Meiosis In PMC Research Articles

Orf165 is associated with cytoplasmic male sterility in pepper.

Cytoplasmic male sterility (CMS) is a maternally inherited trait that derives from the inability to produce functional pollen in higher plants. CMS results from recombination of the mitochondrial genome. However, understanding of the molecular mechanism of CMS in pepper is limited. In this study, comparative transcriptomic analyses were performed using a near-isogenic CMS line 14A (CMS-14A) and a maintainer line 14B (ML-14B) as experimental materials. A total of 17,349 differentially expressed genes were detected between CMS-14A and ML-14B at the PMC meiosis stage. Among them, six unigenes associated with CMS and 108 unigenes involved in energy metabolism were identified. The gene orf165 was found in CMS-14A. When orf165 was introduced into ML-14B, almost 30% of transgenic plants were CMS. In addition, orf165 expression in transgenic CMS plants resulted in abnormal function of some genes involved in energy metabolism. When orf165 in transgenic CMS plant was silenced, the resulted orf165-silenced plant was male fertile and the expression patterns of some genes associated with energy metabolism were similar to ML-14B. Thus, we confirmed that orf165 influenced CMS in pepper.

Mutagenic activity of dimethyl sulfate on meiosis in M1 sunflower

Analysis of changes in the cell nucleus, and especially in its most important structural components – chromosomes, is a reliable test to assess mutagenic susceptibility of plants.The aim and tasks of the study. The study purpose was to evaluate the effect of mutagen on meiosis in M1 sunflower cells.According to the intended purpose, we set the following objectives: To evaluate the effect on supermutagen on the frequency of meiosis disorders, depending on concentration; to compare the incidence of impaired cells in M1 with the control.Materials and methods. Two homozygous lines – sterility fixers and 2 lines – pollen fertility restorers bred at the Plant Production Institute nd. a VYa Yuriev were pretreated with chemical mutagen dimethyl sulfate at the concentrations of 0.01% and 0.05% and used as starting material. The controls was dry untreated seeds.To study meiosis in M1 sunflower, we separated calathidium segments (d = 2-3 cm) with anthers, fixed them in acetic alcohol (1: 3) for 24 hours. Then we washed them in ethanol three times and stored in 70% ethanol at + 4 ° C. Chromosomes of pollen mother cells were stained in 2% aceto-orcein. Meiosis was studied in temporary preparations squashed in a drop of 40% acetic acid.Results and discussion. Meiosis disorders in pollen mother cells were mainly expressed in chromosome lag during metaphase or in chromosome disjunction during anaphase. In the 2nd meiotic division, the chromosome abnormalities observed were essentially the same as those in the 1st division. Despite the presence of abnormalities in meiosis, externally normally developed tetrads prevailed in mutant sunflower lines. In addition, we observed monads, dyads, triads, pentads, but their percentage was negligible. Having analyzed the data on M1 sunflower treated with dimethyl sulfate at the concentrations of 0.01% and 0.05%, we can conclude that mutagen significantly affects meiosis in comparison with the control, since the percentage of impaired cells was high as compared to the control. For example, in line Х06-135В the incidence of impairments 0.07%, 6.78%, and 21.01% in the control, with 0.01% DMS, and with 0.05% DMS, respectively, which gives us reason to state that mutagen significantly influences the meiotic processes. Similar results were obtained for the effect of dimethylsulfate on the other three homozygous forms.Conclusions. From studying chromosome behavior in meiosis of M1 sunflower treated with 0.01% and 0.05% DMS, we can conclude that the effect of mutagen is significant in comparison with the control, as the percentage of impaired cells was high as compared to the control, as evidenced by statistical processing of the data. All phases of meiosis in PMC, from start to completion, can be simultaneously observed in anthers of flowers of a single calathidium.

