Heterodichogamy in plants

Dichogamy - a term coined by Sprengel as “Dichogamie” refers to a temporal separation of sexual functions
Individual bisexual flowers begin anthesis with a functionally male or female phase and continue anthesis with both sexes or only the other sex functional
In the case of unisexual flowers, flowering begins with one sex, and the other sex comes later
In flowers of an individual or a population, the functionally male and female phases are often synchronized
 As complete synchronization without overlapping male and female phases in a population would not only exclude cross-pollination, but all pollination, such synchronization needs to be combined with further elaborations that circumvent this disadvantage. 
The simplest pattern is slightly overlapping male and female phases, as reported, e.g. for Anaxagorea dolichocarpa

1. Heterodichogamy in Plants GPB 605 ADVANCES IN PLANT BREEDING (2+0) SUBMITTED BY  Ananda Lekshmi L ID No. 2020608005

2. INTRODUCTION

3. Cont... Study flowers of  Kingdonia   uniflora , an isolated endemic of China, that it posesses heterodichogamous flowers with protandrous and protogynous morphs that have a 1 : 1 ratio.  Flower of Alpinia bracteata showing an upword curved style. At around noon, this style will begin to curve downwards, bringing the stgma into a position where it will contact incoming bees and receives pollen.

4. DICHOGAMY AND HETERODICHOGAMY Dichogamy - a term coined by Sprengel as “ Dichogamie ” refers to a temporal separation of sexual functions Individual bisexual flowers begin anthesis with a functionally male or female phase and continue anthesis with both sexes or only the other sex functional In the case of unisexual flowers, flowering begins with one sex, and the other sex comes later In flowers of an individual or a population, the functionally male and female phases are often synchronized  As complete synchronization without overlapping male and female phases in a population would not only exclude cross-pollination, but all pollination, such synchronization needs to be combined with further elaborations that circumvent this disadvantage.  The simplest pattern is slightly overlapping male and female phases, as reported, e.g. for Anaxagorea dolichocarpa

5. DIFFERENT STRUCTURAL AND TEMPORAL KINDS OF HETERODICHOGAMY AND RELATED PATTERNS (DUODICHOGAMY, PSEUDOHETERODICHOGAMY) Heterodichogamy was first reported by Delpino   for Juglans regia L .  The term was apparently coined by Errera & Gevaert   as “ hétérodichogamie ” In heterodichogamy , male and female functional stages behave in a way that cross-pollination between the same morphs is excluded throughout the flowering season or part of it.  At the transition between the different flowering phases there can be a short overlap of the two functions (during which cross-pollination is possible) or  a neutral, functionless phase (during which, as in the more common case of a smooth transition between the two phases, cross-pollination is prevented)  Juglans regia L . (Walnut)

6. Classification of Heterodichigamy   (1) Temporally, the change in the sex function occurs only once per vegetation period.  (1a) Structurally, the flowers are bisexual (e.g. Trochodendron Siebold & Zucc .). (1b) Structurally, the flowers are unisexual (e.g. Juglans L.).  (2) Temporally, the change in the sex function occurs in a regular pattern many times per flowering period.  (2a) Structurally, the flowers are bisexual (e.g. Alpinia Roxb .).  (2b) Structurally, the flowers are unisexual (e.g. Hernandia L.).  In addition to heterodichogamy , there are cases in which the synchronization mechanism is not based on genetic dimorphism.  Similar patterns of synchrony can also come about without the presence of two reciprocal genetic morphs, but by a specific temporal behaviour of a single morph.

7. (II) Duodichogamy   Term coined by Stout    the two phases come about without two genetic morphs by alternating periods of several days of the same phase three or more times during a flowering season , but they are of irregular length. In the simplest case there are 1½ cycles, mostly with a sequence of male—female— male or, more rarely, female—male—female phases of flowering of functionally unisexual or bisexual flowers in an inflorescence Duodichogamy was first found in the Apiaceae , in which the dichogamous bisexual flowers in an umbel are synchronized and the phase changes occur when umbels of the next higher branching order begin to bloom (Müller, 1873). Apiaceae  or  Umbelliferae  is a family of mostly aromatic flowering plants. Economically important plants such as  carrot, celery, cariander , cumin etc.

8. Mostly,  duodichogamy   occurs in small-flowered,   richly-branched inflorescences  with unisexual or bisexual flowers.  It is especially  frequent in the Sapindales , such as the  Sapindaceae Synchronization cycles with several or numerous phase changes are quite common (in the Sapindales and the  Apiales ), such patterns with multiple phase changes were called  multi-cycle dichogamy  by Lloyd & Webb (1986)  (III).  Pseudoheterodichogamy   It resembles  heterodichogamy  but most probably has only one genetic morph . The two phases come about without two morphs by repeated flushes of flowering within individuals with always one or two flowerless days in between.  In contrast to  duodichogamy , the male and female phases alternate in a daily rhythm coordinated with the day-night rhythm .   Pseudoheterodichogamy  is known from   Eupomatia   laurina   R.Br . ( Eupomatiaceae ) (Endress, 1984) and from a few  Annonaceae

9. TEMPORAL AND STRUCTURAL FRAMEWORK FOR THE EVOLUTION OF HETERODICHOGAMY AND RELATED PATTERNS OF FLOWERING Annual rhythm  The temporal framework is provided by the annual rhythm of the climate and by the daily rhythm between day and night.  The annual rhythm is used in heterodichogamous Fagales (prominently in the Juglandaceae), which have unisexual flowers, flower in spring and are wind pollinated.  In individuals of one morph the male flowers start blooming earlier than the female flowers, and in the second morph they behave the other way around,  Daily rhythm The daily (day-night) rhythm (combined with the annual rhythm) provides the framework for the majority of groups with heterodichogamy and related patterns.  A daily rhythm allows a daily alternation of functional sexes in the flowers , which is realized in the majority of cases with a daily rhythm of flowering.  A prominent clade of this category are magnoliids, in which this behaviour is known from five families out of three orders ( Magnoliales , Laurales , Canellales ).

10. CONCLUSIONS AND PROSPECTS 

11. Reference  Susannae  S. Renner. Trends in Ecology and Evolution Vol.16 No.11 November 2001 Risa D. Sargent* and Sarah P. Otto. A phylogenetic analysis of pollination mode and the evolution of dichogamy in angiosperms. Evolutionary Ecology Research, 2004, 6: 1183–1199 PETER K. ENDRESS. Structural and temporal modes of heterodichogamy and similar patterns across angiosperms. Botanical Journal of the Linnean Society, 2020, 193, 5–18. SHUNTARO WATANABE, NAOHIKO NOMA and TAKAYOSHI NISHIDA

12. Thank you........