Comparative Proteomic Analysis of Self‐Compatible Turnera Mutants Suggests Glutathione S‐Transferase 8 Is Involved in Overcoming S‐Morph Female Self‐Incompatibility Response

Distyly is a reproductive system, characterized by the presence of two floral morphs, which promotes outcrossing via physical and biochemical means. In distylous Turnera , the mating type of the S‐morph is determined by two genes: YUC6 (male) and BAHD (female). Despite the importance of these S ‐genes, it is likely that additional genes are involved in the distylous syndrome. Here, we use comparative mass spectrometry analysis to identify differentially expressed proteins in a series of self‐compatible mutants and wildtype distylous members of Turnera . Our analysis identified a member of the Glutathione S‐transferase family that overwhelmingly correlated with L‐morph male mating type. Exploration of the large datasets and previously published work led to the proposal that differential ROS levels in the pistil may contribute towards the self‐incompatibility response. To support this hypothesis, we generated a co‐expression network for whole flower buds from self‐compatible and WT Turnera joelii . This network led to the identification of a series of ROS and auxin‐related genes that correlated with self‐compatibility. We update previously proposed SI response models to reflect how ROS, jasmonic acid, and brassinosteroid signaling likely establish the S‐morph female self‐incompatibility response. Overall, this work has identified genes potentially related to self‐compatibility and has provided a foundation for future empirical work investigating the basis of the SI response in Turnera .