Abortive Ovules Research Articles

Comparison of Methodologies for in Ovulo Embryo Rescue of Seedless Grapes

Abstract In ovulo embryo rescue provides an attractive alternative to conventional methods of breeding for seedless grape (Vitis) by allowing recovery of progeny from abortive ovules of seedless × seedless crosses. This technique theoretically increases the proportion of seedless progeny that can be obtained in one breeding cycle (1). Proper inheritance studies can be accomplished by heretofore impossible direct combinations of seedless cultivars.

The Role of Beetles in the Pollination of Zamia furfuracea L. fil. (Zamiaceae)

The Role of Beetles in the Pollination of Zamia furfuracea L. fil. (Zamiaceae)

REPRODUCTIVE MORPHOLOGY OF QUERCUS (FAGACEAE)

Details of inflorescence, floral, and fruit morphology have been studied in more than 120 species of Asiatic and American Quercus. Of the two subgenera, subgenus Cyclobalanopsis has fewer species but greater diversity of reproductive morphology than subgenus Quercus. Some character states of subgenus Cyclobalanopsis, such as more numerous stamens, male flowers sometimes grouped in dichasia, abortive ovules well developed, prominent intrusive septae in the nut, and lamellate cupules, are shared with Lithocarpus. The diversity of cupular sizes, coverage, and ornamentation raises questions about the adaptive nature, ecological function, and phylogeny of the cupule, which clearly has by now evolved as a structure with its own qualities.

Reproductive Morphology of Quercus (Fagaceae)

Details of inflorescence, floral, and fruit morphology have been studied in more than 120 species of Asiatic and American Quercus. Of the two subgenera, subgenus Cyclobalanopsis has fewer species but greater diversity of reproductive morphology than subgenus Quercus. Some character states of subgenus Cyclobalanopsis, such as more numerous stamens, male flowers sometimes grouped in dichasia, abortive ovules well developed, prominent intrusive septae in the nut, and lamellate cupules, are shared with Lithocarpus. The diversity of cupular sizes, coverage, and ornamentation raises questions about the adaptive nature, ecological function, and phylogeny of the cupule, which clearly has by now evolved as a structure with its own qualities.

In Vitro Culture and Plant Formation from Grape Cultivars with Abortive Ovules and Seeds

Abstract Normal embryos and seedling plants were obtained from abortive ovules and seeds of seedless grape cultivars ‘Perlette’, ‘Flame Seedless’ and ‘Sultanina’. Plant development was accompanied by callus formation only in ‘Perlette’. The best medium was Nitsch’s with the addition of 10-5m IAA and 10-6m GA3. Excision and culturing of ‘Flame Seedless’ ovules 49 days after anthesis gave higher germination percentages and more viable plants than excision and culturing at anthesis plus 28. Selfed ‘Perlette’ and ‘Perlette’ × ‘Flame Seedless’ ovules cultured at 52 days gave 11%, and the reciprocal cross over 16% well developed seedlings. The significance of the findings for breeding stenospermocarpic grapes is discussed.

The genus Eugenia (Myrtaceae) in southern Africa: Ontogeny and taxonomic value of the seed

