Flora’s Secret Gardens

2018 ◽  
Author(s):  
Lincoln Taiz ◽  
Lee Taiz
Keyword(s):  
Pollen Tube ◽  
Embryo Sac ◽  
Flowering Plants ◽  
Sexual Stage ◽  
Male And Female ◽  
Plant Kingdom ◽  
Asexual Spore ◽  
The Rose ◽  
Plant Sex ◽  
Alternation Of Generations

Wilhelm Hofmeister established the unity of the Plant Kingdom through the discovery of Alternation of Generations. In both cryptogams and flowering plants a diploid asexual stage, or sporophyte, alternates with a haploid sexual stage. Thus the flower is not the true sexual stage, but rather the asexual spore-producing stage. The main difference between ferns and roses is that the spores of the fern are visible on the undersides of the leaves, while the spores of the rose are concealed within the anthers and ovaries. These spores develop into the actual sexual stage of the spermatophyte, the male and female gametophytes, i.e. the pollen tube and the embryo sac. Hofmeister’s discovery solved of the age-old quandary over plant sex. The sexualists and the asexualists can both claim to have been correct, but it was the sexualists who freed their minds from cultural biases and glimpsed the true sexual nature of plants.

scholarly journals Male and female synchrony and the regulation of mating in flowering plants

2003 ◽  
Vol 358 (1434) ◽  
pp. 1019-1024 ◽  
Author(s):  
M. Herrero
Keyword(s):  
Pollen Tube ◽  
Flowering Plants ◽  
Developmental Pathways ◽  
Control Points ◽  
Male And Female ◽  
Successful Mating ◽  
Synchronous Development ◽  
Developmental Programme

Successful mating clearly requires synchronous development of the male and female sexual organs. Evidence is accumulating that this synchrony of development also persists after pollination, with both pollen and pistil following complex, but highly integrated developmental pathways. The timing of the male–female interaction is crucial for the pistil, which, far from being a mature passive structure, is engaged in a continuing programme of development: only being receptive to the advances of the pollen for a relatively short window of time. This developmental programme is most conspicuous in the ovary, and this review focuses on the interaction between the male and female tissues in this structure. The review first considers pollen tube development in the ovary, concentrating of the mechanisms by which its growth is modulated at various control points associated with structures within the ovary. Second, alterations to this ‘normal’ developmental programme are reviewed and considered in the context of a breakdown of developmental synchrony. Finally, the consequences of male–female developmental synchrony and asynchrony are explored. Clearly, a synchronous male–female relationship leads to a successful fertilization. However, lack of synchrony also occurs, and could emerge as a powerful tool to investigate the regulation of mating.

Calcium Distribution and Accumulation in Ovules of Plumbago Zeylanica

2000 ◽  
Vol 6 (S2) ◽  
pp. 696-697
Author(s):  
Hua Zhu ◽  
Scott D. Russell
Keyword(s):  
Pollen Tube ◽  
Apoptotic Cell ◽  
Embryo Sac ◽  
Flowering Plants ◽  
Cell Type ◽  
Mobile Form ◽  
Plumbago Zeylanica ◽  
Male Gametes ◽  
High Concentrations ◽  
Potassium Pyroantimonate

The embryo sac (ES) of Plumbago zeylanica, unlike most other flowering plants, lacks synergidsthe cell type that usually receives the pollen tube and the male gametes. Normally, synergids store copious amounts of calcium, estimated to exceed 15% by weight; this is believed to attract pollen tubes, which penetrate the ES, and may trigger the release of the sperm cells within one of the two synergids. If high concentrations of calcium are truly required for fertilization, the ES of Plumbago should also contain significant quantities. Synergids in normal flowering plants are preprogrammed for cell death, receiving the contents of the pollen tube directly in their cells, whereas synergid-lacking angiosperms apparently do not have such an apoptotic cell in the ES. Potassium pyroantimonate labeling was used to localize principally loosely-bound calcium, because it is a relatively mobile form of the Ca2+ ion that is available for redistribution during fertilization events.

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

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.

scholarly journals The mac1 Gene: Controlling the Commitment to the Meiotic Pathway in Maize

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 1009-1020 ◽  
Author(s):  
William F Sheridan ◽  
Nadezhda A Avalkina ◽  
Ivan I Shamrov ◽  
Tatyana B Batyea ◽  
Inna N Golubovskaya
Keyword(s):  
Female Gametophyte ◽  
Embryo Sac ◽  
Flowering Plants ◽  
Normal Female ◽  
Ovule Development ◽  
Partial Sterility ◽  
Embryo Sac Formation ◽  
Female Gametophyte Development ◽  
Normal Meiosis ◽  
Pleiotropic Mutation

