Anther Tissues Research Articles

CYTOGENETICS OF FLOWER MODIFICATION OF A CYTOPLASMIC MALE-STERILE TOBACCO

Plants combining the cytoplasm of Nicotiana debneyi and the 48 chromosomes from N. tabacum are male sterile. Early backcross generations of the amphidiploid hybrid to male N. tabacum produced a great variety of plants from which a series of phenotypes with characteristic flower forms and transmission rates have been isolated. Type 1A possesses completely feminized stamens and deeply split corollas, breeds true when backcrossed to normal males and carries 48 N. tabacum chromosomes. Other phenotypes, 2C, 3E and 4H, range toward normal morphology of corollas and stamens. Like 1A, 2C forms no anther tissue and has 48 chromosomes. This type is transmitted to 36.3% of the backcross progeny, the remainder being of type 1A; presumably 2C carries a chromosome segment from N. debneyi that is responsible for the partial restoration of flower structure. In contrast, both 3E and 4H produce anthers and possess an extra chromosome. The extra chromosomes are transmitted to only 19.9% and 7.1% of the progeny, respectively. Significantly, the extra chromosomes found in the anther-forming types are nucleolus organizing and carry a satellite from N. debneyi. On the basis of these observations, we surmise that differentiation of anthers in plants with N. debneyi cytoplasm may depend on the presence of a nucleolus-organizing chromosome from that species. This chromosome is unstable; unaltered, it conditions a highly restored phenotype (4H), but when structurally modified, it may control different phenotypic expressions. Other examples of satellited restorer chromosomes had been reported for different cytoplasmically male-sterile combinations; therefore, the phenomenon may have more general significance.

Aspects infrastructuraux des altérations des anthères de Silene dioica parasitées par Ustilago violacea

The structural characteristics of the sporogenous and parietal tissues of healthy anthers of Silene dioica (L.) Clairv. (Caryophyllaceae) are described as well as those of anthers infected by Ustilago violacea (Pers.) Rouss. (Ustilaginales). In infected anthers, the invading dikaryotic mycelium grew intercellularly and very rarely penetrated the cells. The pathogen stopped stamen histogenesis at an early stage, causing necrosis specifically of the sporogenous tissue either directly or following hypertrophy. Five stages were distinguished during the histological modifications leading to anther destruction. (1) First, the mycelium developed in the anther filament and spread throughout the superficial tissues of the anther without causing histological changes in the anther. (2) Then, some sporogenous cells began to show necrosis and formed compact masses. (3) An increasing number of sporogenous cells became necrotic following strong vacuolisation and hypertrophy. (4) Hyphae grew profusely in the necrotic mass of sporogenic cells. (5) Finally, the fungus produced teliospores which filled the sporangial cavity.

THE CYTOLOGY OF POLLEN ABORTION IN S CYTOPLASMIC MALE‐STERILE CORN ANTHERS

The anther development of the S male‐sterile cytoplasm and the fertile maintainer (N) cytoplasm versions of corn inbred W182BN and the restored S cytoplasm version of inbred NY821LERf was studied by light and electron microscopy and compared to pollen abortion in the C and T types of male‐sterile cytoplasms. The S anthers did not deviate from the non‐male sterile (N) anthers until a very late stage of pollen development. Tapetal cells developed and disappeared normally in the S version which differentiates this cytoplasm from the C and T types. Although some modified membranous structures were seen in a higher frequency in the large vacuole of the sterile S pollen than in the N and restored S counterparts, the mitochondria and other organelles in the S pollen appeared normal up to the time of pollen abortion. Pollen abortion in the S cytoplasm did not occur until the developing pollen was nearly mature. At this time the pollen grains disintegrated abruptly but other anther tissues appeared unaltered. The male sterility of S plants appeared to be determined by the pollen itself without external influence from the tapetum.

