Carob (Ceratonia siliqua L.) is a caesalpinoid legume tree showing labile sex expression. With the main aims of identifying flower-expressed genes
and of developing specific markers, 1,056 clones from a complementary DNA library of carob flowers were bidirectionally sequenced.
A total of 1,377 high-quality expressed sequence tags were clustered into 1,096 unigenes. Basic Local Alignment Search Tool
and Gene Ontology functional annotation allowed to identify several agronomically important genes, such as those involved
in flower development and sexual reproduction, response to stress, galactomannan synthesis, and hormone pathways. Genes involved
in the ethylene biosynthesis and response were quantified in developing flowers of three sex genotypes (male, female, and
hermaphrodite) using quantitative reverse transcription polymerase chain reaction. The transcript levels of 1-aminocyclopropane-1-carboxylic
acid oxidase, acting downstream in ethylene pathway, and Ethylene Insensitive 3 (EIN3)-like, a transcription factor involved
in ethylene signaling, were directly correlated with maleness, indicating a possible role of ethylene in carob sex expression.
Furthermore, the first set of carob genic microsatellites was developed, which might be useful for genotyping and genetic