scholarly journals Rac Homologues and Compartmentalized Phosphatidylinositol 4, 5-Bisphosphate Act in a Common Pathway to Regulate Polar Pollen Tube Growth

1999 ◽  
Vol 145 (2) ◽  
pp. 317-330 ◽  
Author(s):  
Benedikt Kost ◽  
Emmanuel Lemichez ◽  
Pius Spielhofer ◽  
Yan Hong ◽  
Kimberly Tolias ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Intracellular Localization ◽  
Small Gtpases ◽  
Tube Growth ◽  
Yeast Cells ◽  
Common Pathway ◽  
Pollen Tube Elongation ◽  
Rho Family ◽  
Phosphatidylinositol 4

Pollen tube cells elongate based on actin- dependent targeted secretion at the tip. Rho family small GTPases have been implicated in the regulation of related processes in animal and yeast cells. We have functionally characterized Rac type Rho family proteins that are expressed in growing pollen tubes. Expression of dominant negative Rac inhibited pollen tube elongation, whereas expression of constitutive active Rac induced depolarized growth. Pollen tube Rac was found to accumulate at the tip plasma membrane and to physically associate with a phosphatidylinositol monophosphate kinase (PtdIns P-K) activity. Phosphatidylinositol 4, 5-bisphosphate (PtdIns 4, 5-P2), the product of PtdIns P-Ks, showed a similar intracellular localization as Rac. Expression of the pleckstrin homology (PH)-domain of phospholipase C (PLC)-δ1, which binds specifically to PtdIns 4, 5-P2, inhibited pollen tube elongation. These results indicate that Rac and PtdIns 4, 5-P2 act in a common pathway to control polar pollen tube growth and provide direct evidence for a function of PtdIns 4, 5-P2 compartmentalization in the regulation of this process.

scholarly journals Localised and non-localised promotion of fruit development by seeds in Arabidopsis

2006 ◽  
Vol 33 (1) ◽  
pp. 1 ◽  
Author(s):  
Catherine M. Cox ◽  
Stephen M. Swain
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Seed Set ◽  
Fruit Size ◽  
Fruit Growth ◽  
Tube Growth ◽  
Gene Encoding ◽  
Pollen Tube Elongation ◽  
The Relationship ◽  
Silique Length

In Arabidopsis, as in the majority of flowering plants, developing seeds promote fruit growth. One method to investigate this interaction is to use plants with reduced seed set and determine the effect on fruit growth. Plants homozygous for a transgene designed to ectopically express a gene encoding a gibberellin-deactivating enzyme exhibit reduced pollen tube elongation, suggesting that the plant hormone gibberellin is required for this process. Reduced pollen tube growth causes reduced seed set and decreased silique (fruit) size, and this genotype is used to explore the relationship between seed set and fruit elongation. A detailed analysis of seed set in the transgenic line reveals that reduced pollen tube growth decreases the probability of each ovule being fertilised. This effect becomes progressively more severe as the distance between the stigma and the ovule increases, revealing the complex biology underlying seed fertilisation. In terms of seed-promoted fruit growth, major localised and minor non-localised components that contribute to final silique length can be identified. This result demonstrates that despite the relatively small size of the fruit and associated structures, Arabidopsis can be used as a model to investigate fundamental questions in fruit physiology.

Pollen‒pistil interaction in Lilium longiflorum : the role of the pistil in controlling pollen tube growth following cross- and self-pollinations

1982 ◽  
Vol 215 (1198) ◽  
pp. 45-62 ◽  
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Active Component ◽  
Lilium Longiflorum ◽  
The Self ◽  
Tube Growth ◽  
Self Incompatibility ◽  
System A ◽  
Pollen Tube Elongation

By cytophysiological methods, the self-incompatibility mechanism of the breeding system in Lilium longiflorum has been examined with particular reference to the synthesis, location and nature of the stylar factors involved in the control of pollen tube development. A ‘bioassay’ has been developed by which the effect of stylar extracts on pollen tube elongation may be investigated. With use of this system, a crude fraction of proteins from the stylar fluid has been shown to inhibit pollen tube growth only when protein fractions from ‘self’ styles are used. The proteins of this fraction have been analysed by thin-layer gel electrofocusing. Changes in the profiles thus obtained following selfing and a heat treatment known to inactivate the self-incompatibility response indicate a highly polarized glycoprotein to be an active component of the system. The various ways by which such a glycoprotein could control pollen tube elongation are considered in detail, and these events in Lilium are discussed in the light of our knowledge of other self-incompatibility systems operating in angiosperms.

scholarly journals The Arabidopsis thaliana Class II Formin FH13 Modulates Pollen Tube Growth

2021 ◽  
Vol 12 ◽  
Author(s):  
Eva Kollárová ◽  
Anežka Baquero Forero ◽  
Fatima Cvrčková
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Tip Growth ◽  
Pollen Tubes ◽  
Class Ii ◽  
Membrane Dynamics ◽  
Tube Growth ◽  
Class I ◽  
Pollen Tube Elongation