The Cytology of Pollen Abortion in S Cytoplasmic Male-Sterile Corn Anthers

The anther development of the S male-sterile cytoplasm and the fertile maintainer (N) cytoplasm versions of corn inbred W182BN and the restored S cytoplasm version of inbred NY821LERf was studied by light and electron microscopy and compared to pollen abortion in the C and T types of male-sterile cytoplasms. The S anthers did not deviate from the non-male sterile (N) anthers until a very late stage of pollen development. Tapetal cells developed and disappeared normally in the S version which differentiates this cytoplasm from the C and T types. Although some modified membranous structures were seen in a higher frequency in the large vacuole of the sterile S pollen than in the N and restored S counterparts, the mitochondria and other organelles in the S pollen appeared normal up to the time of pollen abortion. Pollen abortion in the S cytoplasm did not occur until the developing pollen was nearly mature. At this time the pollen grains disintegrated abruptly but other anther tissues appeared unaltered. The male sterility of S plants appeared to be determined by the pollen itself without external influence from the tapetum.

Studies on isoenzymes of anther tissue of fertile and cytoplasmic male sterile wheat plants

We studied the isoenzyme pattern of peroxidase, esterase, malate dehydrogenase and leucine aminopeptidase from anther tissue of fertile and male sterile wheat plants by means of polyacrylamide gel electrophoresis.Three of the tested enzymes (peroxidase, esterase and leucine aminopeptidase) show differences in their isoenzyme pattern.The pattern of proteins extracted from sterile anthers lacks isoenzymes present in the extracts of fertile anthers.The differences in enzyme activity of fertile and sterile plants seem to be a consequence rather than a primary cause of cytoplasmic male sterility.

Cyto-histological studies on anther and pollen development in alloplasmic rye.

Alloplasmic plants of rye, Secale cereale L., with cytoplasm of Triticum durum Desf. are studied in order to investigate the causes of male sterility. Meiosis can be considered as normal because the alterations found had little entity. Abortion of pollen was progressive during microspore maturation; however, the variation among plants in percentage of aborted pollen was high (from 10%. to 98%.), being the average 29.3%. Histological observations showed that the only alteration in anther wall tissues was the non total disappearance of tapetum. So, the fusion of neighbouring loculi and the subsequent dehiscence of the anther was impeded. Therefore, the male sterility in this alloplasmic rye is a case of functional male sterility because the pollen being partially fertile cannot intervene in fertilization by the indehiscence of the anthers. The independence between pollen abortion and tapetum perdurability is discussed. Other events as pistilloidy are described.All studies were made simultaneously with the normal rye counterpart as control.

Uridine diphosphate glucose:fatty acid glucosyl transferase activity of rape ( Brassica napus L.) anther tissue

Particulate fractions from mature rape anther tissue catalysed the incorporation of glucose from UDPglucose into endogenous lipids. The UDPglucose:fatty acid glucosyl transferase was tightly bound to particulates that could be suspended in 0.1% Triton X-100. The apparent K m for UDPglucose was 3.5 · 10 −6 M. In Tris buffer the enzyme has a pH optimum of 8.0 and a temperature optimum of 30°C. In the presence of NaF, the transferase activity was proportional to protein concentration, time, and other variables of the reaction mixture. ADPglucose, GDPglucose, and CDPglucose did not compete with the activity of the UDPglucose-dependent glucosyl transferase. Gas chromatographic and high performance liquid chromatographic analyses indicated that the endogenous fatty acids glucosylated in vitro had carbon chain lengths of C 16 to C 20 . This is the first report on the biosynthesis of non-phosphorylated glucosyl esters of fatty acids in higher plants.

