Identifying and Understanding Pollen Abnormalities: Impacts on Fertility and Viability.pptx

Identifying and Understanding Pollen Abnormalities: Impacts on Fertility and Viability.pptx

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  A SEMINAR REPORTON ABNORMALITIES OF POLLEN
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  Abnormal features ofpollen grain Most of the pollen grain in the plant kingdom show normal . condition How ever there are many species in which pollen grains remain in a group or as compound pollen grain or may take different association and form for convenience of . pollination These compound pollen are also called as the . pollen aggregates Some major pollen grain abnormalities : are listed below - • Pollinia • Pseudomonads • Massulae • Polyads
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  POLLINI A  Pollinia arecoherent mass of pollen grain often found in Asclepiadaceae, orchidaceae and Apocynaceae etc.  They are the product of only one another but are transferred as a singe unit during pollination .  This abnormality reduces the pollen wastage as this unit or pollinia contain all the pollen grain or microspore which reduces the wastage of pollen after the dehiscence of anther for pollination.  Pollinia remain single as in apocyanaceae or may join in 2 or more to a translator arms structure for pollination and this double unit pollinia other wisely called as pollinarium .  This pollinia contains a sticky disc of tissue which help them to attach to the insect body and this way they help the plant for easy pollination .
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  Pollinia of aAngio spermic plant
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  Common example ofa plant flower showing this feature This is the Calatropis gigantea commonly called as milkweed from the family apocyanaceae show the pollinia condition abnormality
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  PSEUDOMONADS  A typicalfeature of some members of cyperaceae family .  It is a type of pollen in which all the four microspores of the tetrad are enclosed within the wall of a single pollen grain this is because during the tetrad condition due to some reason 3 out of 4 pollen grains get disintegrated or aborted and only one remain functional .  At first it seems to be a loss for the plant pollination and fertilization .  As this decreases the pollen number but this is beneficial to that single functional pollen as it get all sufficient nutrition after the disintegration of the 3 pollen grains .  Pseudomonad are also called as the
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  Pseudomonads Conditions Ina Angio Spermic Pollen
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  Common example ofa plant showing this feature Some members of cyperaceae family plants have this kind of abnormalities .this is the Carex plant commonly called as sedge a member of cyperaceae family which show the Pseudomonads abnormality .
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  Polyads in Pollen: Polyadsare cluster of Pollen grains held together while polyads can be a normal occurrence in some plants, excessive polyads formation could be considered as abnormal and might impact pollen dispersal and fertility. Occur in about 15% of families of flowering plants and in all species of Acacia
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   Massulae arepolyads which contains 8-64 pollens together even at maturity .  They are held together in small units. Massulae are commonly seen in members of mimosaceae .  In the pollinium ,several massulae are present . The shapes of massulae and the number of pollen per massulae vary from one plant species to other when present .  It is a coherent mass of pollen grains (as in certain orchids) developed from a single pollen mother cell, a hardened layer of cytoplasm formed around the maturing microspore . The pollinia MASSULAE
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  Common example ofa plant flower showing this feature This abnormality is seen in the mimosa the member of family Mimosaceae which is commonly called as touch me not plant .
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