493 Inducing Polyploidy Pollen in Apple Cultivars

To perform apple polyploid breeding the ways of inducing polyploidy pollen with temperature and chemicals were studied. Materials include 13 diploid cultivars: Red Chief, Dai Hong, Rose Red, Golden Delicious, Mollie's Delicious, Gala, Bella, Jonathan, Fuji, Qiu Kou Hong, and Yan Qing, OBIR-2T-47. Chemicals: Chloroform, N-nitroso-ethylurea. At the beginning of PMC meiosis, fruiting branching groups were covered with plastic bags to raise temperature or were treated with chemical. After covering, temperature during the day increased 2 °C, generally not lower than 0 °C. Whether branches received high temperature or chemicals treatment, polyploidy pollen was induced to produce. The pollen grain of CK is tricolporat, its polar view is triangular, and its diameter almost 40 μm, showing no difference in size. Rate of empty pollen grain is low. Pollen grains that were treated were different in size, and rate of empty pollen is high, part of pollen grains germinating colporat change into tetracolporat with a few polycolporat, its polar view is square, round, and oval. The diameter of large pollen grains was 45-48 μm, increased by 11-12%. Giant pollen grain are 50-68 μm, increased by 25%-70%. Rate of induction is different in different cultivars. For most cultivars, giant pollen grain is 0.3%-0.5%. Gala and OBIR-2T-47 were higher, reaching 2.5%-7%. Chemicals caused damage on cultivars. Delicious strains were easily damaged.

Cytogenetic relationship ofAegilops longissima chromosomes with common wheat chromosomes

The relationships of three wheat-Aegilops longissima chromosome addition lines A, C, and D with homoeologous wheat chromosomes were studied in PMC meiosis. Substitutions of alien chromosome A for wheat chromosome 6 B, chromosome C for 1 B and chromosome D for 4 B were obtained. The production of 4 BS/C and 7 BS/D chromosome translocations indicated cytogenetic relationships of C partially to homoeologous wheat chromosomes of group 1 and 4, and D partially to homoeologous wheat chromosomes of group 4 and 7.

Meiosis in a Double Ditelosomic Plant of Pearl Millet

SUMMARYMeiosis in a double-ditelosomic plant of Pearl Millet with 2n=12+4 telocentric chromosome was studied at PMC meiosis. The telocentric chromosomes were found to be corresponding to the 5th chromosome of the normal complement and were designated as 5L and 5S. The mode of transmission of these telocentrics was studied through reciprocal crosses. Origin of the double-ditelosomic condition and the possible use of these telocentrics in chromosome mapping were discussed.

The genomes of Arachis hypogaea. 1. Cytogenetic studies of putative genome donors

Cytological studies of wild diploid Arachis species in the same section of the genus (sect. Arachis) as the cultivated peanut A. hypogaea L. show, with one exception, a karyotype characterized by the presence of 9 pairs of larger chromosomes and one pair of small (‘A’) chromosomes. The exceptional species A. batozocoiKrap. et Greg. has a more uniform karyotype. Interspecific hybrids between diploid species of similar karyotype have moderate to high pollen stainability, those involving A. batizocoi have zero pollen stainability and a very irregular PMC meiosis. Such infertile hybrids are the most likely to produce fertile, stable amphidiploids on doubling the chromosome complement. It is suggested that the cultivated peanut could have originated from such a sterile interspecific hybrid and on morphological and phytogeographic grounds the most likely genome donors are A. cardenasii (nomen nudum) and A. batizocoi of the species within section Arachis, which have been collected up to the present time.

Meiosis in diploid and tetraploid desynaptics of pearl millet

In the progeny of desynaptic diploids, one desynaptic tetroploid is obtained. A comparative study of the PMC meiosis in the desynaptic diploids and the desynaptic tetraploid is carried out. The desynaptic tetraploid is characterised by high univalent and low multivalent frequency. The mean chiasma frequency in the desynaptic tetraploid is only slightly higher than that in normal diploid plants and nearly twice the maximum frequency observed for the desynaptic diploids. Different possibilities for the origin of the desynaptic tetraploid and its genetic constitution are discussed.