Abstract The switch from the vegetative to the reproductive pathway of development in flowering plants requires the commitment of the subepidermal cells of the ovules and anthers to enter the meiotic pathway. These cells, the hypodermal cells, either directly or indirectly form the archesporial cells that, in turn, differentiate into the megasporocytes and microsporocytes. We have isolated a recessive pleiotropic mutation that we have termed multiple archesporial cells1 (macl) and located it to the short arm of chromosome 10. Its cytological phenotype suggests that this locus plays an important role in the switch of the hypodermal cells from the vegetative to the meiotic (sporogenous) pathway in maize ovules. During normal ovule development in maize, only a single hypodermal cell develops into an archesporial cell and this differentiates into the single megasporocyte. In macl mutant ovules several hypodermal cells develop into archesporial cells, and the resulting megasporocytes undergo a normal meiosis. More than one megaspore survives in the tetrad and more than one embryo sac is formed in each ovule. Ears on mutant plants show partial sterility resulting from abnormalities in megaspore differentiation and embryo sac formation. The sporophytic expression of this gene is therefore also important for normal female gametophyte development.

Overgrowth of Pollen Tubes in Embryo Sacs of Rhododendron Following Interspecific Pollinations

1986 ◽  
Vol 34 (4) ◽  
pp. 413 ◽  
Author(s):  
EG Williams ◽  
V Kaul ◽  
JL Rouse ◽  
BF Palser
Keyword(s):  
Pollen Tube ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Egg Cell ◽  
Interspecific Crosses ◽  
Main Body

Frequent overgrowths of pollen tubes within the embryo sac are characteristic of a number of interspecific crosses in the genus Rhododendron (Ericaceae). The combined techniques of sectioning, squashing and whole-ovule clearing have confirmed that in ovules showing this phenomenon the pollen tube fails to terminate growth and release sperms on entry into a synergid; instead it continues to grow beyond the synergid and egg cell, often filling the main body of the embryo sac with a coiled and distorted mass. Such ovules fail to develop further. The occurrence and possible causes of this error syndrome are discussed.

A rapid method for sex identification in Cannabis sativa using High Resolution Melt (HRM) analysis.

Botany ◽  
2021 ◽  
Author(s):  
Erin Jacqueline Gilchrist ◽  
Daniela Hegebarth ◽  
Shumin Wang ◽  
Teagen D. Quilichini ◽  
Jason Sawler ◽  
...  
Keyword(s):  
High Resolution ◽  
Rapid Method ◽  
X Chromosome ◽  
Cannabis Sativa ◽  
Sex Identification ◽  
Male Plant ◽  
High Resolution Melt ◽  
Male And Female ◽  
High Resolution Melt Analysis ◽  
Plant Sex

We report the identification of two SNPs in Cannabis sativa that are associated with female and male plant sex phenotypes, and are located on the top arm of the X chromosome. High Resolution Melt analysis was used to develop and validate a novel, rapid method for sex identification in medical/recreational cannabis as well as in hemp. This method can distinguish between dioecious male (XY) and dioecious female (XX) cannabis plants with 100% accuracy, and can also be used to differentiate between male and female Humulus lupulus (hop) plants.

Ultrastructural Aspects of the Self-Incompatibility Mechanism in Lycopersicum Peruvianum Mill

1973 ◽  
Vol 12 (2) ◽  
pp. 403-419 ◽  
Author(s):  
D. DE NETTANCOURT ◽  
M. DEVREUX ◽  
A. BOZZINI ◽  
M. CRESTI ◽  
E. PACINI ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Tube Wall ◽  
Degradation Mechanism ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Self Incompatibility ◽  
Weak Reaction ◽  
General Hypothesis ◽  
Incompatible Pollen ◽  
Compatible Pollen

The experimental results obtained show that the tip of the incompatible pollen tube bursts open after the outer-wall has considerably expanded in the intercellular spaces of the conducting tissue and the inner-wall has disappeared and numerous particles have accumulated in the tube cytoplasm. These particles, which measure approximately 0.2 µm in diameter and give a weak reaction to the test of Thiéry, differ in many respects from the vesicles normally present in compatible pollen tubes growing through the style; they appear to resemble, in some cases, the spheres which are discharged by the compatible pollen tubes after they have reached the embryo-sac. It is considered that these observations support the current belief that the tube wall is the site of action for the incompatibility proteins and suggest that self-incompatibility is not a passive process resulting from lack of growth stimulation but an active event which leads to the destruction of the incompatible pollen tubes. The degradation mechanism involved appears similar to the one which enables the compatible pollen tube to release its contents in the degenerated synergid and presents some analogies with the lytic process taking place in virus-infected cells. The general hypothesis is presented that the particles observed in the cytoplasm of self-incompatible pollen tubes consist of a mixture of incompatibility proteins and of basic constituents of the tube wall.

scholarly journals Arabinogalactan proteins (AGPs) related to pollen tube guidance into the embryo sac in Arabidopsis

2008 ◽  
Vol 3 (7) ◽  
pp. 455-456 ◽  
Author(s):  
Sílvia Coimbra ◽  
Brian Jones ◽  
Luís Gustavo Pereira
Keyword(s):  
Pollen Tube ◽  
Embryo Sac ◽  
Arabinogalactan Proteins ◽  
Pollen Tube Guidance
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