Division Of Pollen Mother Cells Research Articles

Abnormal expression of LiASY1 and LiDMC1 is the main cause of sterility in F1 hybrids developed from Lagerstroemia speciosa and Lagerstroemia indica ‘Ebony Embers’

Lagerstroemia × ‘Xiaoxiang Huaxiu’ (an F1 hybrid of Lagerstroemia speciosa and Lagerstroemia indica ‘Ebony Embers’) exhibits significant sterility. Cytological studies have revealed numerous abnormal chromosomal behaviors during the meiotic division of pollen mother cells in L. × ‘Xiaoxiang Huaxiu’. Transcriptome sequencing identified that LiDMC1 and LiASY1 were expressed at very low levels in ‘Xiaoxiang Huaxiu’. To further verify whether the abnormal expression of LiDMC1 and LiASY1 was the fundamental cause of sterility in ‘Xiaoxiang Huaxiu’, we cloned the full-length gene sequences of LiDMC1 and LiASY1 from ‘Ebony Embers’. Using VIGS (virus-induced gene silencing) technology, pTRV1 and pTRV2 gene silencing vectors were employed to silence LiDMC1 and LiASY1 in the paternal parent ‘Ebony Embers’. The results indicated that in the double-silenced lines of ‘Ebony Embers’, the cytoplasm sizes of different tetrads during the tetrad stage varied significantly. There was a notable proportion of polyads, binucleate cells with micronuclei, and pentads. Additionally, pollen diameter varied significantly, closely resembling the sterility observed in ‘Xiaoxiang Huaxiu’. Pollen viability in the double-silenced ‘Ebony Embers’ decreased by 22.8%. This study demonstrates that the low expression of LiDMC1 and LiASY1 leads to abnormal microspore development in ‘Ebony Embers’, and their low expression is the cause of sterility in ‘Xiaoxiang Huaxiu’.

Two novel meiotic restitution mechanisms in haploid maize (Zea mays L.)

Two original mechanisms of nuclear restitution related to different processes of meiotic division of pollen mother cells (PMCs) have been found in male meiosis of the lines of maize haploids no. 2903 and no. 2904. The first mechanism, which is characteristic of haploid no. 2903, consists in spindle deformation (bend) in the conventional metaphase-anaphase I. This leads to asymmetric incomplete cytokinesis with daughter cell membranes in the form of incisions on the mother cell membrane. As a result, the chromosomes of the daughter nuclei are combined into a common spindle during the second meiotic division, and a dyad of haploid microspores is formed at the tetrad stage. The frequency of this abnormality is about 50%. The second restitution mechanism, which has been observed in PMCs of haploid no. 2904, results from disturbance of the fusion of membrane vesicles (plastosomes) at the moment of formation of daughter cell membranes and completion of cytokinesis in the first meiotic division. This type of cell division yields a binuclear monad. In the second meiotic division, the chromosomes of the daughter nuclei form a common spindle, and meiosis results in a dyad of haploid microspores. The frequency of this abnormality is as high as 15%. As a result, haploid lines no. 2903 and no. 2904 partly restore fertility.

Feed‐back regulation of successive meiotic cytokinesis

The paper considers a number of abnormal phenotypes with impaired temporal regulation of cytokinesis during the meiotic division of pollen mother cells. The phenomenon of "non-stop" cytokinesis with blocked arrest of the phragmoplast centrifugal motion and cell plate growth as well as incomplete and premature cytokinesis are described. The obtained data suggested a model for regulation of the processes involved in the arrest of the main cytokinesis processes during its completion in the plant meiosis.

Induction of Male Sterility in Wheat by Meiotic-Stage Water Deficit Is Preceded by a Decline in Invertase Activity and Changes in Carbohydrate Metabolism in Anthers.