Genetically controlled chromosome numerical mosaicism in pearl millet

In the selfed progeny of a diploid plant ofPennisetum typhoides (Burm) S and H, which was a translocation heterozygote and with chromosome number 2n=13+2 telocentrics, one triploid plant was obtained. In the open pollinated progeny of this triploid, one plant with chromosome numerical mosaicism, chromosome number varying from 2n=28 to 37 of which 23 to 33 normal chromosomes and 3 to 7 telocentrics, was obtained. In PMC meiosis higher associations of 5, 6, 7 or 8 normal chromosomes were observed. This plant was highly sterile. Of the five progeny plants that could be obtained on selfing and open pollination 4 plants showed chromosome numerical mosaicism and one plant had a constant chromosome number of 2n=26+4 telos. As this phenomenon of intraplant chromosome numerical variation can be transmitted from generation to generation it was considered to be genotypically controlled. It was further argued that gene combinations are responsible for the instability and not always associated with higher gene dosage and hence higher polyploidy as suggested by Gildenhuys and Brix in induced amphiploids of Pennisetum. The same factor that was responsible for the chromosome numerical mosaicism seemed to be responsible for the origin of the tetraploid from the triploid.

KARYOSYSTEMATIC NOTES ON THE GALIUM PALUSTRE‐GROUP (RUBIACEAE)

SummaryThe European — North African — West Asiatic Galium palustre‐group is a polyploid complex. The aberrant basic chromosome number x=12 was confirmed for the group, and further diploid (2x), tetraploid (4x), octoploid (8x) and (for the first time) dodecaploid (12x) populations were found. In polyploids uni‐ and multivalents are fairly common in PMC meiosis, and average chromosome size decreases with increasing ploidy level. Chromosome number and size of grains PMCs and pollen grains are correlated.Morphological similarities of 2x and 4x within G. palustre, and of 8x and 12x within G. elongatum suggest ± autopolyploid origin of these cytotypes and militate against their taxonomic recognition. On the other hand, morphological and ecological differences back separation of the predominantly temperate‐boreal G. palustre (2x, 4x), the mediterranean‐atlantic G. debile (2x) and the temperate‐mediterranean G. elongatum (8x, 12x), and the allopolyploid origin of the latter.

A Cytological Study onHelianthus NuttalliiT. and G.

SUMMARYThe cytological investigation carried out on Helianthus nuttallii T. and G. showed that, as a rule, the meiosis in PMC proceeds normally. The frequency of disturbances recorded did not correlate with the degree of pollen viability and seed fertility.The karyotype of the species studied is characterized by four types of chromosomes: (A) two pairs with satellites; (B) seven pairs with medial to submedial centromere position; (C) five pairs with submedial centromeres, and (D) three pairs with subterminal centromeres. The chromosomes within the individual groups are very similar to each other wihch makes difficult their identification.

Cytosystematik, bimodale Chromosomens�tze und permanente Anorthoploidie beiOnosma (Boraginaceae)

This study is concerned with the karyology ofOnosma, and partly with related morphological and taxonomical problems. 24 species and subspecies, and l new hybrid have been considered. New or corrected chromosome numbers as well as new combinations and emendations are shown on the table p. 229. Some species have large (L-) and small (K-) chromosomes, some, additional B-chromosomes. Aberrant pairing in PMC meiosis is indicated by Roman numbers.

CYTOGENETICAL STUDIES OF F<sub>1</sub> HYBRIDS RAISED FROM TS BACK CROSSED WITH <i>SECALE CEREALE</i> AND <i>TRITICUM TURGIDUM</i>