Anther and Pollen Abnormalities Induced by Cold Treatment and Their Varietal Differences in Rice Plants

The physio-genetical studies on in rice plants were studied. Three paddy rice cultivars Reimei, Kinmaze and Te-tep were used, the former two of which belong to japonica type, and the latter to indica type. At the meiotic stage of pollen development, treatment (10-15'C, 4 clays) was performed to induce the abnormalities in anthers and pollens of these cultivars. There were distinct varietal differences in seed fertility. Reimei was the most tolerant to the treatment. Close relationship between the seed fertility and the number of dehisced anthers per spikelet was observed, particularly in Kinmaze and Te-tep. Cold injuries such as sterility of pollens, deformance of anther tissue, growth inhibition of anther loculi were observed in all cultivars, although the degrees of these abnormalities varied consiclerably among the cultivars. Anther abnormalities were most frequently observed in Kinmaze. Percent of fertile pollens decreased with the increase of anther abnormalities, particularly in Te-tep. Anatomical observations in injured anthers showed following features : (1) smaller and/ or flattened loculi, (2) tapetal hypertrophv , (3) poor and/or no development of dehiscence -sites, etc. It was concluded from these observations that the occurrence of anther and pollen abnormalities 1were the cause of seed sterility, and the varietal difference in so called cold tolerance in rice plants means the grade of resistance of pollen and anther tissue to the low temperature during the meiotic period of pollen development.

Effects of nuclear restorer genes on the cytochrome content of corn pollen mitochondria

Mitochondria were isolated from mature pollen grains of corn (Zea mays L.) having normal (N) or restored Texas male-sterile (TRf) cytoplasm. Comparison of the cytochrome content of the two sources by low-temperature difference spectroscopy indicates that inbred lines carrying nuclear restorer genes and T cytoplasm have an increased cytochrome oxidase content. A lower cytochrome oxidase concentration was found in mitochondria isolated from anthers of nonrestored Texas (cms-T) male-sterile cytoplasm corn than from those isolated from nonexserted anthers of N or TRf plants. Mitochondria in nonsporogenous tissue of cms-T anthers collected just before the time of anthesis of N plants had fewer well defined cristae than mitochondria in comparable anther tissue of N or TRf plants.

Relationships Between Anther Browning and Plantlet Formation in Anther Culture of Nicotiana tabacum L.

Summary Anthers of Nicotiana tabacum cv. Wisconsin 38 contammg pollen grains in various developmental stages were cultured for 55 days at 23°C to investigate the relationship between the formation of plantlets from pollen and browning of the anther. Browning took place in anthers containing binucleate pollen grains during the first 10 days after inoculation onto Nitsch's basal medium (1969) , whereas it was continuously observed for as long as a month in anthers containing micros pores in the uninucleate stage and in those undergoing pollen mitosis. Plantlet formation in the first instance was observed during the first 3 to 5 weeks of culture and was never detected thereafter. There was no positive correlation between anther browning and plantlet formation. Plantlet induction was delayed for one week, but it was observed to be continuously effective until the cultures were 50 days old in the anthers containing uninucleate and mitotic microspores. The protraction of senescence in anthers appears to be of great importance for the induction of embryogenesis in microspores at this stage of development. There was a positive correlation between the duration of anther browning and the time required for plantlet production. That is, the percentage of plantlet formation in anthers having browned during the first 2 weeks was low, whereas the frequency of plantlet formation was high in long-lived anthers. These results suggest that there is a critical period for the induction of pollen embryogenesis in the early binucleate stage. Most microspores not yet having undergone pollen mitosis can attain to this stage with the nutritional or hormonal aid of living anther tissue; the embryogenesis can never proceed if anther browning has occurred before this stage has been attained. In a more advanced stage the duration of such a situation seems to be shorter.

Endo-polymethylgalacturonase of boll weevil larvae, Anthonomus grandis: An initiator of cotton flower bud abscission

Pectinases of boll weevil larvae were fractionated by gel filtration, (NH4)2SO4 precipitation, and hydroxylapatite chromatography. A fraction rich in endo-polymethylgalacturonase (endo-PMG) was able to macerate anther tissue and initiate abscission when injected into cotton flower buds. By partially destroying the cuticular permeability barrier, ethyl acetate and other solvents enhanced the abscission-initiating ability of the enzyme fraction. Growth regulator imbalances and degradation products resulting from endo-PMG action are probably the ultimate causal agents of abscission in flower buds.