Water deficit during meiosis in pollen mother cells of wheat (Triticum aestivum L.) induces male sterility, which can reduce grain set by 40 to 50%. In plants stressed during meiosis and then rewatered, division of pollen mother cells proceeds normally but subsequent pollen development is arrested 3 or 4 d later. An inhibition of starch accumulation within the pollen grain suggested that an alteration in carbohydrate metabolism or assimilate supply may be involved in pollen abortion. We measured levels of various carbohydrates and activities of key enzymes of Suc metabolism and starch synthesis at different stages of pollen development in anthers collected from well-watered and water-stressed plants. Compared to controls, soluble sugars increased in anthers stressed during meiosis, then decreased at later poststress stages. Sucrose and myoinositol accounted for part of the sugar accumulation. The activity of soluble acid invertase declined 4-fold during the stress period and never recovered thereafter. Sucrose synthase activity during starch accumulation in pollen was also lower in the anthers of plants stressed at meiosis. Stress had little negative effect on the activities of ADP-glucose pyrophosphorylase or soluble and granule-bound starch synthase during starch accumulation in pollen, although at the earlier stages, ADP-glucose pyrophosphorylase activity in stressed anthers was slightly lower compared to controls. The results suggest that carbohydrate starvation per se and inhibition of the enzymes of starch synthesis probably were not responsible for the stress-induced pollen abortion. Instead, an inability to metabolize incoming sucrose to hexoses may be involved in this developmental lesion.

Effects of Air-Temperature and Water-Temperature at Each Stage of the Growth of Lowland Rice : II. Effect of air-temperature and water-temperature on the heading date

Growing the rice plants under various conditions of some possible combinations of daytime air-temperatures (AD : 26, 20 and 14°C), the daytime water-temperatures (WD : 26, 20 and 14°C), the nocturnal air-temperatures (AN : 20, 14 and 8°C), the nocturnal water-temperatures (WN : 20, 14 and 8°C) and the number of days of treatment (P : 3, 6 and 9 days), the authors examined their main effects and interactions on the heading date. The rice variety Eiko was used. The daytime was settled for eight hours from 9.00 a.m. to 5.00 p.m. and the night-time was settled for sixteen hours from 5.00 p.m. to 9.00 a.m. of the next day. The water was kept four cm. in depth above the soil surface in pots. The experimental design was 35 factorial in 81 units (1/3 replicate) with one block and defining contrasts 1=ADWDANWN P. The results were summarized as follows; 1. At the fourth leaf stage (T1; the transplanting time), the main effects of WD, WN and P were significant at 0.1% level and all the other were not significant (table 2). And regardless of the difference of WN, it was inferred that WD of 21°C hastened the heading date (fig. 1-T1(P3)). 2. At the seventh leaf stage (T2; about ten days before the differentiating stage of first bract primordia), the main effects of AD, WD, AN and WN and the two-factor interactions of AD × P, AN × WN and AN × P were significant. The contour lines of each date of heading based on WD and WN were almost straight and parallel with the line of mean water-temperature for nine days treatment (fig. 1-T2 (P3)). On the other hand, the contour lines of each date of heading based on AD and AN were curved. And regardless of the difference of AN, it was inferred that AD of 20°C hastened the heading date (fig. 2-T2 (P3)). Moreover, T2 was considered to be the most sensitive stage to temperature, because the heading date and the total leaf number on the main stem were most variable by both air- and water-temperature among all the treatment stages. 3. At the stages of nine leaves (T3; the differentiating stage of first bract primordia) and ten leaves (T4; the middle differentiating stage of primary branch primordia), the main effects of each factor and their interactions were similar to those of T2, but the strengths were weaker than those of T2 (table 2, 3 and 4). 4. At the thirteenth leaf (flgg leaf) stage (T5; the stage of reduction division of pollen mother cells), the main effects of AD, AN and P and the two-factor interaction of AN × P were significant greatly (table 2). The contour lines of each date of heading based on AD and AN were almost straight and parallel with the line of mean air-temperature (fig. 2-T5 (P3)).