External characteristics, somatic chromosome numbers and meiosis in PMC's of backcrossed F1 hybrids raised from amphidiploid TS (Triticum turgidum×Secale cereale)×S. cereale (TSRF1) and TS×T. turgidum (TsturF1) were described in details (Table 1).In four out of five plants of back-crossed F1, TS×S. cereale was 2n=28 (Fig. 1). The number 28 corresponds exactly to the sum of the gametic number of the parental plants, i.e., TS (T. turgidum, n=14+S. cereale, n=7)+S. cereale (n=7)=28. A plant, TSRF1 -50-9, was 2n=27 and another one, TsturF1, was 2n=40 (Fig. 23), in the latter 5 chromosomes being in excess of the expected number 2n=35, i.e., TS (n=21)+T. turgidum (n=14)=35. It is suggested that of 40 chromosomes 14 have been derived from T. turgidum and the remaining 26 might have resulted from duplications of 5 chromosomes in the mother plant TS.All five TSRF1 plants obtained were studied cytologically. Number of bivalents at MI in PMC's were 4-8 in F1-48-1, 4-9 in F1-48-7 and F1-50-7, 7-14 in F1-50-6, and 4-10 in F1-50-9 (Figs. 15-22). Four plants gave the mode at 7II; and the remaining one, F1-50-6, at 10II. The average number of bivalents per PMC was 6.14 and 7.25 respectively in the two categories mentioned above (Table 3). The bivalents were consisted of two elements of equal size, and their form was ring- or stick-shaped. In addition to bivalents V-shaped trivalents were observed very rarely; only 3 cases in 1720 PMC's.Of 8-9 bivalents observed in three plants, TSRF1 -48-1, -48-7, and -50-7, four may be due to pairing between the chromosomes of A and B genomes of T. turgidum, and the remaining 4-5 to the pairing between the chromosomes of R genomes brought together one from TS and the other from S. cereale. Taking in account the cytological surveys on hybrids between T. turgidum and S. cereale (Liljefors 1936; Nakajima 1950, 1952a, b), seven of 14 bivalents in TSRF1-50-6 might have resulted from pairing between the chromosomes of R genomes come from TS and S. cereale, and the remaining 7 bivalents from pairing between the chromosomes of A and B genomes from T. turgidum. The genome constitution of TS (2n=42) might be of AABBRR=42 in the light of present observation on the meiosis in PMC's in TS×S. cereale.In TsturF1, PMCs in an anther were very few, the meiosis was highly abnormal, and normal bivalents were very rare (Figs. 24-26). A gigantic PMC (n=ca. 300) caused by the repeated nuclear divisions without cell division, was observed (Fig. 29).

Título en español.

Se indujo un notable mejoramiento en la inflorescencia de 11 accesiones de Digitaria valida Stent, prolongándose el fotoperíodo a 16 horas diarias aproximadamente. Dos de las accesiones, dcsignadas como 1950C y 1953A, registraron el mayor mejoramiento en el proceso reproductivo bajo estas condiciones. Ambas accesiones produjeron alguna semilla viable, y a pesar de que no germinaron bien se obtuvo progenie de ambas. Ambas progenies produjeron formas aberrantes del tipo materno. Es obvio que hubo una recombinación genética, aunque no se sabe con certeza si esta se debió a cruzamiento o a automixis. Estudios citológicos revelan un alto porcentaje de polen teñible y una meiosis regular en CMP del material paterno. La accesión 1950C posee cromosomas adicionales, aparentemente accesorios, con pocos efectos genéticos. Un análisis del desarrollo del saco embriónico reveló que el saco era normal en cerca de la mitad de los casos y que hubo una supresión del saco apomíctico en otros. Se concluye que las accesiones 1950C y 1953A pueden usarse en experimentos de cruzamiento.

