Convolvulaceae In Meyler's Side Effects of Drugs (Sixteenth Edition), 2016

Self-Fertilization

V.E. Franklin-Tong, in Brenner's Encyclopedia of Genetics (Second Edition), 2013

Sporophytic Self-incompatibility

SSI is found in the Brassicaceae, Asteraceae, Convolvulaceae, Betulaceae, Caryophyllaceae, Sterculiaceae, and Polemoniaceae. Most molecular analysis of SI has been carried out in Brassica, and its relative, Arabidopsis lyrata. The female S-determinant is a serine/threonine receptor kinase, called S-locus receptor kinase (SRK), which is located at the plasma membrane of the stigmatic cells. It has an extracellular domain that is highly polymorphic between haplotypes, as expected for a specificity-determining protein. The male S-determinant is a member of a large family of small, cysteine-rich proteins, located in the pollen coat, and is called either S-locus cysteine-rich (SCR) or SP11. It acts as a secreted signaling ligand and has been shown to interact with the extracellular region of SRK. Another protein kinase, M-locus protein kinase (MLPK), that is not located at the S-locus also participates in mediating the SI response, and is thought to enhance the signal produced by the male–female S-determinant interaction. Thus, this SI system utilizes a receptor–ligand signaling system to achieve inhibition of pollen that is recognized as ‘self’. The signal, which is produced at the stigma surface, has to be transmitted to cause inhibition of self-pollen and how this is achieved has been elusive. An arm repeat-containing (ARC1) protein, which is an E3 ubiquitin ligase, has been identified as a downstream target involved in the SI response. A component of the exocyst complex, Exo70A1, involved in regulating polarized secretion has recently been shown to be required in the stigma for the acceptance of compatible pollen. As this is negatively regulated by SI, this begins to provide the first insights into the mechanisms potentially involved in regulating self-pollen rejection in this system.