Vegetative and reproductive development of shoot apices of Pharbitis nil as influenced by photoperiodism

1969 ◽  
Vol 47 (9) ◽  
pp. 1403-1406 ◽  
Author(s):  
D. S. Bhar ◽  
N. W. Radforth
Keyword(s):  
Mitotic Activity ◽  
Dark Period ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Epidermal Cells ◽  
Floral Transition ◽  
Pharbitis Nil ◽  
Shoot Apices ◽  
The Third

In shoot apices of Pharbitis nil, cytohistological zonation is not clearly delineated at germination. With increase in age, zonation develops and the granular appearance of the cytoplasm disappears. After induction by a single 16-hour dark period the first recognizable sign of floral transition becomes evident on the second day, with increase in the mitotic activity of the apex. On the third and fourth days, the sepals are initiated and the petals and stamens are initiated simultaneously on the fifth day. On the sixth day the carpel primordia originate. Between the 11th and 12th days after the inductive dark period, the pollen grains develop and the style extends. Between the 19th and 20th days the epidermal cells of the stigma become secretory.

scholarly journals The effect of photoperiodic treatments on mitotic activity in Pharbitic nil Chois

10.5586/1201 ◽  
2014 ◽  
Vol 60 (1-2) ◽  
pp. 133-138
Author(s):  
Joanna Czaplewska ◽  
Jan Kopcewicz
Keyword(s):  
Mitotic Activity ◽  
Mitotic Index ◽  
Dark Period ◽  
Continuous Light ◽  
The State ◽  
Pharbitis Nil ◽  
Shoot Apices ◽  
Inductive Cycle ◽  
Short Day ◽  
Inductive Photoperiod

The short-day plant, <i>Pharbitis nil</i>, requires only a single inductive cycle with a 16-hour dark period for flowering. The mitotic activity in the shoot apices was studied directly after the termination of the inductive photoperiod. A pronounced rise in the mitotic index was found in the 2nd and the 8th-14th hours. Control plants grown under noninductive conditions (continuous light, a light interruption in the middle of the dark period) did not flower and did not show an increased mitotic index. The increased mitotic activity in the shoot apices of <i>Pharbitis</i> seems to be causally connected with the phytochrome-controlled entry of the plants into the state of generative induction.

scholarly journals Structure of the floral parts of Crocus vernus (L.) Hill.

2012 ◽  
Vol 64 (4) ◽  
pp. 35-46 ◽  
Author(s):  
Elżbieta Weryszko-Chmielewska ◽  
Mirosława Chwil
Keyword(s):  
Glandular Trichomes ◽  
Pollen Grains ◽  
Climatic Conditions ◽  
Epidermal Cells ◽  
The Third ◽  
Flower Stem ◽  
Significant Length ◽  
Perianth Tube ◽  
Narrow Space ◽  
Parenchymal Cells

In the climatic conditions of Lublin, <i>Crocus vernus</i> blooms from the third decade of March until the third decade of April. The flowers live for 3-4 days. Micromorphological investigations of the tepals and perianth tube as well as of the stamens and pistil were carried out using scanning electron microscopy. The anatomical features of the perianth segments and flower stem were examined with the use of light and fluorescence microscopy. Pollen grains were observed under a light microscope. It was found that the adaxial and abaxial epidermal cells formed papillae in the middle and lower part of the tepals. Much smaller papillae are formed in the upper region of the perianth tube. Elongated non-glandular and glandular trichomes, with spherical protrusions at the tip, are found at the base of the filaments. The filaments are distinguished by epidermal cells with a longitudinally striated cuticle and by the presence of papillae of varying number and size. The cylindrical papillae on the stigma of the pistil are covered by a wrinkled cuticle. The style is surrounded by the perianth tube along a significant length. A narrow space is formed between these organs, and it is filled by the nectar. Stylar channels are found in the style. We observed calcium oxalate crystals and numerous plastids in the parenchymal cells surrounding these channels. Inaperturate, spherical pollen grains are covered by numerous tryphine (or pollenkitt) droplets. This paper also discusses the functions of the papillae found in the epidermis of the perianth and filaments.

In vitro studies of floral shoot apices of Pharbitis nil

1970 ◽  
Vol 48 (7) ◽  
pp. 1355-1358 ◽  
Author(s):  
D. S. Bhar
Keyword(s):  
Dark Period ◽  
Floral Organ ◽  
In Vitro Studies ◽  
Pharbitis Nil ◽  
Shoot Apices ◽  
Intact Plants ◽  
Full Complement

Shoot apices of Pharbitis nil were excised and cultured in vitro at different intervals after the intact plants were photoperiodically induced. The induced apices excised immediately after and up to 24 h after an inductive dark period, grew vegetatively for at least 4 weeks in culture. The apices excised and cultured from intact plants at 36 and 48 h after induction initiated a full complement of floral-organ primordia when observed after 4 weeks of growth.

