scholarly journals In search of female sterility causes in the tetraploid and pentaploid cytotype of Pilosella brzovecensis (Asteraceae)

2021 ◽  
Author(s):  
Agnieszka Barbara Janas ◽  
Zbigniew Szeląg ◽  
Krystyna Musiał
Keyword(s):  
Embryo Sac ◽  
Endosperm Development ◽  
Female Sterility ◽  
Early Prophase ◽  
Growing Seasons ◽  
Ovule Sterility ◽  
Viable Seeds ◽  
Reproductive Events ◽  
Embryological Analysis ◽  
Reproductive Processes

AbstractWithin the agamic Pilosella complex, apomixis (asexual reproduction through seed) involves apospory, parthenogenesis, and autonomous endosperm development. Observations of reproductive biology in P. brzovecensis throughout four growing seasons in the garden have shown that both tetraploid and pentaploid plants of this species do not produce viable seeds and reproduce exclusively vegetatively by underground stolons. The reasons for the seed development failure were unknown, therefore our research focused on the analysis of reproductive events in the ovules of this taxon. We found that apospory was initiated in the ovules of both cytotypes. Multiple aposporous initial (AI) cells differentiated in close proximity to the megaspore mother cell (MMC) and suppressed megasporogenesis at the stage of early prophase I. However, none of the AI cells was able to further develop into a multi-nucleate aposporous embryo sac (AES) due to the inhibition of mitotic divisions. It was unusual that callose was accumulated in the walls of AI cells and its synthesis was most likely associated with a response to the dysfunction of these cells. Callose is regarded as the isolating factor and its surprising deposition in the ovules of P. brzovecensis may signal disruption of reproductive processes that cause premature termination of the aposporous development pathway and ultimately lead to ovule sterility. The results of our embryological analysis may be the basis for undertaking advanced molecular studies aimed at fully understanding of the causes of female sterility in P. brzovecensis.

scholarly journals Grain yield and competitive ability against weeds in modern and heritage common wheat cultivars are differently influenced by sowing density

2017 ◽  
Vol 11 ◽  
Author(s):  
Mariateresa Lazzaro ◽  
Ambrogio Costanzo ◽  
Dalia Hosam Farag ◽  
Paolo Bàrberi
Keyword(s):  
Grain Yield ◽  
Common Wheat ◽  
Weed Suppression ◽  
Strong Impact ◽  
Wheat Cultivars ◽  
Modern Cultivar ◽  
Weed Biomass ◽  
Growing Seasons ◽  
Viable Seeds ◽  
Crop Stand

Sowing density can have a strong impact on crop stand development during wheat growing cycle. In organic and low-input agriculture, and therefore with minimum or nil use of chemical herbicides, increased sowing density is expected to affect not only grain yield but also weed suppression. In this study we tested, under Mediterranean conditions, six common wheat cultivars (three modern and three heritage) and two three-component mixtures (arranged by combining the three modern or the three heritage cultivars). The different crop stands were tested at sowing densities of 250 (low) and 400 (high, similar to standard sowing density used by local farmers) viable seeds m-2 for two growing seasons. We did not detect a significant effect of crop stand diversity (single cultivars vs mixtures) on grain yield and weed suppression. Differences were ascribed to type of cultivars used (heritage vs modern). Compared to high sowing density, in modern cultivars grain yield did not decrease significantly with low sowing density whereas in heritage cultivars it increased by 15.6%, possibly also because of 21.5% lower plant lodging. Weed biomass increased with low sowing density both in heritage and modern cultivar crop stand types. However, heritage crop stands had, on average, a lower weed biomass (56%) than modern crop stands. Moreover, weed biomass in heritage crop stands at low density (6.82 ± 1.50 g m-2) was lower than that of modern cultivars at the same sowing density (15.54 ± 3.35 g m-2), confirming the higher suppressive potential of the former. We can conclude that lower sowing density can be advisable when using heritage crop stands as it keeps productivity while decreasing plant lodging and maintaining weeds under control.

Embryology of Isotoma petraea

1970 ◽  
Vol 18 (2) ◽  
pp. 213 ◽  
Author(s):  
IC Beltran
Keyword(s):  
Mother Cell ◽  
Embryo Sac ◽  
Endosperm Development ◽  
Ovule Development ◽  
Polygonum Type ◽  
Development Patterns ◽  
Embryo Formation ◽  
Ring Bivalents ◽  
Form Ring ◽  
Embryo Sac Formation

Ovule development, embryo sac formation, and embryogeny of I. Petraea are described. The ovules are anatropous, unitegmic, and tenuinucellar. Meiosis in the megaspore mother cell is regular and the chromosomes with terminalized chiasmata form ring bivalents at metaphase 1. The Polygonum type embryo sac, Scutellaria type endosperm development, and Solanad embryo formation correspond with development patterns in other members of the Lobeliaceae.