Characterization of the ‘very’ lysine-rich histones of active and quiescent anther tissues of Hippeastrum belladonna

Cytochemical studies demonstrated that developmental stages of anther tissue of Hippeastrum belladonna stained differently after exposure to a competitive mixture of eosin and fast green dyes. Nuclei of active tissues stained fast green positive while those of metabolically inactive tissues were eosinophilic. Differences in the polyacrylamide banding patterns of ‘very’ lysine-rich F1 histones occurred in tissues with varying metabolic states. Heterogeneity in the ‘very’ lysine-rich histones was further observed by gradient elution chromatography on Amberlite IRC-50 with a linear gradient of guanidinium chloride solutions. The ‘very’ lysine-rich histones of inactive tissue (tapetal tissue) were resolved into seven components, and five components were observed in the ‘very’ lysine-rich histones of active tissue (pre-meiotic tissue). Distinct mobilities in polyacrylamide-SDS gels of ‘very’ lysine-rich histones components further substantiated biochemical differences in the F1 histones of active and inactive tissues. Analyses of the ‘very’ lysine-rich components of active and inactive tissues showed that their amino-acid compositions, while very similar, revealed consistent differences. The possible role which histones play in gene regulation and, more specifically, the influence of the ‘very’ lysine-rich histones in cell regulation are discussed in light of these findings.

Premeiotic Mitosis in Maize: Evidence for Pairing of Homologues

SUMMARYThe last premeiotic mitosis was studied in sporogenous tissue of maize anthers. This division is poorly synchronized and of short duration (relative to the premeiotic interphase). In these mitotic cells homologous chromosomes appear closely paired side by side at metaphase. It is not clear whether such association is initiated at the prophase of this division (from a heretofore random distribution), but observable homologous association seems to begin in this material at about mid-prophase and to be maximal at metaphase. It is also visible at anaphase.

Electron-microscopy on anther tissue and pollen of male sterile and fertile wheat (Triticum aestivum L.)

1. Anther tissue and pollen grains of cytoplasmic male sterile and fertile wheat were studied with the aid of an electron-microscope for differences in cytoplasmic structures.

Application of rejection ellipse to breeding cytoplasmic male sterile strain of sugar beets

In view of distinct differences of pH values noticed in anther tissue, especially at pollen tetrad and pollen grain stages, studies have been conducted on the application of rejection ellipse to breeding of complete male sterile strain and determination the various types of male sterility. The rejection ellipses were obtained on the basis of the critical region of bivariate statistics of two developmental stages of pollen. The long axis and short axis of the ellipse correspond to the pollen tetrad and the pollen grain stages respectively. The rejection ellipses of normal and complete male sterile types which are diagrammed at 5% level of significance distinctly separated from each other, while that of semi-sterile type overlapped partially with two above mentioned ellipses. Such rejection ellipses are seemingly useful for breeding of the male sterile strain from a given population.

The rate of consumption of oxygen by anthers of Tradescantia paludosa

The paper describes an adaptation of the Hersch technique for the micro-assay of oxygen which permits one to sample the oxygen content of the gas in a small enclosure containing some forty anthers, and thereby to evaluate the rate of consumption of oxygen by a known mass of anther tissue over a period of several hours and with varying partial pressures of oxygen in the moist chamber. The fall in the rate of consumption of oxygen with partial pressure in the gas phase is best accounted for by assuming that this reflects the limited extent to which the oxygen is able to penetrate the substance of the anther. Calculations based on a simple diffusion model agree only qualitatively with the observations. In part this is due to the fact that even when oxygen is not limiting, respiration declines with the time which has elapsed since the anther was dissected from the bud. Better quantitative agreement is obtained if it is assumed that the surface is much less permeable to oxygen than the bulk of the anther tissue. The oxygen consumed per unit mass was found to be greatest in the small anthers containing microspores in early interphase, falling as the microspores approached the end of interphase, and becoming least during mitosis. The respiration of early interphase anthers was slightly, but possibly not significantly, depressed by the addition of 5 per cent CO 2 to the gas phase. The mean respiration rate of anthers containing microspores in division was not measurably affected by 5 per cent CO 2.

