Showing papers on "Microspore published in 1977"
TL;DR: Rice anthers containing microspores in the early-uninucleate to first-mitosis stages were induced successfully to develop into plants in vitro through an intermediary step of callus formation to account for the occurrence of the diploid and polyploid plants.
Abstract: Rice (Oryza sativa L, 2n=24) anthers containing microspores in the early-uninucleate to first-mitosis stages were induced successfully to develop into plants in vitro through an intermediary step of callus formation Callus initiation occurred with highest frequency in anthers containing mid-uninucleate imcrospores The callus derived from different stages of microspore development differed in the potential to differentiate into plants The plants regenerated from pollen callus were predominantly haploid or diploid; polyploid and aneuploid plants were relatively infrequent The first division of the uninucleate microspores was asymmetrical, resulting in the formation of large vegetative and small generative nuclei The vegetative nucleus divided repeatedly and assumed the major role in the formation of callus, whereas the generative nucleus degenerated rapidly Simultaneous division of the two nuclei was observed in a few pollen grains Nuclear fusion during the very initial stages of pollen development was postulated to account for the occurrence of the diploid and polyploid plants
49 citations
TL;DR: It was possible to obtain green plantlets from microspores isolated from precultured anthers of Nicotiana tabacum and Hyoscyamus niger without using a cold treatment and the suggestion that glutamine plays an important role in the development of androgenetic embryos ofNicotiana was suggested.
47 citations
TL;DR: In this article, a mixture of haploid, diploid and polyploid cells were used to induce callus formation in barley spikes. But the conditions or the large scale production of green plants from these calluses remain to be identified.
36 citations
TL;DR: The shedding of grains in the microspore stage suggests that microgametophyte evolution had passed the stage of prothallial cell production, and that Lasiostrobus is an advanced member of the Paleozoic gymnosperm complex.
19 citations
TL;DR: Microsporogenesis was studied in the male-female sterile F2 segregants of a safflower cross involving 'US-10' and '57-147' cuitivars and was compared with normal meiosis in the F1 hybrids.
Abstract: Microsporogenesis was studied in the male-female sterile F2 segregants of a safflower cross involving 'US-10' and '57-147' cuitivars and was compared with normal meiosis in the F1 hybrids. In the microspores of the sterile plants contraction of chromosomes during prophase was irregular and patchy and they did not stain well with acetocarmine. At MI, most of the 24 chromosomes tended to stick to each other at random resulting in the formation of several chromosome bridges during AI. Multipolar meiotic divisions were observed. The second division was rarely seen. Apparently, meiosis ends with a multipolar AI separation and with the formation of 3- to 9-celled "quartets" which later develop nonfunctional pollen grains. The onset of meiosis in sterile plants was delayed and microsporogenesis subsequently progressed at a much slower rate than in fertile F1 hybrids. Three interacting nuclear genes appear to cause male-female sterility and affect microsporogenesis by interfering with some component essential for...
18 citations
TL;DR: In microspores containing globular embryoids 0, 1 or 2 nuclei derived from the generative nucleus could be recognised; these, however, contributed few if any viable cells to the developing plantlets.
Abstract: Cultured anthers of Nicotiana sylvestris produced 70% haploid, 14% diploid, 8% triploid, 2% tetraploid and 6% mixaploid plantlets. Immediately pre-mitotic anthers produced no plantlets; mitotic and immediately post-mitotic ones did so. Stage of anther development at initiation of culture was not related to production of non-haploids. Embryoids arose from divisions of the vegetative nucleus. In microspores containing globular embryoids 0, 1 or 2 nuclei derived from the generative nucleus could be recognised; these, however, contributed few if any viable cells to the developing plantlets. Metaphase plates with higher than the haploid number of chromosomes were seen and probably arose through nuclear fusion at an early stage.
18 citations
TL;DR: An important part of the polyploidy in the tissues in the consequence of endomitosis in the microspore nuclei is seen in older calli but some tissues remain haploid.
Abstract: SUMMARYAnthers of barley have been cultivated at the uninucleate stage on several artificial media and the evolution of the microspores has been followed during the first days. The presence of an auxin is necessary for the cell proliferation and several pretreatments increased the frequency and the precocity of the divisions: the best is a storage of two days at 3°C before inoculation. An important part of the polyploidy in the tissues in the consequence of endomitosis in the microspore nuclei. The proportion of polyploidy rises in older calli but some tissues remain haploid.
16 citations
TL;DR: In studies with Lycopersicum peruvianum, cytophotometric determinations of the DNA content in the isolated nuclei from calli of in vitro anther cultures of the genotypes S 1 S 3 and S 12 S 13 were carried and indicated that the calli produced from another cultures can differ in type.
15 citations
TL;DR: Mature anthers of some plants of Narcissus biflorusCuri, cultivated under subtropical conditions at Jammu, were found to contain monads, microspore mother cell embryo sacs, and multinucleate ‘embryoids’.