A TEMPERATURE‐SENSITIVE MALE‐STERILE MUTANT OF THE TOMATO

Variable male sterility was encountered in a spontaneous mutant of Lycopersicon esculentum Mill. ‘San Marzano.‘ The trait, conditioned by a single recessive gene vms, was proved by trisomic and linkage tests to lie on chromosome 8, probably in the longer arm between the markers bu and dl. Under field conditions, from June to October in the interior valleys of California, vms develops severely reduced, deformed stamens and defective corolla, being otherwise physiologically and morphologically normal. Despite the production of a limited amount of stainable pollen under these conditions, it is effectively male‐sterile. Earlier in the season in the field and throughout the entire year under normal greenhouse conditions, the flowers are normal except for a slight reduction in the width of corolla segments. Differences in temperature account for the varied response of vms to the environment, minimal temperatures of 30 C in the field and of 32 C in the greenhouse being required to evoke the sterile phenotype. Application of high temperatures to a single branch of vms elicits a response only in the subsequently developed flowers of that branch. The approximate minimal requirements for the greenhouse environment are temperatures of 35 C or higher applied (1) for 4 hr/day for 2 weeks, (2) for 8 hr/day for 1 week, or (3) continuously for 48 hr. The vms response was also elicited by 29.5 C applied continuously for 96 hr and by 40.5 C for 12 hr. Depending upon the rate of growth, the response first appears 3–5 weeks after the start of treatment and continues for approximately the same length of time as that of the treatment. In the light of these findings and of the observed rate of development under the same environment, the sensitive stage is estimated to be flower primordia of 0.075 mm or smaller diam. Buds of this size appear very close to the shoot meristem, are still highly mitotic, and precede meiosis in PMC by at least 10 days—a relationship that is in keeping with the deformity observed in anthers of all dissectable sizes.

Radiation induced asynaptic mutations in durum wheat (Triticum durum DESF.)

The cytological behaviour and the inheritance of two asynaptic mutations independently obtained by neutron treatment of durum wheat seeds of var. Cappelli and Aziziah are considered. Mutant individuals of both lines have normal morphology, but are completely sterile. Analysis of chromosome behaviour at the several stages of PMC meiosis has been thoroughly accomplished in mutant progenies of both varieties during two subsequent generations. A completely random chromosome disjunction was found at anaphase I, together with multipolar spindles, laggard chromosomes etc. At meiotic second division a large amount of abnormalities were found, as a consequence of previous asynapsis and irregular polarization. Some differences in cytological behaviour were found between the asynaptic mutants of Cappelli and the asynaptics of Aziziah. - Genetic analysis demonstrated that both mutations behave as monogenic recessives.

The Chromosomes of Chironja

Like most Citrus species and varieties, the Puerto Rican chironja has nine pairs of short chromosomes. Although micronuclei are formed sporadically, generally the PMC meiosis is normal, and the pollen looks fertile. The chromosome relations do not help us to decide whether the chironja is a hybrid between orange and grapefruit or not.

花粉に及ぼす放射線の影響 I.生殖核の分裂に及ぼすγ線の影響について

The effects of pollen grain irradiation on pollen-tube mitosis were investigated. The data were obtained from artificial culture. For irradiation gamma-rays were applied with 137Cs 6, 000c at a dose rate 55kr/hr. The doses ranged from 0.5 to 100kr.1) Inhibition of mitosis increased with increasing dose; namely the higher the dose, the more reduced was the frequency of nuclear division and the more delayed was the time of its occurrence.2) In Lilium auratum the generative nucleus remained mostly undivided in showing chromosome elements even at 5kr, while at 20kr a few nuclei consisted of chromatin masses or chromosomes. The pollen-tubes of Lilium did not grow smoothly on the media. In natural condition, therefore, their pollen-tube mitosis may be more radio-resistant.3) At 80kr irradiation of Camellia japonica pollen the mitotic division of the generative nucleus was almost completely inhibited.4) In Camellia sasanqua the generative nucleus did not divide into 2 sperm nuclei above 25kr, while relatively many generative nuclei with chromosomes were observed at 50kr.5) The pollen grains of Impatiens balsamina had the highest radio-resistance. At 50-80kr the generative nucleus underwent complete mitotic division.6) Radio-sensitivity of pollen grains varied widely according to the species. In general, their pollen-tube mitosis was much more radio-resistant than the meiosis in PMC's and mitosis in root tips.

