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The Processes Of?Pollination And Double Fertilization In?Arabidopsis

1 Pollination

Pollination in angiosperms is the process of transferring pollen grains from the anther of the stamen, the male organ of the flower, to the stigma of the pistil, the female organ of the flower.

Arabidopsis thaliana (L.) Heynh.is?Angiospermae?phyla,Dicotyledoneae, Cruciferae.Annual herbs,Usually self-pollinated, flowering pollinated, in rare cases rely on insect or wind cross-pollinated.

2 Fertilization

Fertilization?in Arabidopsis is the process of?both sexual gametes fuse with each other within the flowers,this process has been divided into three?phases.

2.1 Pollen grain germinates

???After pollen grain landing on the stigma, lipids and proteins from the pollen coat flow out onto the stigma and mingle with materials from papillar cells to form the “foot,” a structure that attaches the pollen grain firmly to the tip of the papillar cell. During this process, the lipids in the foot are thought to reorganize, creating a capillary system through which water and ions can flow from the stigma to the pollen grain.After hydration, the volume and metabolism of the pollen grain increases, the internal material of the vegetative cells increases, and the intracellular pressure increases, forcing the intine?wall?of the pollen grain to highlight toward the germ pore, forming a pollen tube.

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2.2 Pollen tubes grow

??Following germination, the pollen tube begins to grow though the nutrient-rich extracellular matrix of the transmitting tissue that connects the stigma, style, and ovary.Then,the pollen tube reaches the embryo sac through the micropyle after crossing the septum to the ovary.Finally, Pollen tube penetrates the egg sac, and enters one of the synergid cells through the filiform apparatus. Pollen tube ceases to grow, and the tip bursts to release the two sperm cells.

2.3 Fertilization

??The fertilization can be divided into three stages in Arabidopsis.?First, the pollen tube bursts within a few seconds of entering the synergid,the sperm and contents were injected into the embryo sac. Second, the two sperm cells remain stationary at a boundary region between the egg cell and the central cell for approximately 7 min. Third, one sperm fuse with egg cells to form a zygote,it will develop into embryos in the future.the other fuses with the central cell to form primary endosperm cell,it will develop into endosperm in the future,completing double fertilization.

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Reference：

[1]?譚永耀,擬南芥自然居群的傳粉機制與交配系統(tǒng),【D】,武漢大學(xué),2004,undefined

[2]?Lincoln Taiz, Eduardo Zeiger, Ian M. M?ller, and Angus Murphy Plant Physiology and Development, Sixth Edition [M] published by Sinauer Associates.2015

[3]?馬煒良主編，馬煒良、王幼芳、李宏慶 編著.?植物學(xué) 第2版[M]. 北京：高等教育出版社, 2015.08