scholarly journals Ovules, Female Gametophytes and Embryos are More Sensitive to Heavy Metal Pollution than Anthers and Pollen of Cardaminopsis Arenosa (L.) Hayek (Brassicaceae), A Member of Calamine Flora

2014 ◽  
Vol 56 (1) ◽  
pp. 128-137 ◽  
Author(s):  
Kwiatkowska Monika ◽  
Izmaiłow Romana
Keyword(s):  
Low Frequency ◽  
Endosperm Development ◽  
Male Meiosis ◽  
Plant Tolerance ◽  
Developmental Disturbances ◽  
Polluted Sites ◽  
Reproductive Processes ◽  
Very High ◽  
S Poland ◽  
Plant Fertility

Abstract Reproductive processes including male and female lines, embryo and endosperm development were studied in Cardaminopsis arenosa (syn. Arabidopsis arenosa) growing on two metalliferous sites (Bukowno and Bolesław, S. Poland), rich in Zn, Pb, Cd and other metals. Disturbances of developmental processes and necroses observed in anthers and ovules influenced plant fertility and seed set of plants from both metal-polluted sites. In anthers, disturbances and necrosis during male meiosis and pollen development occurred at low frequency (4-5%). Pollen grain viability was very high, reaching over 90%. In ovules the frequency of abnormal meiosis, female gametophyte developmental disturbances and necrosis was high, 23.5-28% depending on site. The polluted environment also affected embryo and endosperm. Necrosis of whole generative structures decreased plant fertility. This study indicates that the range of disturbances and necroses in embryological structures and processes (at gametophyte level) gives a set of useful characters to determine plant tolerance to stress, complementary to many tolerance characters at the sporophyte level of plant ontogenesis.

Female gametophyte and seed development in Musella lasiocarpa (Musaceae), a monotypic genus endemic to Southwestern China

2007 ◽  
Vol 85 (10) ◽  
pp. 964-975 ◽  
Author(s):  
Chun-Ying Xue ◽  
Hong Wang ◽  
De-Zhu Li
Keyword(s):  
Seed Development ◽  
Female Gametophyte ◽  
Wild Population ◽  
Embryo Sac ◽  
Single Species ◽  
Ex Situ ◽  
Southwestern China ◽  
Conservation Strategies ◽  
Female Sterility ◽  
Monotypic Genus

Musella is a monotypic genus composed of a single species, Musella lasiocarpa (Franch.) C.Y. Wu ex H.W. Li, endemic to Southwestern China. The genus status of Musella remains controversial. Musella had been placed first in Musa , then in Ensete , and back to Musa before its monotypic status was recognized. Musella was reported to be extinct in the wild and maintained through cultivation only via vegetative propagation through sprouting of rhizomes. In this study, female gametophyte and seed development of Musella are described to assess its systematic position and possible reasons why the wild population is now extinct. The ovules are anatropous, bitegmic, and crassinucellar. The micropyle is formed by both integuments. The megaspore mother cell undergoes meiotic division and forms a linear megaspore triad or more rarely, a T-shaped megaspore tetrad. The chalazal megaspore develops into a Polygonum type embryo sac. A nucellar pad forms, and a hypostase differentiates. Fertilization is porogamous. Endosperm formation is of the nuclear type. The zygote degenerates and so the process by which the embryo develops, if it does, remains unclear. An operculum, micropylar collar, and chalazal chamber form in mature seeds. The storage tissue is mainly endosperm containing large, compound starch grains and some perisperm. The seed coat has lignified exotestal cells, 25–30 cell layers of sclerotic mesotestal cells, and unspecialized endotesta cells; the tegment consists of two layers of longitudinally elongated cells. The seed is inviable. After comparison with the other Musaceae s. str. taxa using embryological and botanical features, we conclude that Musella should be a distinct genus. Female sterility in Musella may be the main reason why the wild population is extinct. Based on these findings, we propose conservation strategies for this endemic species, including habitat protection as well as ex-situ conservation.

