The role of the integuments in pollen tube guidance in flowering plants

During the evolution of flowering plants, their sperm cells have lost mobility and are transported from the stigma to the female gametophyte via the pollen tube to achieve double fertilization. Pollen tube growth and guidance is largely governed by the maternal sporophytic tissues of the stigma, style and ovule. However, the last phase of the pollen tube path is under female gametophyte control and is expected to require extensive cell–cell communication events between both gametophytes. Until recently, little was known about the molecules produced by the female gametophyte that are involved in this process. In the present paper, we review the most recent development in this field and focus on the role of secreted candidate signalling ligands.

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Pollen tube guidance by the female gametophyte

Development ◽

10.1242/dev.124.12.2489 ◽

1997 ◽

Vol 124 (12) ◽

pp. 2489-2498 ◽

Cited By ~ 1

Author(s):

S.M. Ray ◽

S.S. Park ◽

A. Ray

Keyword(s):

Pollen Tube ◽

Long Range ◽

Female Gametophyte ◽

Chromosomal Translocation ◽

Pollen Grains ◽

Pollen Tubes ◽

Flowering Plants ◽

Genetic Studies ◽

Transmitting Tract ◽

Pollen Tube Guidance

In flowering plants, pollen grains germinate on the pistil and send pollen tubes down the transmitting tract toward ovules. Previous genetic studies suggested that the ovule is responsible for long-range pollen tube guidance during the last phase of a pollen tube's journey to the female gametes. It was not possible, however, to unambiguously identify the signaling cells within an ovule: the haploid female gametophyte or the diploid sporophytic cells. In an effort to distinguish genetically between these two possibilities, we have used a reciprocal chromosomal translocation to generate flowers wherein approximately half the ovules do not contain a functional female gametophyte but all ovules contain genotypically normal sporophytic cells. In these flowers, pollen tubes are guided to the normal but not to the abnormal female gametophytes. These results strongly suggest that the female gametophyte is responsible for pollen tube guidance, but leave open the possibility that the gametophyte may accomplish this indirectly through its influence on some sporophytic cells.

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Spatio-Temporal Distribution of Cell Wall Components in the Placentas, Ovules and Female Gametophytes of Utricularia during Pollination

International Journal of Molecular Sciences ◽

10.3390/ijms22115622 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5622

Author(s):

Bartosz Jan Płachno ◽

Małgorzata Kapusta ◽

Piotr Świątek ◽

Krzysztof Banaś ◽

Vitor F. O. Miranda ◽

...

Keyword(s):

Pollen Tube ◽

Female Gametophyte ◽

Embryo Sac ◽

Temporal Distribution ◽

Arabinogalactan Proteins ◽

Central Cell ◽

Nutritive Tissue ◽

Pollen Tube Guidance ◽

Micropylar Canal

In most angiosperms, the female gametophyte is hidden in the mother tissues and the pollen tube enters the ovule via a micropylar canal. The mother tissues play an essential role in the pollen tube guidance. However, in Utricularia, the female gametophyte surpasses the entire micropylar canal and extends beyond the limit of the integument. The female gametophyte then invades the placenta and a part of the central cell has direct contact with the ovary chamber. To date, information about the role of the placenta and integument in pollen tube guidance in Utricularia, which have extra-ovular female gametophytes, has been lacking. The aim of this study was to evaluate the role of the placenta, central cell and integument in pollen tube pollen tube guidance in Utricularia nelumbifolia Gardner and Utricularia humboldtii R.H. Schomb. by studying the production of arabinogalactan proteins. It was also determined whether the production of the arabinogalactan proteins is dependent on pollination in Utricularia. In both of the examined species, arabinogalactan proteins (AGPs) were observed in the placenta (epidermis and nutritive tissue), ovule (integument, chalaza), and female gametophyte of both pollinated and unpollinated flowers, which means that the production of AGPs is independent of pollination; however, the production of some AGPs was lower after fertilization. There were some differences in the production of AGPs between the examined species. The occurrence of AGPs in the placental epidermis and nutritive tissue suggests that they function as an obturator. The production of some AGPs in the ovular tissues (nucellus, integument) was independent of the presence of a mature embryo sac.