Effects of Air-Temperature and Water-Temperature at Each Stage of the Growth of Lowland Rice : I. Effect of air-temperature and water-temperature on the percentage of sterile grains

Growing the rice plants under each condition of some possible combinations of the daytime air-temperatures (AD: 26, 20 and 14°C), the daytime water-temperatures (WD: 26, 20 and 14°C), the nocturnal air-temperatures (AN: 20, 14 and 8°C), the nocturnal water-temperatures (WN:20, 14 and 8°C) and the number of days of treatment (P: 3, 6 and 9 days) at each stage of growth, the autliors examined their main effects and interactions on the percentage of sterile grains. The daytime was settled for eight hours from 9.00 a.m. to 5.00 p.m. and the night-time was settled for sixteen hours from 5.00 p.m. to 9.00 a.m. of the following day. The depth of water was kept in four cm. above the soil surface in pots. The experimental design was 35 factorial in 81 units (1/3 replicate) with one block and defining contrasts 1=ADWDANWN2P. The results were summarized as follows; 1. At the differentiating stage of first bract primordia (T3), all the main effects and their two-factor interactions were not significant (table 4). 2. At the middle differentiating stage of primary branch primordia (T4), only the main effect of AD was significant at 5% level. However, that was not considered to be important because the differences of the percentage of sterile grains among them were smaller than 3%(tables 3 and 4). 3. At the stage of reduction division of pollen mother cells (T5), the main effects of AD, AN and P and all of their two-factor interactions were significant at 0.1 or 1% levels. Moreover, the effects of WD, WD × AN and WD × WN were also significant at 5% level. The contour lines of each pefcentage of sterile grains based on AD and AN were straight and parallel with the line of mean air temperature for three day treatment (fig. la). On the other hand, the contour lines for six and nine day treatments were curve together (fig. 1b-c). 4. At the head emergernce stage (T6), the effects of AD, AN, P, and AN × P and AN × P were significant at 0.1% level. However, for three day treatment, AD and AN didn't affect the percentage of sterile grains. For six and nine day treatment, AD and AN were effective and their contour lines of each percentage of sterile grains were curve (fig. 2b-c). 5. The optimum ranges between AD and AN to minimize the percentage of sterile grains for each mean air-temperature were found in all the cases in which the contour lines were curve. The lower the mean air-temperature became, the bigger the optimum range between AD and AN became in most cases. Moreover, the optimum combinations of AD and AN to minimize the percentage of sterile grains were found to be about 24-20°C in all cases (fig. 1∼2).

Anatomía reproductiva en flores estaminadas y pistiladas de Allophylus edulis (Sapindaceae)

Se estudió la esporogénesis y gametogénesis de flores estaminadas y pistiladas de Allophylus edulis (Sapindaceae). La anteras jóvenes son similares en ambos tipos de flores, comparten el tipo básico de desarrollo anteral; presentan epidermis, endotecio con células binucleadas, dos capas medias, y tapete de tipo secretor, con células binucleadas. La microsporogénesis es normal, la división de las células madres de las micrósporas es simultánea y las tétrades son tetraédricas y decusadas. La antera madura en flores estaminadas presenta células epidérmicas adelgazadas a nivel del estomio y el endotecio con engrosamientos fibrosos. Se aprecia un único lóculo por teca por disolución del septo y los granos de polen son liberados al estado 2-celular, éstos son triporados o tetraporados. El gineceo está reducido a un pistilodio tricarpelar, trilocular, con un óvulo por lóculo. El óvulo degenera antes de que ocurra la meiosis. La antera madura de las flores pistiladas difiere anatómicamente de la de las flores estaminadas. El endotecio no desarrolla engrosamientos fibrosos, las capas medias y el tapete persisten, y el estomio no es funcional; las anteras son indehiscentes. El gineceo de las flores pistiladas, presentan ovario tricarpelar y trilocular. Cada lóculo contiene un óvulo hemianátropo, bitegumentado y crasinucelado, con obturador desarrollado; el megagametófito es de tipo Polygonum. Se discuten los resultados obtenidos en relación a lo conocido para la familia.

