Genome-wide identification and functional characterization of OsLAT52 genes associated with pollen tube growth in rice (Oryza sativa)

Pollen tube (PT) growth is crucial for double fertilization and seed production in angiosperms. Signaling peptides have emerged as major factors in cell-to-cell communication during reproduction. However, the characteristics and functions of these peptides and their receptors remain largely unknown, particularly in rice species. Here, we identified five Oryza sativa late anther tomato 52 (OsLAT52) genes in the rice genome, homologs of tomato LAT52, which are crucial for pollen-pistil interactions through receptor-mediated signaling in tomato. OsLAT52a was the most prominently expressed gene among the five OsLAT52s, and the GFP signal from OsLAT52 accumulated at the tip of the PT in pOsLAT52a:OsLAT52a-eGFP transgenic rice. oslat52a-1 knockout mutants showed normal vegetative growth and development of reproductive organs but exhibited partial male sterility. These mutants exhibited defects in pollen germination and PT elongation, accompanied by reduced reactive oxygen species (ROS) levels in the PTs. Co-immunoprecipitation (Co-IP) assays showed that OsLAT52a interacted with Male-gene transfer defective 2 (MTD2), which belongs to the Catharanthus roseus receptor-like kinase 1-like (CrRLK1L) family. Transcript analysis revealed that genes downstream of OsLAT52a are involved in diverse signaling pathways, redox homeostasis, and cell wall remodeling. Collectively, our findings identify OsLAT52a as a pollen-specific peptide signal that engages CrRLK1L receptor and modulates the ROS balance to ensure proper PT growth in rice.