The development of the embryo sac of sunflower Helianthus annuus after fertilization

1973 ◽  
Vol 51 (5) ◽  
pp. 879-890 ◽  
Author(s):  
William Newcomb
Keyword(s):  
Helianthus Annuus ◽  
Mitotic Spindle ◽  
Embryo Sac ◽  
Endosperm Development ◽  
Primary Endosperm Nucleus ◽  
Single Row ◽  
Wall Formation ◽  
Globular Stage ◽  
Spindle Apparatus ◽  
Single Fertilization

The degeneration of one synergid denotes the initiation of embryo and endosperm development in the embryo sac of sunflower Helianthus annuus L. The other synergid, the persistent synergid, is present until the late globular stage of embryogenesis. The primary endosperm nucleus divides before the zygote nucleus forming a coenocytic nuclear endosperm. When about eight endosperm nuclei are present during the early globular stage of embryogenesis, endosperm wall formation starts at the micropylar end of the embryo sac. The walls continue to grow toward the chalazal end of the embryo sac apparently as a result of the activity of Golgi located at the tips of the growing walls. Most endosperm wall formation is not associated with a mitotic spindle apparatus in sunflower. The suspensor of the embryo consists of a large basal cell during the proembryo stages, a single row of cells during the early globular stages, and at the late globular stage a double tier of cells near the radicle end of the embryo and a single row at the micropylar end of the embryo sac. Occasionally embryo development occurs in the absence of endosperm when only single fertilization has taken place. The development and nutritional implications of post-fertilization events in the sunflower embryo sac are discussed.

Ovule, embryo sac, embryo, and endosperm development in leafy spurge (Euphorbia esula)

1999 ◽  
Vol 77 (4) ◽  
pp. 599-610 ◽  
Author(s):  
Jeffrey S Carmichael ◽  
Sarena M Selbo
Keyword(s):  
Embryo Sac ◽  
Placental Tissue ◽  
Leafy Spurge ◽  
Endosperm Development ◽  
Protein Bodies ◽  
Euphorbia Esula ◽  
Invasive Weed ◽  
Polygonum Type ◽  
Nutrient Reserve ◽  
Endosperm Formation

Leafy spurge (Euphorbia esula L.) is a noxious, invasive weed that dominates many agriculturally important regions. While many research efforts are currently aimed at controlling the spread of this plant, relatively little is known about its sexual reproductive biology, especially from a structural perspective. This report describes key features of ovule development, embryogenesis, and endosperm formation in leafy spurge. Ovules are anatropous, bitegmic, and form a zigzag micropyle. A distinct elaisome (caruncle) and hypostase are formed as ovules mature. Obturators are present and are derived from placental tissue. The embryo sac conforms to the Polygonum type. A single embryo is formed in each seed and stores nutrients primarily as globoid protein bodies. Endosperm is persistent and also contains protein bodies as its primary nutrient reserve. Preliminary structural evidence is presented that indicates the potential for apomixis.Key words: leafy spurge, Euphorbiaceae, Euphorbia, ovule, endosperm, embryo.

scholarly journals Embriología de Erythroxylum havanense Jacq. (Erythroxylaceae)

2017 ◽  
pp. 25
Author(s):  
Sonia Vázquez-Santana ◽  
César A. Domínguez ◽  
Judith Márquez-Guzmán
Keyword(s):  
Seed Coat ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Endosperm Development ◽  
Anther Wall ◽  
Starch Grains ◽  
Reproductive Structures ◽  
Exine Sculpturing ◽  
Erythroxylum Havanense ◽  
Mature Anther

We studied the development of reproductive structures in pin and thrum morphs of Erythroxylum havanense. The young anther wall consists of an epidermis, endothecium , 1-3 middle layers anda binucleate secretory tapetum. The mature anther wall has only two layers: epidermis and endothecium. Microspore tetrads are tetrahedral or isobilateral. Mature pollen grains are tricolporate, bicellular and contain starch grains. Exine sculpturing is verrugate in thrum pollen and reticulate in pin pollen. The ovule is sessile, pendulous, anatropous, bitegmic and crassinucellate. The embryo sac is heptacellular. An endothelium is differentiated. The endosperm development is nuclear, and the basal part of the nucellus persists during early endosperm development. Both integuments form the seed coat.

Nucleolus-associated telomere clustering and pairing precede meiotic chromosome synapsis in Arabidopsis thaliana

2001 ◽  
Vol 114 (23) ◽  
pp. 4207-4217 ◽  
Author(s):  
Susan J. Armstrong ◽  
F. Christopher H. Franklin ◽  
Gareth H. Jones
Keyword(s):  
Arabidopsis Thaliana ◽  
Meiotic Chromosome ◽  
In Situ Hybridisation ◽  
Embryo Sac ◽  
Early Prophase ◽  
Homologous Chromosomes ◽  
Chromosome Synapsis ◽  
Mother Cells ◽  
Telomere Signal

