Differential Proteomic Analysis to Identify Proteins Associated with Apomeiosis in Boehmeria tricuspis (Hance) Makino Using an iTRAQBased Strategy

Numerous candidate genes related to apomixis have been identified through transcriptomics; however, the molecular mechanism underlying apomixis remains unclear. Elucidation of the underlying mechanisms is essential to expand its application in crop breeding. Therefore, here, we employed the isobaric tags for a relative and absolute quantification labeling technology to investigate the protein expression in Boehmeria tricuspis generated through different reproductive modes at the functional megaspore stage. We identified 40 differential abundance proteins associated with apomeiosis, most of which were involved in "response to stress". Functional analysis suggested that lower levels of reactive oxygen species (ROS) play a role in inducing the development of apomeiosis. Proteins related to ROS regulation, cell wall modifications, and stability under heat stress play a crucial role in the development of diplosporic apomeiosis. Our results give evidence to the insight that stress can induce a switch from apomixis to sexuality by ROS content, and an increased composition of stress tolerance as well as secondary metabolites can buffer ROS effects. Precise coordination of these proteins involved in inter-related regulatory control mechanisms may act together in the transition from the sexual to apomixis development.