Pollen Tube Content Facilitates and Increases the Potential of Endosperm Proliferation Irrespective of Fertilization in Arabidopsis thaliana

Sexual reproduction in angiosperms is a complex and precise process of regulation, which includes the pollen tube guidance, double fertilization, and the seed development process. The previous report identified that for seed development, there is a period of preparation for fertilization (between pollen tube guidance and double fertilization) that is called pollen-tube-dependent ovule enlargement morphology (POEM). It has been shown that the pollen tube content (PTC) plays a crucial role in the enlargement of ovules and the initiation of seed coat formation. However, we did not investigate the potential of endosperm proliferation in autonomous mutants at a later stage. Here, we investigated this phenomenon using vanillin staining and transparent experi-ments to examine the manner, in which the PTC affects the potential of endosperm formation. Interestingly, the PTC increased the number of endosperm nuclei without fertilization equally and synchronously in mea and fis2 ovules. This finding might help improve the study of apomixes and our understanding of how the molecular mechanisms that regulate this phenomenon will contribute to plant reproductive science in the future.