Diocyte (from ancient Greek δίς dis “twice” and οἰκία oikia “house”) or dioeciousness is a form of separate sex distribution in seed plants . Female and male flowers occur on separate individuals. In the case of mushrooms , one speaks of a diocese if there are two types of mycelia and one of them can only serve as a core donor, the other only as a core recipient.
Diocyte in plants occurs in many plant families, but mostly in low frequency. Few families are entirely diocesan , like the willow family (Salicaceae). Due to the systematic distribution, dioceses often emerged independently of one another.
The angiosperms a dioecious Art. Around seven percent of all genres included at least six percent of all angiosperm species are dioecious. Most of the diocesan genera have exclusively diocesan species, only a third of the genera have more than one sex distribution. Diocese is widespread among the Bedecktsamern, as it occurs in over 40 percent of families .
Diocyte is slightly more common in dicotyledons than in monocotyledons . A particularly large number of diocesan species can be found among the Lauraceae , Menispermaceae , Myristicaceae , Euphorbiaceae , Moraceae and Urticaceae . In general, diocese is more common among the less derived clans than among the more strongly derived.
Characteristics that are more frequently associated with dioceses are in descending frequency: monoecia in related species, climbing habit, spread of the diaspores by animals ( zoochory ), non-animal pollination ( wind and water pollination ), shrubby habit and tropical distribution. Parasites or heterotrophs of various forms make up only four percent of the diocesan genera, in this group, however, diocese is overrepresented with 43 of a total of 135 heterotrophic genera.
Genetic control of the diocese
In most diocesan species, gender expression is determined by sex chromosomes . In most species, the male plants are heterogametic XY and the female are homogametic XX. Exceptions, in which the male plants are homogametic, are about Potentilla fruticosa and the genus Cotula . However, the genetic gender can be influenced by environmental influences.
Diocese is a derived characteristic in seed plants. Many unisexual plants contain rudimentary organs of the opposite sex. The unisexuality arises through the suppression of the formation of the opposite sex: female plants are male-sterile, male plants are female-sterile. Male sterility usually shows itself in the reduction of the anthers to reduced, small staminodes ; female sterility leads to small pistils (pistillodium) in which no ovules are formed.
Sometimes the diocese is also cryptic, that is, the flowers are morphologically hermaphroditic with plenty of pollen- producing stamens and normal-sized ovaries. In some nightshade species ( Solanum ), the female-fertile plants produce non-germinable pollen. Pollen cannot germinate on the stigmas of the plants that produce fertile pollen. The advantage for the plants to still produce sterile pollen or sterile ovaries is explained by the fact that the pollinators visit the flowers better if all the flowers contain pollen and the nectar (produced in the ovaries) .
- Adrian J. Richards: Plant Breeding Systems . 2nd Edition. Chapman & Hall, London 1997, ISBN 0-412-57440-3 , pp. 298-312 .
- Susanne S. Renner , Robert E. Ricklefs : Dioecy and Its Correlates in the Flowering Plants . In: American Journal of Botany . tape 82 , no. 5 , 1995, ISSN 0002-9122 , pp. 596-606 , JSTOR : 2445418 .