The intranuclear arrangements of centromeres and telomeres during meiotic interphase and early prophase I of meiosis in Arabidopsis thaliana were analysed by fluorescent in situ hybridisation to spread pollen mother cells and embryo-sac mother cells. Meiocyte identification, staging and progression were established by spreading and sectioning techniques, including various staining procedures and bromodeoxyuridine labeling of replicating DNA. Centromere regions of Arabidopsis are unpaired, widely dispersed and peripherally located in nuclei during meiotic interphase, and they remain unpaired and unassociated throughout leptotene. Eventually they associate pairwise during zygotene, as part of the nucleus-wide synapsis of homologous chromosomes. Telomeres, by contrast, show a persistent association with the nucleolus throughout meiotic interphase. Variation in telomere signal number indicates that telomeres undergo pairing during this interval, preceding the onset of general chromosome synapsis. During leptotene the paired telomeres lose their association with the nucleolus and become widely dispersed. As the chromosomes synapse during zygotene, the telomeres reveal a loose clustering within one hemisphere, which may represent a degenerate or relic bouquet configuration. We propose that in Arabidopsis the classical leptotene/zygotene bouquet is absent and is replaced functionally by nucleolus-associated telomere clustering.

scholarly journals Meiotic behavior of interspecific hybrids between artificially tetraploidized sexual Brachiaria ruziziensis and tetraploid apomictic B. brizantha (Poaceae)

2010 ◽  
Vol 67 (2) ◽  
pp. 191-197 ◽  
Author(s):  
Mariana Ferrari Felismino ◽  
Maria Suely Pagliarini ◽  
Cacilda Borges do Valle
Keyword(s):  
Nutritive Value ◽  
Production Systems ◽  
Genetic Recombination ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Endosperm Development ◽  
Breeding Program ◽  
Meiotic Behavior ◽  
Brachiaria Ruziziensis ◽  
Sexual Hybrid

The meiotic behavior of four interspecific promising hybrids was evaluated by conventional cytological methods. The female genitors were two artificially tetraploidized sexual accessions of B. ruziziensis (R41 and R44, 2n = 4χ = 36), which were crossed to an agronomically superior natural tetraploid apomictic genotype of B. brizantha (B140 - BRA003395). Three of them (HBGC313, HBGC 315, and HBGC324) were sexual and one (HBGC325) apomictic. Analyses of some cells in diakinesis revealed multivalent chromosome configurations, suggesting that genetic recombination and introgression of some genes could be present. The four hybrids had different types of meiotic abnormalities at various frequencies. Abnormalities related to irregular chromosome segregation due to polyploidy were common among these hybrids, and characterized by precocious chromosome migration to the poles, laggard chromosomes, both generating micronuclei in telophases and tetrads and, as a consequence, unbalanced gametes. One abnormality genotype-specific, related to spindle orientation (a putative divergent spindle mutation), was recorded for the first time in two of the hybrids, HBGC313 and HBGC325. The sexual hybrid HBGC324 had the lower rate of abnormalities, and it could be used as a female genitor in future crosses in the breeding program. The abnormalities present in these hybrids may impact fertility and affect seed production. Based on the results, HBGC324 is the single hybrid recommended to the breeding program. Hybrids must produce a good amount of viable seeds, besides good overall dry matter production and nutritive value, in order to be widely utilized and adopted in production systems. Due to pseudogamy, the desirable superior apomictic hybrids need viable pollen grains to fertilize the secondary nucleus of the embryo sac and thus ensure normal and vigorous endosperm development and plenty of seed set.

The acceleration of jack pine seed development

1987 ◽  
Vol 17 (11) ◽  
pp. 1408-1415 ◽  
Author(s):  
Robert A. Cecich ◽  
Edmund O. Bauer
Keyword(s):  
Reproductive Cycle ◽  
Shoot Elongation ◽  
Growth Conditions ◽  
Jack Pine ◽  
Growing Seasons ◽  
Natural Photoperiod ◽  
Germination Success ◽  
Accelerated Growth ◽  
Terminal Shoot ◽  
Viable Seeds

The time from emergence of an ovulate strobilus to collection of viable seeds can be reduced to as little as 9 months instead of the usual 16 months spread over two growing seasons. The procedure is called the "shortened reproductive cycle." Two-year-old jack pine (Pinusbanksiana Lamb.) seedlings, grown under accelerated growth conditions, were brought into a greenhouse in the fall, where the environment simulated natural photoperiod and temperature conditions encountered during a growing season, including the approach of fall and winter. Ovulate strobili that subsequently emerged were pollinated and "2nd-year" cones, derived from those strobili, were collected the following September. The yield of filled seeds per cone was low and germination success was variable. The seedlings derived from the shortened reproductive cycle appeared to be normal and produced their own ovulate strobili 14 months after germination. Exposure to the greenhouse environment stimulated pollen production but decreased production of ovulate strobili 1 year after transplanting to the nursery. Flowering during the shortened reproductive cycle procedure was further promoted with gibberellin A4/7 application at the end of terminal shoot elongation in the greenhouse during the winter. Ovulate strobili were observed 6 months later in the nursery.

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