Abstract: Mature anthers of some plants of Narcissus biflorus
Curi, cultivated under subtropical conditions at Jammu, were found to contain monads, microspore mother cell embryo sacs, and multinucleate ‘embryoids’ In addition, multicellular ‘embryoids’ resembling those obtained in vitro through anther culture were also observed All these structures arise from the microspore mother cells which do not follow regular course of microsporogenesis
12 citations
TL;DR: The embryological evidence points to a closer affinity of Bauera Banks ex Andr.
Abstract: In Bauera capitata Ser. ex DC. the anthers are tetrasporangiate with a three- or four-layered anther wall. The tapetum is glandular and its cells remain uninucleate. Tannin accumulates in the epidermis and the endothecium, and many connective cells in addition contain druses. Simultaneous cytokinesis leads to tetrahedral and isobilateral tetrads of microspores. The pollen is shed when two-nucleate and is gorged with starch. Degeneration of contents of one or more sporangia is frequent. The ovules are anatropous, crassinucellar and bitegmic. Twin microspore tetrads and twin embryo sacs are common but only one embryo sac reaches maturity. The development of the embryo sac follows the monosporic, Polygonum type. Starch accumulates in the mature embryo sac and remains until the initiation of endosperm. The antipodal cells persist until fertilization and rarely multiply. The seeds are frequently sterile but contain a well-formed outer integument. The healthy seeds have in addition a five- or six-layered inner integument, a nuclear type of endosperm and an embryo. The embryological evidence points to a closer affinity of Bauera Banks ex Andr. to the Cunoniaceae than to the Saxifragaceae.
11 citations
TL;DR: Synaptonemal-like complexes appear in Allium cepa microspores as tubular structures formed of 60 nm large granules which show a finely fibrillar texture.
Abstract: Synaptonemal-like complexes appear inAllium cepa microspores as tubular structures. They are formed of 60 nm large granules which show a finely fibrillar texture. The multiple exposure rotation technique byMarkhamet al. suggests that these tubular structures are composed of twelve subunits.
TL;DR: In some anthers, the behaviour of microspores deviates from normal course and the microspore increases in size and the nucleus undergoes 3 successive divisions giving rise to an 8-nucleate structure which resembles organized Polygonum type of female gametophyte.
Abstract: SUMMARYIn Heuchera micrantha the anthers are tetrasporangiate and cytokinesis is of simultaneous type. In the majority of the tetrads microspores soon separate from one another but in a few they remain intact. Tetrads with two degenerating and two multinucleate microspores are often observed. In a few tetrads cell walls undergo lysis resulting in a large, spherical 4-nucleate structures. In some anthers, the behaviour of microspores deviates from normal course: (i) Instead of developing into normal pollen grains, the microspores enlarge, their cytoplasm becomes vacuolated and finally they degenerate, (ii) The microspore increases in size and the nucleus undergoes 3 successive divisions giving rise to an 8-nucleate structure. Three nuclei at each pole organize into cells while the remaining 2 lie in the centre. Such elongated microspores resemble organized Polygonum type of female gametophyte. (iii) Spherical, 4- and 8-nucleate microspores showing cruciate arrangement of nuclei are often met with. Disposit...
TL;DR: Histological and histochemical examinations of sodium 2,3-dichloroisobutyrate treated tomato floral buds showed that I)CB affected the development of microspores and tapetal cells, and the interference of carbohydrate metabolism by DCB was indicated.
Abstract: Histological and histochemical examinations of sodium 2,3-dichloroisobutyrate (DCB) treated tomato floral buds at various stages of development showed that I)CB affected the development of microspores and tapetal cells. DCB at 0-075 and 0-15% resulted in the formation of uninucleate microspores, absence of microspore starch, retardation of exine formation, degeneration of microspore cytoplasm, and a delay in the breakdown of the tapetum. Embryo sac development was unaffected by DCB. The interference of carbohydrate metabolism by DCB was indicated. Reduction of fruit set by DCB was caused by abnormal or lack of pollen formation.
1 Jan 1977
TL;DR: In this paper, histological and histochemical examinations of tomato floral buds at various stages of development showed that I)CB affected the development of microspores and tapetal cells.
Abstract: Histological and histochemical examinations of sodium 2,3-dichloroisobutyrate (DCB) treated tomato floral buds at various stages of development showed that I)CB affected the development of microspores and tapetal cells. DCB at 0-075 and 0-15% resulted in the formation of uninucleate microspores, absence of microspore starch, retardation of exine formation, degeneration of microspore cytoplasm, and a delay in the breakdown of the tapetum. Embryo sac development was unaffected by DCB. The interference of carbohydrate metabolism by DCB was indicated. Reduction of fruit set by DCB was caused by abnormal or lack of pollen formation.
TL;DR: Differentiated chromosome segments were observed during studies of pollen mother cells of A. cepa during the first meiotic division and it is suggested that they correspond to the secondary constrictions seen under the optical microscope.
Abstract: Differentiated chromosome segments were observed during studies of pollen mother cells of A. cepa during the first meiotic division. Their structure is like those of the nucleolar organizing region (NOR) described in A. cepa microspores. It is suggested that these differentiated chromosome segments correspond to the secondary constrictions seen under the optical microscope.