COMPARATIVE MORPHOLOGY AND PHYLOGENY OF THE RANALES

SUMMARYComparative morphological studies of woody Ranales have established the primitive status of the group and hence their key place in angiosperm phylogeny. Significant advances in our knowledge of some ranalian families have been made in recent years. An attempt is made in the present review to bring together a range of morphological data (vegetative and floral anatomy, palynology and embryology) on the Ranales (sensu lato), with particular reference to research work published after the publication of Eames's (1961) book, and to discuss the relationships of the families.Recent ontogenetic studies have shown that the carpel of Drimys is ascidial and not conduplicate as earlier suggested. The inclusion of Degeneria in the Winteraceae is not supported by morphological data.Melville's gonophyll theory has been shown to be inapplicable to the magnoliaceous flower.The pollen of Schisandra is interpreted as derived and specialized rather than primitive as previously supposed. The removal of Schisandra from Magnoliaceae is upheld by morphological evidence. Recent morphological studies do not support a close relationship between Schisandraceae and Illiciaceae suggested by earlier authors.The Canellaceae shows similarities to Winteraceae, Magnoliaceae, Illiciaceae, Eupteleaceae and Myristicaceae.Transitional types of division of pollen mother cells found in Winteraceae, Schisandraceae and Annonaceae and their probable phylogenetic significance have been discussed.The Annonaceae, Winteraceae, Degeneriaceae, Magnoliaceae, Schisandraceae and Cercidiphyllaceae share several embryological features in addition to similarities in floral structure.Ruminate endosperm is regarded either as an archaic feature retained in some taxa or as a later and parallel development in others. Thus its value in assessing relationships seems to be doubtful.Myristicaceae has been shown to be closely related neither to the the Annonaceae nor to the Lauraceae.The suggested relationship of Eupomatiaceae to Annonaceae is not supported by palynology.Floral cortical vascular systems in Magnoliaceae, Annonaceae, Calycanthaceae and Myristicaceae have been compared and it is concluded that they may be vestigial structures.A great deal of similarity has been found between Lauraceae and Calycanthaceae in wood, node, flower structure and embryology.Further floral anatomical evidence has been adduced to support the removal of Scyphostegia from Monimiaceae.The Hernandiaceae show similarities to some members of Monimiaceae while the Gyrocarpaceae resemble the Lauraceae, Gomortegaceae and certain other genera of Monimiaceae.Available evidence from wood and floral anatomy and embryology indicates close relationships among Lauraceae, Monimiaceae and Hernandiaceae.Vegetative and floral anatomical and embryological data seem to indicate a place for the Chloranthaceae in the ranalian complex.Recent anatomical studies in the Nymphaeaceae show that the floral structure is of a primitive type with similarities to the woody Ranales. Available morphological evidence is considered inadequate to express an opinion on the splitting of the family.Ceratophyllaceae is regarded as a highly reduced ranalian family derived most probably from a nymphaeaceous stock.The gynoecium in Berberidaceae is interpreted as monocarpellate. No evidence has been found to support the tricarpellate view. Berberidaceae, Lardizabalaceae and Menispermaceae share several embryological features, while at the same time showing evidence of specialization, each in its own way. Thus they might have arisen from a common stock and early diverged along different lines.The occurrence of several types of embryo sac in Ranunculaceae may well be an indication of specialization, but their probable taxonomic value, if any, is not yet clear.The occurrence of numerous primitive features in Paeonia has been suggested as an argument for its retention in the Ranales.No evidence has been found to preclude the inclusion of Dilleniaceae in the Ranales. On the other hand, as opposed to similarities in wood and pollen characters between Dilleniaceae and Theaceae, floral anatomical and embryological features offer a sharp contrast between the two.The Ranales are believed to be polyphyletic. It has been tentatively suggested that two major phyletic lines may be recognized in each of the woody and herbaceous series: the magnolialian and lauralian lines in the former and the nymphaealian and berberidalian lines in the latter.

Studies on the Monimiaceae. III. Gametophyte development of Laurelia novae-zelandiae A. Cunn. (subfamily Atherospermoideae)

Floral ontogeny and gametophyte development of the New Zealand endemic species Laurelia novae-zelandiae is described. The microsporangium has three to five wall layers inside the epidermis, including a typically thickened endothecium and a tapetum of the secretory type in which the cells become binucleate during the first meiotic division of pollen mother cells. Cytokinesis of pollen mother cells is of an unusual type in which centrifugal cell plates do not develop until the end of meiosis 11. The generative cell of the pollen grain is cut off against what represents a radial wall of the grain with reference to the tetrad stage. Pollen is two- or three-celled when shed. Ovules are bitegmic, crassinucellate, and anatropous with a Polygonum type of embryo sac development.