Karyogenetical Studies on the Intergeneric F<sub>1</sub> Hybrids Raised between <i>Triticum turgidum</i> and <i>Haynaldia hordeacea</i>

1. In the present research, karyogenetical studies on the F1plant raised from T. turgidum (n=14)×H. hordeacea (n=7) were carried out.2. In general, the external characteristics of the F1 plant resembled the parents, but very closely resembled H. hordeacea, the pollen plant (Figs. 12).3. The somatic number of chromosomes of the F1 plant was 28. This number has 7 in excess to the usual number which corresponds to the sum of the gametic numbers of both parents, viz., 14+7=21. The surplus 7 chromosomes may have been derived from duplication of the 7 chromosomes of H. hordeacea, the pollen plant.4. At the heterotypic metaphase in meiosis of PMC's of the F1 plant, 512 bivalents or 418 univalents were observed (Table 4). 6 or 7 of the 12 bivalents might have been formed by the autosyndesis among the chromosomes of H. hordeacea, and the remaining 5 or 6 bivalents probably were made by autosyndesis between the chromosomes of AB genomes of T. turgidum.5. The F1 plant shows to be completely sterile in natural selfing, however, it is perennial.

Cytogenetical studies on intergeneric hybrids between <i>Haynaldia</i> and <i>Secale</i>

1. In the present reserach, the external characteristics and the meiosis in PMC's of F1 plants raised between Secale fragile (n=7) and Haynaldia villosa (n=7) were studied. To study meiosis 11 individuals out of 25F1 plants were empolyed.2. The percentage of matured F1 to the number of pollinated florets was 8.26%. This value is rather high as the percentage of F1 for the pollinated florets in the hybridization between H. villiosa and S. cereale.3. Generally speaking, the F1 plants possess external characteristics of both parents and they are almost intermediate between the parents (Fig. 1 and Table 1).4. The number of somamtic chromosomes in the root tip cells of the F1 plants was ascertained to be 14, and this number exactly corresponds to the sum of the gametic number of the parents, viz., 7+7=14. In the meiosis of PMC's the same number of chromosomes was also observed in the root tip cells.5. At the heterotypic metaphase in PMC's of F1 hybrids, 0-3 bivalents were observed. Their frequency is shown in Table 2, and their lack appears to be the mode. A ring-shaped bivalent and a heteromorphic stick-shaped bivalent were observed rarely, while oridinary stick- shaped bivalents formed by two equal sized elements conjugated end to end losely were usualy observed (Table 2). These bivalents seem to be derived from autosyndesis between chromosomes of V genome of H. villosa and the chromosomes of S. fragile respectively. Considering the foregoing, there seems to be no homology between V genome of H. villosa and that of S. fragile, syndesis will not occure between their chromosomes. Trivalents addition to bivalents were observed, but no tetravalent was observed. At heterotypic ana-telophase of PMC's the chromosomes were distributed to the opposite poles in the ratio 7:7-0:14 (Table 3).6. At the heterotypic metaphase in meiosis, univalents were normally scattered in spindle, but the formation of equatorial plate and the longitudinal splitting of all the univalents were rarely observed and consequently these processes gave rise to the formation of non-conjugation or restitution nucleus.7. In the tetrad stage, PMC's consisting of 1-6 cells were observed, with the 4 cell tetrad showing the highest parcentage (82%).8. Most of F1 plants show parcial fertility by natural selfing, though the percentage of fertility was not high (Table 5) and some grains were obtained.

Cytogenetical studies of triple hybrid from F1 Triticum turgidum× Secale cereale and Triticum vulgare

1. The meiosis of PMC's of 35 individuals of F2 raised between two species of Triticum and Secale cereale is described.2. The number of bivalents observed in one PMC is 11-23 at the heterotypic metaphase of Triticum-Secale triple F2 plants, and the frequency of those bivalents is shown in Table 1. And the mode of the number of bivalents was 14II in the individuals having 2n=28-32 chromosomes, 15II in those of 2n=33-37, 15II-19II in those of 2n=38-44 and 17II-21II in those of 2n=45-50. Generally, the number of bivalents increases as the number of chromosomes increases; showing that the number of homologous chromosomes will also increase when the number of chromosomes increases.3. Trivalents or tetravalents, suggesting that the plants have 3 or 4 homologous chromosomes.4. Triticum-Secale triple hybrids employed in the present research are of the 2nd generation raised from the hybridization between two species of Triticum and Secale cereale each of which has quite different nature. Therefore, the meiosis in PMC's is very anomalous.