The Role of LORELEI in Pollen Tube Reception at the Interface of the Synergid Cell and Pollen Tube Requires the Modified Eight-Cysteine Motif and the Receptor-Like Kinase FERONIA

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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Characterization of the pectin methylesterase inhibitor gene family in Rosaceae and role of PbrPMEI23/39/41 in methylesterified pectin distribution in pear pollen tube

Planta ◽

10.1007/s00425-021-03638-9 ◽

2021 ◽

Vol 253 (6) ◽

Author(s):

Xiaoxuan Zhu ◽

Chao Tang ◽

Qionghou Li ◽

Xin Qiao ◽

Xian Li ◽

...

Keyword(s):

Pollen Tube ◽

Gene Family ◽

Pectin Methylesterase ◽

Pectin Methylesterase Inhibitor ◽

Inhibitor Gene

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Impact of Manganese on Pollen Germination and Tube Growth in Lily

Acta Agrobotanica ◽

10.5586/aa.746 ◽

2021 ◽

Vol 74 ◽

Author(s):

Thomas Sawidis ◽

Gülriz Baycu ◽

Elżbieta Weryszko-Chmielewska ◽

Aneta Sulborska

Keyword(s):

Pollen Tube ◽

Pollen Germination ◽

Surrounding Medium ◽

Pollen Grains ◽

Lilium Longiflorum ◽

Tube Growth ◽

Low Concentrations ◽

Main Effect

Abstract In vitro culture of Lilium longiflorum pollen grains was carried out to determine the role of manganese in pollen germination and pollen tube growth. Pollen germination was adversely affected by the presence of manganese (>10 −8 M), whereas low concentrations (10 −12 –10 −10 M) stimulated the process. Manganese caused morphological anomalies during tube growth, characterized by irregular pollen tube thickening and swollen tips. The main effect was the anomalous cell wall formation at the tip, in which the presence of several organelles reduced the number of secretory vesicles. A loose network of fibrillar material and spherical aggregates, mostly in the tip region, was detected, and this material was progressively loosened into the surrounding medium. As a response to potential toxicity, the excess manganese was isolated in vacuoles, which formed an internal barrier against penetration of manganese to the tip area. Elevated manganese concentrations might affect plant reproduction, resulting in anomalies in gamete development. Consequently, the loss in genetic diversity and decreased fruit set ultimately lower yield.

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