Histochemical studies on the cytoplasmic male-sterility of sugar beets, with special reference to the hydroeenion concentration, carbohydrates and amino acids in anthers.

The present paper is devoted to the observation of histochemical phenomena in anther tissue of cytoplasmic maie-sterile sugar beets contrasted with those in normal strains. I. Hydrogen-ion concentration in anther tissue. Based on several observations using pH indicators (Methyl red or Brom thymol blue), following conclusions could be drawn(Table 1, 2, 3 and Fig. 1, 2, 3). In the early stage of microsporogenesis, the pH values in anther tissue of both rnormal and malesterile types are rather high ranging: from 6.6 to 7.0. As the age of anthers of normal types advances to the microspore stage, the pH values decrease to about 6.2, then they increase agnin to about 6.8 at the D. ollen-grrain stage, and, at the anthesis, the pH values decrease to about 6.2. On the other hand, the pH values observed in anthers of male-sterile types never show such zig-zag curves as those of normal strains during the microsporogenesis, but gradually decrease to about 6.2 at the anthesis.

Histochemical anomalies in anther tissues of rice plant, Oryza sativa L., under artificial low temperature conditions with reference to the intervarietal difference in cold resistance.

Some histochemical observations were made on anther tissues of rice plants treated under artificial low temperature conditions (9-10'C for 24 hours or 17'C for 5 days) in the summers of 1956 and '57, the res;ults of which are reported here. Three improved paddy varieties, viz., Fujisaka No. 5, Towada and Norin No. 16, were used, the first two being known to be cold resistant and the last one susceptible. 1. The histochemical deviation from the normal process occur especially pronouncedly in the three tissues, viz., transitory, pollen, epidermis and parenchyma. 2. During the period from the stage just before the PMC divisian to that of the extine formation, transitory tissue in the affected anther always shows remarkable increase in the content of reducing substances and decrease in that of polysaccharides. 3. In affected tapetum increased peroxidase activity and the content of reducing substances are bbserved during the period from the first to second contracting stage of pollen.

A DICENTRIC WHEAT CHROMOSOME IN DIVISION

A dicentric chromosome was observed in the F2 progeny of an interspecific wheat cross. It is suggested that: the dicentric arose from breakage and fusion of two nonhomologous univalent chromosomes in the preceding meiosis. Because only a few bridges were observed in root tips, anther wall tissue, and in sectioned ovaries, it was concluded that the dicentric persisted in the plant because of parallel separation of the chromatids. Somatic variation was observed in some root tip cells. At meiosis, the dicentric was invariably paired with its two homologues and both centromeres were effective in orientation on the plate. Chains-of-five and even rings-of-five were formed in one spike. In another, the loss of one chromosome arm prevented such associations but several forms of trivalents occurred. In one spike, internal chiasmata were formed in the intercentric region of the chromosome. On the chiasmatype theory of crossing over this should have caused bridges at succeeding stages. Besides the lack of bridges, in some cells at AI there was definite evidence that the dicentric was breaking apart and forming an extra chromosome. To explain this phenomenon it is suggested that the effect of the one centromere was nullified by the other and the full consequences of chromatid breakage and reunion in chiasma formation were not fulfilled.

Changes of the Intracellular Reducing Intensity in the Pollen Mother Cells During Meiosis of the Young <i>Lilium</i> Anthers

1. The total reducing power in various tissues of Lilium anthers, especially of the sporogenous tissue (the sporogenous and the pollen mother cells), was determined by means of the indicator method during the development of the sporogenous tissue.2. The reducing power of the sporogenous and tapetal tissues increases from premeiosis to meiosis remarkably, while in other tissues no such remarkable increase is seen.3. The redox-potentials of N. V. E. Grubler were determined by using Michaelis' vessel with the changes of its colours.