Reproductive development in two species of Darwinia Rudge (Myrtaceae)

1969 ◽  
Vol 17 (2) ◽  
pp. 215 ◽  
Author(s):  
N Prakash
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Outer Zone ◽  
Mature Embryo ◽  
Globular Embryo ◽  
Primary Endosperm Nucleus ◽  
Oil Glands ◽  
Polygonum Type ◽  
History Of

In Darwinia the floral parts are differentiated in a "calyx-orolla-gynoeciumandroecium" sequence. In individual buds stages of microsporogenesis markedly precede corresponding stages of megasporogenesis. The anther is tetrasporangiate with all sporangia lying in one plane. The secretory tapetum is one- to three-layered within the same microsporangium and a large number of Ubisch bodies are formed. The anthers dehisce by minute lateral pores and an ingenious mechanism helps disperse the twocelled pollen grains. A basal placenta in the single loculus of the ovary bears four ovules in D. micropetala and two in D. fascicularis. In both species, however, only one ovule is functional after fertilization. The fully grown ovules are anatropous, crassinucellar, and bitegmic; the inner integument forms the micropyle. The parietal tissue is most massive at the completion of megasporogenesis but is progressively destroyed later. The embryo sac follows the Polygonum type of developnlent and when mature is five-nucleate, the three antipodals being ephemeral. Following fertilization, the primary endosperm nucleus divides before the zygote. Subsequent nuclear divisions in the endosperm mother cell are synchronous and lead to a free-nuclear endosperm which becomes secondarily cellular, starting from the micropylar end at the time the globular embryo assumes an elongated shape. Embryogeny is irregular and the mature embryo is straight with a massive radicle and a hypocotyl which terminates in two barely recognizable cotyledons. Sometimes the minute cotyledons are borne on a narrow neck-like extension of the hypocotyl. A suspensor is absent. Both integuments are represented in the seed coat and only the outer layer of the outer and the inner layer of the inner integuments, with their thick-walled tanniniferous cells, remain in the fully grown seed. The ovary wall is demarcated into an outer zone containing oil glands surrounded by cells containing a tannin-like substance and an inner zone of spongy parenchyma. In the fruit this spongy zone breaks down completely but the outer zone is retained. The two species of Darwinia, while closely resembling each other in their embryology, differ significantly from other Myrtaceae. However, no taxonomic conclusions are drawn at this stage, pending enquiry into the life history of other members of the tribe Chamaelaucieae.

scholarly journals Construction of a weight-based seed sorting system for the third-generation hybrid rice

Rice ◽  
2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jianxin Wu ◽  
Shijun Qiu ◽  
Menglong Wang ◽  
Chunjue Xu ◽  
Xing Wang Deng ◽  
...  
Keyword(s):  
Hybrid Rice ◽  
Pollen Grains ◽  
Third Generation ◽  
Male Sterile ◽  
Specific Expression ◽  
The Third ◽  
Genes Encoding ◽  
Wild Type Male ◽  
Sorting System ◽  
Generation Hybrid

Abstract Background The third-generation hybrid rice technology can be constructed by transforming a recessive nuclear male sterile (NMS) mutant with a transgenic cassette containing three functional modules: the wild type male fertility gene to restore the fertility of the mutant, the pollen killer gene that specifically kills the pollen grains carrying the transgene, and the red fluorescence protein (RFP) gene to mark the transgenic seed (maintainer). The transgenic plant produces 1:1 NMS seeds and maintainer seeds that can be distinguished by the RFP signal. However, the RFP signals in the partially filled or pathogen-infected maintainer seeds are often too weak to be detected by RFP-based seed sorting machine, resulting in intermingling of the maintainer seeds with NMS seeds. Results Here we constructed a weight-based seed sorting system for the third-generation hybrid rice technology by silencing the genes encoding ADP-glucose pyrophosphorylase (AGP) essential for endosperm starch biosynthesis via endosperm-specific expression of artificial microRNAs (amiRNAs). In this system, the NMS seeds have normal endosperm and are heavy, but the maintainer seeds have shrunken endosperms and are light-weighted. The maintainer seeds can be easily and accurately sorted out from the NMS seeds by weight-sorting machines, so pure and fully filled NMS seeds are available. Conclusions The weight-based seed sorting system shows obvious advantages over the RFP-based seed sorting system in accuracy, efficiency, and cost for propagation of pure male sterile seeds. These characteristics will significantly increase the value and transgenic safety of the third-generation hybrid rice technology.