Formins are a large, evolutionarily conserved family of actin-nucleating proteins with additional roles in regulating microfilament, microtubule, and membrane dynamics. Angiosperm formins, expressed in both sporophytic and gametophytic tissues, can be divided into two subfamilies, Class I and Class II, each often exhibiting characteristic domain organization. Gametophytically expressed Class I formins have been documented to mediate plasma membrane-based actin assembly in pollen grains and pollen tubes, contributing to proper pollen germination and pollen tube tip growth, and a rice Class II formin, FH5/RMD, has been proposed to act as a positive regulator of pollen tube growth based on mutant phenotype and overexpression data. Here we report functional characterization of the Arabidopsis thaliana pollen-expressed typical Class II formin FH13 (At5g58160). Consistent with published transcriptome data, live-cell imaging in transgenic plants expressing fluorescent protein-tagged FH13 under the control of the FH13 promoter revealed expression in pollen and pollen tubes with non-homogeneous signal distribution in pollen tube cytoplasm, suggesting that this formin functions in the male gametophyte. Surprisingly, fh13 loss of function mutations do not affect plant fertility but result in stimulation of in vitro pollen tube growth, while tagged FH13 overexpression inhibits pollen tube elongation. Pollen tubes of mutants expressing a fluorescent actin marker exhibited possible minor alterations of actin organization. Our results thus indicate that FH13 controls or limits pollen tube growth, or, more generally, that typical Class II formins should be understood as modulators of pollen tube elongation rather than merely components of the molecular apparatus executing tip growth.

Effect of spermine and cyclohexylamine on in vitro pollen germination and tube growth in Helianthus annuus

2000 ◽  
Vol 80 (2) ◽  
pp. 241-245 ◽  
Author(s):  
Ergü Çetin ◽  
Cansev Yildirim ◽  
Narçin Palavan-Ünsal ◽  
Meral Ünal
Keyword(s):  
Pollen Tube ◽  
Helianthus Annuus ◽  
Pollen Tube Growth ◽  
Pollen Germination ◽  
Germination Percentage ◽  
Tube Growth ◽  
Pollen Tube Elongation ◽  
Relationship Of

Naturally occurring polyamines (PA) are known to play a key role in growth and development of plants and animals. However, the role of these polycations in the development and germination of the pollen grain is not well understood. The effect of different concentrations of spermine (Spm) on pollen tube growth in Helianthus annuus was investigated. Spermine treatments in the 10−7 to 10−5 M range stimulated pollen tube growth starting in the first 15 min of the incubation period, while 10−4 M Spm treatment resulted in inhibition of pollen tube elongation. The effect of cyclohexylamine (CHA), an inhibitor of Spm synthesis on pollen tube growth and germination percentage was also studied. Cyclohexylamine in the 0.5 × 10−3 M to the 1.5 × 10−3 M range inhibited pollen tube elongation. The relationship of B deficiency, excess B and PA effect on pollen germination and pollen tube growth were also investigated. Key words: Polyamines, pollen, cyclohexylamine, boron

scholarly journals Ovary Signals for Pollen Tube Guidance in Chalazogamous Mangifera indica L.

2021 ◽  
Vol 11 ◽  
Author(s):  
Jorge Lora ◽  
Veronica Perez ◽  
Maria Herrero ◽  
Jose I. Hormaza
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Mangifera Indica ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Transmitting Tissue ◽  
Egg Apparatus ◽  
Pollen Tube Elongation

Most flowering plants show porogamy in which the pollen tubes reach the egg apparatus through the micropyle. However, several species show chalazogamy, an unusual pollen tube growth, in which the pollen tubes reach the embryo sac through the chalaza. While ovary signals for pollen tube growth and guidance have been extensively studied in porogamous species, few studies have addressed the process in chalazogamous species such as mango (Mangifera indica L.), one of the five most important fruit crops worldwide in terms of production. In this study, we characterize pollen–pistil interaction in mango, paying special attention to three key players known to be involved in the directional pollen tube growth of porogamous species such as starch, arabinogalactan proteins (AGPs), and γ-aminobutyric acid (GABA). Starch grains were observed in the style and in the ponticulus at anthesis, but their number decreased 1 day after anthesis. AGPs, revealed by JIM8 and JIM13 antibodies, were homogenously observed in the style and ovary, but were more conspicuous in the nucellus around the egg apparatus. GABA, revealed by anti-GABA antibodies, was specifically observed in the transmitting tissue, including the ponticulus. Moreover, GABA was shown to stimulate in vitro mango pollen tube elongation. The results support the heterotrophic growth of mango pollen tubes in the style at the expense of starch, similarly to the observations in porogamous species. However, unlike porogamous species, the micropyle of mango does not show high levels of GABA and starch, although they were observed in the ponticulus and could play a role in supporting the unusual pollen tube growth in chalazogamous species.

Inhibition of Pollen Tube Growth by Diffusate and Extract of Grape Pistils

1989 ◽  
Vol 58 (3) ◽  
pp. 515-521 ◽  
Author(s):  
Goro OKAMOTO ◽  
Ikuo SHIBUYA ◽  
Miwa FURUICHI ◽  
Kazuo SHIMAMURA
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Tube Growth
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