically induced diapause to overwinter. Diapause in T. urticae is accompanied by reproductive arrest and the orange body coloration that arises from the accumulation of astaxanthin esters. How these two traits are coordinated at the molecular level remains poorly understood. Here, we compared the proteomes of adult females reared under diapause-inducing (long-night) and non-diapause-inducing (short-night) photoperiods using liquid chromatography-tandem mass spectrometry, followed by RNA interference (RNAi) of candidate genes. The carotenoid biosynthesis enzymes phytoene desaturase (TuPDS) and lycopene cyclase/phytoene synthase (TuLCPS), both encoded by genes horizontally transferred from fungi, were more abundant in diapausing females than in non-diapausing females. RNAi of the genes encoding TuPDS and TuLCPS markedly reduced orange pigmentation as well as β-carotene and astaxanthin contents, demonstrating that these enzymes are required for diapause-associated pigmentation. Our proteomic analysis further identified a single PLAT (Polycystin-1, Lipoxygenase, Alpha-toxin) domain protein, TuPLAT10, as one of the most strongly upregulated proteins in diapausing females. The PLAT domain is a lipid-binding module, suggesting a role for TuPLAT10 in lipid metabolism. In addition to the suppression of orange pigmentation, RNAi of the TuPLAT10 gene restored reproduction even under diapause-inducing conditions and selectively reduced TuPDS and TuLCPS protein levels, despite the absence of sequence similarity to their genes. We propose that TuPLAT10 acts as a lipid-allocation switch that, in response to photoperiodic information, partitions fatty acids between astaxanthin esterification and yolk lipid supply, thereby coupling reproductive arrest and carotenoid pigmentation during diapause in T. urticae.