Studies on the Monimiaceae. I. Floral morphology and gametophyte development of Hedycarya arborea J.R. et.G. Forst. (subfamily Monimioideae)

Inflorescences, flowers, and floral vascularization of the New Zealand endemic species Hedycarya arborea are described. Varying carpel vasculature suggests derivation of the uniovulate condition in Hedycarya from ancestors having multiovulate carpels with ovules in two rows, Floral ontogeny is described and it is noted that the terminal stigmatic region of the carpel develops from a solid terminal meristem, in contrast to many woody Ranales in which the stigma consists of crests surrounding the carpel cleft. The stigmatic surface is a mass of globose projections, apparently serving as pollen traps. No comparable type of stigma has previously been reported in the woody Ranales. The microsporangium has a typically thickened endothecium and a tapetum of the secretory type with tapetal cells becoming binucleate during the first meiotic division of pollen mother cells. Pollen mother cell division is of the successive type with cytokinesis by centrifugally extending cell plates. The generative cell is cut off towards the distal face of the microspore. The pollen, in permanent tetrads, is shed in the two-celled condition. Ovules are bitegmic, crassinucellate, and anatropous with a Polygonum type of embryo sac development. Some comparisons are made with the Australian species Hedycarya angustifolia.

Floral morphology, embryology, and relationships of the Berberidaceae.

The floral morphology and development of the gametophytes in Berberis umbellata and Mahonia leschenaultii have been studied. All the perianth members have three traces each in B. umbellata while in M. leschenaultii the members of the outer three whorls have five veins each and those of the fourth three veins each. The vascular supply for the inner two whorls of perianth and the stamens arises as conjoint traces. The wall of the gynoecium is traversed by numerous bundles with some concentrated in the placental region. The dorsal and ventral bundles are differentiated in M. leschenaultii but not in B. umbellata. The tricarpellary interpretation of the gynoecium is shown to be unconvincing. The gynoecium is regarded as monocarpellary. The mature anther wall is five-layered including the epidermis, of which the innermost layer forms the tapetum of secretory type. The tapetal cells are four to eight-nucleate. The hypodermal wall layer develops into a fibrous endothecium in M. leschenaultii. In B. urnbellata, the endothecium develops U-shaped thickenings. Division of pollen mother cells is successive. Pollen tetrads are usually isobilateral. Mature pollen grains are three-colpate and two-celled. The ovule is anatropous, bitegmic, and crassinucellate. In B. umbellata, a rudimentary aril is formed as an outgrowth of the funiculus. The single hypodermal archesporial cell in the young ovule cuts off a parietal cell. Development of the embryo sac is of the Polygonum type. The synergids show filiform apparatus and are persistent. The antipodals are large and persistent in M. leschenaultii and ephemeral in B. umbellata. The relationships of the Berberidaceae (sensu Hutchinson 1959) to the Menispermaceae, Lardizabalaceae, and the Ranunculaceae (sensu lato) are discussed.

The Progeny of Tetraploid Tomatoes (Preliminary report)

Forty heteroploid tomatoes arised out of five hundred seeds, which were obtained from the regenerated tetraploids produced by the decapitation-method. They could be already noticed in the seedling stage for the slowness of germination and the abnormality of cotyledons. The dwarfness and bushy form are two remarkable characteristics of the mature plants and their fruit-setting is very rare or none. The somatic chromosome numbers of the heteroploid plants so far examined are 49, 50, 51, 52, 53, and 54; namely 4n+1, 4n+2, 4n+3, 4n+4, 4n+5 and 4n+6 respectively. The heteroploidy may be caused by the gamates, which have super diploid chromosome numbers on the consequence of irregular division of pollen mother cells in the tetraploid tomatoes.