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Interactions between pollen tube and pistil control pollen tube identity and sperm release in the Arabidopsis female gametophyte

Biochemical Society Transactions ◽

10.1042/bst20130223 ◽

2014 ◽

Vol 42 (2) ◽

pp. 340-345 ◽

Cited By ~ 13

Author(s):

Alexander R. Leydon ◽

Adisorn Chaibang ◽

Mark A. Johnson

Keyword(s):

Pollen Tube ◽

Female Gametophyte ◽

Flowering Plants ◽

Flowering Plant ◽

Pollen Tube Guidance ◽

Pollen Cell ◽

Its Gene ◽

Flowering Plant Species ◽

Arabidopsis Pollen ◽

Signalling Systems

Flowering plants have immotile sperm that develop within the pollen cytoplasm and are delivered to female gametes by a pollen tube, a highly polarized extension of the pollen cell. In many flowering plant species, including seed crop plants, hundreds of pollen tubes grow towards a limited number of ovules. This system should ensure maximal fertilization of ovules and seed production; however, we know very little about how signalling between the critical cells is integrated to orchestrate delivery of two functional sperm to each ovule. Recent studies suggest that the pollen tube changes its gene-expression programme in response to growth through pistil tissue and that this differentiation process is critical for pollen tube attraction by the female gametophyte and for release of sperm. Interestingly, these two signalling systems, called pollen tube guidance and pollen tube reception, are also species-preferential. The present review focuses on Arabidopsis pollen tube differentiation within the pistil and addresses the idea that pollen tube differentiation defines pollen tube identity and recognition by female cells. We review recent identification of genes that may control pollen tube–female gametophyte recognition and discuss how these may be involved in blocking interspecific hybridization.

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Pollen Tube Guidance: The Role of Adhesion and Chemotropic Molecules

Current Topics in Developmental Biology ◽

10.1016/s0070-2153(04)61003-9 ◽

2004 ◽

pp. 61-79 ◽

Cited By ~ 14

Author(s):

Sunran Kim ◽

Juan Dong ◽

Elizabeth M. Lord

Keyword(s):

Pollen Tube ◽

Pollen Tube Guidance

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Blazing New Trails (Pollen Tube Guidance in Flowering Plants)

PLANT PHYSIOLOGY ◽

10.1104/pp.113.2.307 ◽

1997 ◽

Vol 113 (2) ◽

pp. 307-312 ◽

Cited By ~ 29

Author(s):

L. K. Wilhelmi ◽

D. Preuss

Keyword(s):

Pollen Tube ◽

Flowering Plants ◽

Pollen Tube Guidance

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Florigen governs shoot regeneration

Scientific Reports ◽

10.1038/s41598-021-93180-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yaarit Kutsher ◽

Michal Fisler ◽

Adi Faigenboim ◽

Moshe Reuveni

Keyword(s):

Nitric Oxide ◽

Shoot Regeneration ◽

Ectopic Expression ◽

Flowering Plants ◽

Regeneration Capacity ◽

No Donor ◽

Tobacco Leaves ◽

Age Related ◽

Delayed Flowering

AbstractIt is widely known that during the reproductive stage (flowering), plants do not root well. Most protocols of shoot regeneration in plants utilize juvenile tissue. Adding these two realities together encouraged us to study the role of florigen in shoot regeneration. Mature tobacco tissue that expresses the endogenous tobacco florigen mRNA regenerates poorly, while juvenile tissue that does not express the florigen regenerates shoots well. Inhibition of Nitric Oxide (NO) synthesis reduced shoot regeneration as well as promoted flowering and increased tobacco florigen level. In contrast, the addition of NO (by way of NO donor) to the tissue increased regeneration, delayed flowering, reduced tobacco florigen mRNA. Ectopic expression of florigen genes in tobacco or tomato decreased regeneration capacity significantly. Overexpression pear PcFT2 gene increased regeneration capacity. During regeneration, florigen mRNA was not changed. We conclude that florigen presence in mature tobacco leaves reduces roots and shoots regeneration and is the possible reason for the age-related decrease in regeneration capacity.

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Paving the Way for Fertilization: The Role of the Transmitting Tract

International Journal of Molecular Sciences ◽

10.3390/ijms22052603 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2603

Author(s):

Ana Marta Pereira ◽

Diana Moreira ◽

Sílvia Coimbra ◽

Simona Masiero

Keyword(s):

Pollen Tube ◽

Pollen Tube Growth ◽

Current Knowledge ◽

Embryo Sac ◽

Tube Growth ◽

Signaling Cascades ◽

Secretory Cells ◽

Transmitting Tract ◽

Specialized Tissue

Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules’ embryo sac, where they fuse with the egg and the central cell to accomplish double fertilization and ultimately initiate seed development. A network of intrinsic and tightly regulated communication and signaling cascades, which mediate continuous interactions between the pollen tube and the sporophytic and gametophytic female tissues, ensures the fast and meticulous growth of pollen tubes along the pistil, until it reaches the ovule embryo sac. Most of the pollen tube growth occurs in a specialized tissue—the transmitting tract—connecting the stigma, the style, and the ovary. This tissue is composed of highly secretory cells responsible for producing an extensive extracellular matrix. This multifaceted matrix is proposed to support and provide nutrition and adhesion for pollen tube growth and guidance. Insights pertaining to the mechanisms that underlie these processes remain sparse due to the difficulty of accessing and manipulating the female sporophytic tissues enclosed in the pistil. Here, we summarize the current knowledge on this key step of reproduction in flowering plants with special emphasis on the female transmitting tract tissue.

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