Calibration of LgrassFlo, a new model of perennial grass phenology in response to temperature and photoperiod.

2021 ◽  
Author(s):  
Simon Rouet ◽  
Jean-Louis Durand ◽  
Didier Combes ◽  
Abraham Escobar-Gutierrez ◽  
Romain Barillot
Keyword(s):  
Genetic Diversity ◽  
Plant Architecture ◽  
Floral Induction ◽  
Perennial Grass ◽  
Heading Date ◽  
Reproductive Development ◽  
Perennial Grasses ◽  
Floral Transition ◽  
New Model ◽  
Primary Induction

&lt;p&gt;In perennial grasses, the reproductive development encompasses several phenological events, such as apex induction, floral transition, heading and flowering, that deeply affect biomass production, forage quality and plant perenniality. Despite the importance of perennial grasses in agricultural systems and natural ecosystems, we still lack accurate models predicting the reproductive development and its consequences on plant growth and grassland management. Most of available models implements a fixed scheduling of the reproductive development expressed either in thermal time or in calendar time. The progressive completion of floral induction and the effects of environmental factors are generally poorly described. In addition, the vegetative and reproductive developments are represented as independent and successive phases. In the present work, we introduce the new model LgrassFlo, which simulates the reproductive development of perennial grasses in interaction with plant vegetative development and considering the effects of environmental conditions on floral induction.&lt;/p&gt;&lt;p&gt;LgrassFlo simulates the canopy as the dynamics of a collection of individual plants, each being composed of one or more tillers. The 3D description of leaf growth and tillering is based on a functional-structural plant model of perennial ryegrass (Lgrass). We developed a new model of floral induction describing the progression of the primary and secondary induction of each apex of the plant according to (i) the daily temperature, (ii) photoperiod and (iii) plant architecture. This model was coupled to Lgrass, the model ensemble being called LgrassFlo. During apex induction, LgrassFlo accounts for an increase in the rates of leaf primordia initiation and leaf elongation. After floral transition, we assume that the apex only initiates spikelet primordia and that internodes start to elongate. LgrassFlo simulates the date of floral transition, the final number of leaves and the heading date based on a 3D representation of plant architecture.&lt;/p&gt;&lt;p&gt;A specific experiment was carried out in order to calibrate LgrassFlo on data describing the vegetative and reproductive development of three &lt;em&gt;Lolium perenne&lt;/em&gt; cultivars contrasted for their precocity and exposed to four inductive conditions in growth chambers. The first three conditions consisted in a period allowing for primary induction (low temperature &amp;#8211; short day) followed by a period allowing for secondary induction (high temperature &amp;#8211; long day), the two periods being spaced by a non-inductive period (high temperature - short day) of 0, 3 or 6 weeks. In the fourth condition, plants were not exposed to conditions allowing for the primary induction. A set of vegetative and reproductive parameters were estimated for each individual plant of the experiment. The parameter values were independent of the experimental treatment but showed a large genetic diversity both between and within varieties. Using this calibration, LgrassFlo satisfactorily predicted the observed diversity in final leaf number and heading date.&lt;/p&gt;&lt;p&gt;The present model is a step forward towards a better prediction of perennial grass phenology in actual and future climatic conditions. In this respect, the model is being currently used to simulate the observed genetic diversity in the heading date of several Lolium perenne cultivars grown in contrasted temperate climates over the last 15 years.&lt;/p&gt;

Tagesperiodische antagonistische Schwankungen der Blauviolett- und Gelbrot-Empfindlichkeit als Grundlage der photoperiodischen Diapause-Induktion bei Pieris brassicae

1960 ◽  
Vol 15 (4) ◽  
pp. 205-213 ◽  
Author(s):  
Erwin Bünning ◽  
Gabriele Joerrens
Keyword(s):  
Dark Period ◽  
Red Light ◽  
Pieris Brassicae ◽  
Light Period ◽  
Measuring Process ◽  
The Third ◽  
Long Day ◽  
Critical Daylength ◽  
Qualitative Responses ◽  
Short Days

In Pieris brassicae, diapause is inhibited if long-day conditions are imposed during and immediately after the third molting. The critical daylength is approximately 14 hours. Under short-day conditions with a main light period of 6 or 12 hours’ duration, supplementary light given in the period from 14 to 16 hours after the beginning of the main light period will inhibit diapause. In contrast to this effect of late exposures to light, light given from 1 to 12 hours after the beginning of the main light period promotes diapause. Experiments with extremely long light periods (10—35 hours), but always with a dark period of 10 hours, show that these diurnal fluctuations in quantitative and qualitative responses to light can continue endogenously for several days. Thus, this time-measuring process operates through the mechanism of endogenous diurnal oscillations in just the same way as do photoperiodic reactions in plants.The inhibition of diapause by light in the second half of the diurnal oscillation (under long days or by light interruptions in the dark period) and the promotion by light in the first half (under short days) occur only with light of short wavelengths: ultraviolet, violet, and blue up to about 550 mμ. Yellow and red light act in the opposite fashion, giving diapause inhibition in the first half of the cycle and promotion in the second half. In white light the violet reaction predominates, so that diapause is promoted by short days and inhibited by long days.

