Single-cell transcriptome sequencing reveals that induces gene expression changes in ovary cells to favor its own maternal transmission.

is an obligate endosymbiont that is maternally inherited and widely distributed in arthropods and nematodes. It remains in the mature eggs of female hosts over generations through multiple strategies and manipulates the reproduction system of the host to enhance its spreading efficiency. However, the transmission of within the host's ovaries and its effects on ovarian cells during oogenesis, have not been extensively studied. We used single-cell RNA sequencing to comparatively analyze cell-typing and gene expression in ovaries infected and uninfected with . Our findings indicate that significantly affects the transcription of host genes involved in the extracellular matrix, cytoskeleton organization, and cytomembrane mobility in multiple cell types, which may make host ovarian cells more conducive for the transmission of from extracellular to intracellular. Moreover, the genes and , which are related to the synthesis of ribonucleoprotein complexes, are specifically upregulated in early germline cells of ovaries infected with , revealing that can increase the possibility of its localization to the host oocytes by enhancing the binding with host ribonucleoprotein-complex processing bodies (P-bodies). All these findings provide novel insights into the maternal transmission of between host ovarian cells.IMPORTANCE, an obligate endosymbiont in arthropods, can manipulate the reproduction system of the host to enhance its maternal transmission and reside in the host's eggs for generations. Herein, we performed single-cell RNA sequencing of ovaries from and observed the effects of (strain Mel) infection on different cell types to discuss the potential mechanism associated with the transmission and retention of within the ovaries of female hosts. It was found that the transcriptions of multiple genes in the ovary samples infected with are significantly altered, which possibly favors the maternal transmission of . Meanwhile, we also discovered that may flexibly regulate the expression level of specific host genes according to their needs rather than rigidly changing the expression level in one direction to achieve a more suitable living environment in the host's ovarian cells. Our findings contribute to a further understanding of the maternal transmission and possible universal effects of within the host.