The Mechanism and Key Molecules Involved in Pollen Tube Guidance

Abstract

During sexual reproduction of flowering plants, pollen tube guidance by pistil tissue is critical for the delivery of nonmotile sperm cells to female gametes. Multistep controls of pollen tube guidance can be divided into two phases: preovular guidance and ovular guidance. During preovular guidance, various female molecules, including stimulants for pollen germination and pollen tube growth, are provided to support tube growth toward the ovary, where the ovules are located. After entering the ovary, pollen tubes receive directional cues from their respective target ovules, including attractant peptides for precise, species-preferential attraction. Successful pollen tube guidance in the pistil requires not only nutritional and directional controls but also competency controls to make pollen tubes responsive to guidance cues, regulation to terminate growth once a pollen tube arrives at the target, and strategies to stop ovular attraction depending on the fertilization of female gametes.

NMT1 and NMT3 N-Methyltransferase Activity Is Critical to Lipid Homeostasis, Morphogenesis, and Reproduction

“…The nmt1 nmt3 mutant is a powerful tool for analyzing the physiological functions of including those that appear to preferentially bind to FT (Nakamura et al, 2014 navigation towards the ovule and egg cell (Higashiyama and Takeuchi, 2015). This supports 665 a need for future investigation under a range of conditions as a temperature-conditional male 666 sterility has been reported in an NMT1 silencing line (Mou et al, 2002) and should include 667 examining the possibility that, in the homozygous nmt1 nmt3 double mutant, female 668 sporophytic defects may influence the male gametophyte, such as observed in some female 669 gametophytic mutants (Huck et al, 2003), especially given the strong and specific expression 670 of NMT3 in the synergid area during late ovule development (Fig.…”

Cyclic nucleotide-gated channel 18 is an essential Ca 2+ channel in pollen tube tips for pollen tube guidance to ovules in Arabidopsis

“…CNGC18 | pollen tube guidance | Ca 2+ gradient | Ca 2+ channel | Arabidopsis P ollen tubes deliver paired sperm cells into ovules for double fertilization, and signaling communication between pollen tubes and female reproductive tissues is required to ensure the delivery of sperm cells into the ovules (1). Pollen tube guidance is governed by both female sporophytic and gametophytic tissues (2,3) and can be separated into two categories: preovular guidance and ovular guidance (1).…”

“…Pollen tube guidance is governed by both female sporophytic and gametophytic tissues (2,3) and can be separated into two categories: preovular guidance and ovular guidance (1). For preovular guidance, diverse signaling molecules from female sporophytic tissues have been identified, including the transmitting tissue-specific (TTS) glycoprotein in tobacco (4), γ-amino butyric acid (GABA) in Arabidopsis (5), and chemocyanin and the lipid transfer protein SCA in Lilium longiflorum (6,7).…”

RNA silencing of exocyst genes in the stigma impairs the acceptance of compatible pollen in Arabidopsis

“…In flowering plants, sexual reproduction occurs as a result of constant communication between the male gametophyte and the female reproductive organ, from the initial acceptance of compatible pollen to final step of successful fertilization (for review, see Beale and Johnson, 2013;Dresselhaus and Franklin-Tong, 2013;Higashiyama and Takeuchi, 2015). In the Brassicaceae, the stigmas that present a receptive surface for pollen are categorized as dry and covered with unicellular papillae (Heslop-Harrison and Shivanna, 1977).…”