scholarly journals Flowering dynamics and pollen production of Laburnum anagyroides Med. under the conditions of south-eastern Poland

2013 ◽  
Vol 57 (2) ◽  
pp. 103-115 ◽  
Author(s):  
Ernest Stawiarz ◽  
Anna Wróblewska
Keyword(s):  
Pollen Grains ◽  
Average Weight ◽  
Pollen Production ◽  
Full Bloom ◽  
Flowering Duration ◽  
The Third ◽  
Laburnum Anagyroides ◽  
Golden Yellow ◽  
Single Flower ◽  
The Common

Abstract A study on the flowering biology and pollen production of the common laburnum (Laburnum anagyroides Med.) was conducted under the conditions of Lublin during the period 2004 - 2006. The flowering of this species began in the second 10-day period of May and lasted for 2.5 - 4 weeks. The flowers of common laburnum are borne in showy golden-yellow pendulous racemes. They develop successively, starting from the base and moving to the tip of an inflorescence. During the growing season, one shrub produces 800 to 3200 racemes, with 14 to 35 flowers in a single raceme. On average, the flowering duration for a raceme was 12.8 days and 8.7 days for a single flower. Throughout the study years, the shrubs proved to be most attractive in the third 10-day period of May when they reached full bloom. The average weight of pollen produced was 6.08 mg per 10 flowers of Laburnum anagyroides, 14.02 mg per raceme, and 26.0 g per shrub. Pollen grains reached average dimensions of 24.01 μm × 24.26 μm.

scholarly journals Barleria gandhii, a new name for Barleria pauciflora (Acanthaceae)

Phytotaxa ◽  
2015 ◽  
Vol 204 (4) ◽  
pp. 300
Author(s):  
RAMALINGAM KOTTAIMUTHU
Keyword(s):  
South Africa ◽  
Species Diversity ◽  
Calcium Oxalate ◽  
Pollen Grains ◽  
Epidermal Cells ◽  
Calcium Oxalate Crystals ◽  
Tropical Africa ◽  
New Name ◽  
Oxalate Crystals

Barleria Linnaeus (1753: 636) is a pantropical genus comprising about 250–300 species (Balkwill & Balkwill 1998, Darbyshire et al. 2012), with its greatest centre of species diversity in tropical Africa, followed by South Africa and Asia (Balkwill & Balkwill 1998, Darbyshire 2010). It can be easily distinguished from other genera of Acanthaceae by a combination of three characters: a 4-partite calyx with 2 large outer (anterior and posterior) segments and 2 smaller inner (lateral) ones, spheroidal, pollen grains with coarsely reticulate exine and the predominance of double cystoliths (calcium oxalate crystals) in the epidermal cells (Balkwill & Balkwill 1997, Champluvier 2011, Darbyshire 2010).

Four Fragments of the Hebrew Bible from Antinoopolis, P.Ant. 47–50

2019 ◽  
Vol 105 (2) ◽  
pp. 209-216
Author(s):  
Jelle Verburg ◽  
Tal Ilan ◽  
Jan Joosten
Keyword(s):  
Hebrew Bible ◽  
Critical Edition ◽  
Late Antiquity ◽  
Dark Period ◽  
Dead Sea Scrolls ◽  
Dead Sea ◽  
The Third ◽  
Masoretic Text ◽  
Cairo Genizah ◽  
Epigraphic Evidence

An expedition of the Egypt Exploration Society in 1913–14 discovered four fragments of the Hebrew Bible (from the books of Kings and Job). This article presents the first critical edition of the fragments. With a few minor exceptions, the fragments conform to the Masoretic Text. The possible datings of these fragments range from the third to the early eighth centuries ce. Very little is known about the transmission of the text of the Hebrew Bible in the so-called ‘silent’ or ‘dark’ period between the Dead Sea Scrolls and the Cairo Genizah. The fragments also testify to the presence of a Jewish community in Egypt – which was virtually eradicated after the revolt of 115–17 ce. The article gives a brief overview of the extant documentary and epigraphic evidence to reconstruct the forgotten story of Jews at Antinoopolis in Late Antiquity.

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