Collagen type XV regulation via MMP2-dependent degradation governs ovarian development in the rice stem borer, Chilo suppressalis.

Female reproductive development is fundamental to the remarkable reproductive capacity of insects, and extracellular matrix (ECM) remodeling plays a critical role in ovarian development. However, the function of Collagen, a major ECM component, in female insect ovarian development remains poorly characterized. Using the major rice pest Chilo suppressalis as a model, we investigated the role of Col XV in insect reproduction. We cloned and characterized Cscol15, a gene encoding a 1077-amino acid protein. Real-time quantitative PCR analysis revealed peak Cscol15 expression during the egg stage and was significantly higher in the head of female pupae compared to other examined tissues. RNAi-mediated knockdown of the Cscol15 gene in female C. suppressalis pupae severely disrupted ovarian development, manifesting as reduced ovarian length and width, decreased vitellogenin deposition, and lower collagen fiber abundance. To further validate these findings, we employed CRISPR/Cas9-mediated knockout of Cscol15, which confirmed that its loss impairs ovarian development and significantly compromises female fertility in C. suppressalis.As a key regulator of collagen synthesis and degradation, we further investigated the role of MMP2 in regulating Collagen XV. Our analysis revealed that overexpression of CsMMP2 reduced the level of Collagen XV, thereby impairing insect reproductive capacity. These findings establish Collagen XV as a key ECM component, likely directly degraded by MMP2. This mechanism governs ovarian morphogenesis in C. suppressalis, positioning Collagen XV as a promising target for reproductive disruption in pest management strategies.