Trimonoecy
Sexual system in flowering plants
From Wikipedia, the free encyclopedia
Trimonoecy, also called polygamomonoecy or androgynomonoecy, is a sexual system in plants in which a single individual produces male, female, and hermaphroditic flowers simultaneously.[1] Trimonoecy is rare,[2] occurring in 0.025% of angiosperm species.[3]
It is a monomorphic sexual system along with monoecy, gynomonoecy, and andromonoecy. It is hypothesized that trimonoecy originated from gynomonoecy.[4]
Genetic basis
Ethylene is a master regulator of sex determination in some diclinous plants, such as the cucurbits.[5] In melon and watermelon, sex forms are controlled by three major genes: G/g (gynoecious), A/a (andromonecious) and M/m (male).[6] Mutations in M, which encodes an ACC synthase (ACS) involved in ethylene biosynthesis, causes female flowers to develop into hermaphrodites and the individual to become trimonoecious.[6] Similarly, mutating ACO1A, another ethylene biosynthesis gene, in Cucurbita pepo also promotes the conversion of female flowers to hermaphroditic flowers while male flowers remain unaffected, resulting in partial andromonoecy or trimonoecy.[7]
Prevalence
Trimonoecy is present in 73 species across 44 genera and 29 families of angiosperms; 6.9% of all angiosperm families, including 20.0% of monocot families, are trimonoecious.[3] 80.3% of all trimonoecious species belong to the Superrosids or Superasterids.[3] No evidence of trimonoecy has been found in basal angiosperms or magnoliids.[3]