染色體ノニ次的螺旋構造ニ就テ

The double-coiled spiral or spiral-within-spiral structure of chromosomes first announced by Prof. FUJII (1926) to be found in chromosomes in the heterotype division of pollen mother cells in Tradescantia virginica and recently also reported by ISHII (1931) in his study of chromosomes in the same plant, was confirmed by a new method in which pollen mother cells extruded from the anther are exposed on a cover glass with a very small drop of a cane sugar solution (3%) to a mmonia vapour for a few seconds before being stained with acetocarmine (Fig.1). While in Tradescantia virginica this structure is observable only in chromosomes in the heterotype division, it is also found, according to Mr. SHINKE, in the homotype division in Sagittaria Aginashi in which, contrary to the case of Tradescantia virginica, there is no remarkable difference in shape between chromatids in the heterotype and those in the homotype division. The same structure is also recognizable from SHINKE'S microphotographs in chromosomes in the heterotype division in Lilium tigrinum and Hosta Sieboldiaua (SHINKE, 1930, Figs. 1 and 7).In Tradescantia virginica the portion where one chromosome is linked with another often shows that the spiral of the higher order is double in the metaphase, consisting of two of the spirals of the lower order which may separate from each other to a certain extent in the anaphase (Figs. 2 and 3. Comp. also Figs. 4 and 5).The genetical importance of this structure in reference to the peculiar shape of the chromosomes in the heterotype division has been pointed out by Prof. FUJII (1926), the double-coiled spiral being taken as the source of this peculiar shape (Comp. Figs. 1-6 with Figs. 6 and 7).The coiling thread or chromonema was traced to the interphasic state of the nucleus in ordinary acetocarmine preparations (Figs. 8, 9 and 10) as well as in the living state of the cells (Figs. 11 and 12), liquid paraffin being used as medium.

すいばノ細胞學的研究續報 (豫報)

I. The development of the embryosac and embryo of R. Acetosa.The formation of embryosac of R. Acetosa proceeds quite normally. In the diakinesis and the heterotypic metaphase of megaspore mother cells, seven gemini are seen. One of them is much larger than the others and is considered to be the pair of X-chromosomes. After the reducing division, four usual megaspores are formed. The innermost one among them is functional and forms later an 8-nucleate normal embryosac. The double fertilization occurs in the usual manner. The development of fertilized eggs is quite normal. Two different types of embryo, namely with 14 and 15 chromosomes, have been observed.II. The occurrence of the triploid female of R. Acetosa.Triploid, 22-chromosomal intersexual plants were described in my previous paper. During the examination of the somatic chromosomes of a number of wild female plants, one 21-chromosomal, triploid female has been found. The chromosomal formula of this plant should be perhaps as follows; 21=18+3X=_??_(12+2X)+_??_(6+X).III. Reducing division of the triploid intersexual plant of R. Acetosa.The meiosis of the intersexual plants of R. Acetosa proceeds not quite normally, especially in the potted plants. The material obtained from a plant growing wild has shown, however, comparatively good figures. The number of chromosomes in.somatic cell of that plant has been determined to be 22(=18+2X+2Y). In the early metaphase of the heterotypic nuclear division of pollen mother cells, there appear six trivalents, one large ring-shaped XX-pair and two separated Y-elements. The division of these chromosomal elements shows some irregularities but they are distributed by chance almost equally in number to the opposite poles. After the abnormal second division four abortive pollens are formed.IV. Diploid nuclear plates in pollen mother cells of R. Acetosa.In the materials fixed in the early spring of this year, nuclear plates with unreduced number (viz. 15) are often observed among the normal ones during the heterotypic nuclear division of the pollen mother cells. These 15 chromosomes are split normally in the anaphase. The formation of these diploid chromosomal gamates may be related to the origin of the triploid and tetraploid plants often found in the fields.V. Chromosomes of R. vesicarius.R. vesicarius is an annual hermaphrodite plant, belonging to subgenus Acetosa. The diploid and haploid numbers of chromosomes of this plant are 18 and 9 respectively. The basal number 9 in the genus Rumex had not previously been found in the subgenus Acetosa, nor in the subgenus Lapathum.The haploid number of chromosomes of Oxylia elatior has also been determined to be 7 in the reducing division of pollen mother cells.