Eugenia L. in southern Africa constitutes two coordinate groups of species (groups X and Y). Each group is characterized by a particular type of seed (types X and Y respectively). This study concerns the ontogeny of both seed types. Results are compared with the literature to evaluate its taxonomic significance. In both groups the ovules are hemi-campylotropous, occasionally tending to be ana-campylotropous, sessile or sub-sessile, bitegmic and crassinucellate. Usually only one ovule per ovary matures into an overgrown seed. Abortive ovules are transformed into ovulodes. Ovules in seed type X become amphitropous resulting in sub-reniform or oblong-globose seed. A short funicle is discernible; the hilum is not extended. The testa develops from the outer integument and is relatively thin (0,1 – 0,5 mm), not multiplicative and tends to be exotestal. Two areolae pervaded by vascular strands are present. Secretory cavities develop in the cotyledons. Starch, occasionally with unidentified spherical bodies, is the main storage product. Abundant endosperm is formed. Seed type Y is globose, pachychalazal and sessile with an extended hilum. The testa is relatively thick (0,5 – 1,0 mm), multiplicative, mesotestal and pervaded by vascular strands. Secretory cavities are absent from the cotyledons. Starch is the only storage product. Relatively little endosperm is formed. Generic rank is proposed for both groups. Group X is treated as congeneric with Eugenia s. str. whereas group Y probably represents a new generic segregate. Eugenia L. in suidelike Afrika word deur twee newegeskikte spesiegroepe (groepe X en Y) verteenwoordig. Elke groep word deur ’n besondere saadtipe gekenmerk (tipes X en Y onderskeidelik). Hierdie ondersoek handel oor die ontogenie van beide saadtipes. Die resultate word met literatuur-gegewens vergelyk ten einde die taksonomiese betekenis daarvan te evalueer. Saadknoppe van beide groepe is hemi-kampilotropies (soms geneig om ana-kampilotropies te wees), sittend of half-sittend, bitegmies en krassinusellêr. Gewoonlik ontwikkel slegs een saadknop per vrugbeginsel in ’n uitermate vergrote saad. Die oorblywende saadknoppe aborteer en is blywend. In die geval van saadtipe X word die saadknoppe amfitropies met die gevolg dat die saad halfniervormig of langwerpig-rond is. Die funikulus is baie kort en daar is geen vergroting van die hilum nie. Die relatief dun (0,1 – 0,5 mm) testa ontwikkel uit die buitenste integument, is nie veellagig nie en neig om eksotestaal te wees. Twee areole deurtrek met vaatstringe is teenwoordig. Sekreetholtes ontwikkel in die saadlobbe. Stysel, soms tesame met ongeïdentifiseerde bolvormige strukture, is die hoof-bergingsproduk. Baie endosperm word gevorm. Tipe Y sade is bolrond, pagichalasaal en sittend met ’n vergrote hilum. Die relatief dik (0,5 – 1,0 mm) testa is veellagig, mesotestaal en deurtrek met vaatstringe. Sekreetholtes is afwesig in die saadlobbe. Stysel is die enigste bergingsproduk. Relatief min endosperm word gevorm. Genusrang word vir beide groepe voorgestel. Groep X word beskou as kongeneries met Eugenia s. str., terwyl groep Y waarskynlik ’n nuwe genus verteenwoordig.

OVULE ABORTION IN ‘NONPAREIL’ ALMOND (PRUNUS DULCIS [MILL.] D. A. WEBB)

The earliest indication of ovule abortion in almond (Prunus dulcis [Mill.] D. A. Webb ‘Nonpareil‘) is the deposition of callose (as indicated by aniline blue fluorescence) 2 days after pollination which is 2 days before clear histological symptoms of ovule degeneration are evident and 6 days before fertilization of the viable ovule. Callose deposition begins in the chalazal region of the nucellus where the funicular trace enters the ovule and ramifies into the integuments. As ovule abortion progresses, callose deposition in the inner integument extends as a ring around the nucellus. Movement of the fluorescent dye disodium fluorescein (uranin) indicated that translocation from the vascular trace into abortive ovules becomes blocked at the chalazal position. The dye freely penetrates and diffuses into viable ovules but fails to penetrate abortive ovules. Lack of, or delayed and irregular, megagametophyte development was another characteristic of abortive ovules. Biochemical and histochemical analyses of abortive and viable ovules indicated that carbohydrate depletion parallels ovule abortion. These observations lead to the conclusion that ovule abortion is accompanied by blockage in metabolite supply although whether this blockage is the primary cause or a consequence of ovule abortion is uncertain.

Ovule Abortion in `Nonpareil' Almond (Prunus dulcis [Mill.] D. A. Webb)

The earliest indication of ovule abortion in almond (Prunus dulcis [Mill.] D. A. Webb ‘Nonpareil‘) is the deposition of callose (as indicated by aniline blue fluorescence) 2 days after pollination which is 2 days before clear histological symptoms of ovule degeneration are evident and 6 days before fertilization of the viable ovule. Callose deposition begins in the chalazal region of the nucellus where the funicular trace enters the ovule and ramifies into the integuments. As ovule abortion progresses, callose deposition in the inner integument extends as a ring around the nucellus. Movement of the fluorescent dye disodium fluorescein (uranin) indicated that translocation from the vascular trace into abortive ovules becomes blocked at the chalazal position. The dye freely penetrates and diffuses into viable ovules but fails to penetrate abortive ovules. Lack of, or delayed and irregular, megagametophyte development was another characteristic of abortive ovules. Biochemical and histochemical analyses of abortive and viable ovules indicated that carbohydrate depletion parallels ovule abortion. These observations lead to the conclusion that ovule abortion is accompanied by blockage in metabolite supply although whether this blockage is the primary cause or a consequence of ovule abortion is uncertain.

Ovule Abortion in Quercus (Fagaceae)

This study deals with the occurrence and relative abundance of four different types of abortive ovules in three species of Quercus. It was found that, contrary to previous literature, fertilization does not always occur in the abortive ovules. The most common type of abortive ovule is the one in which a normal embryo sac develops, yet fertilization does not occur. The absence of embryo sacs and the occurrence of empty embryo sacs account for abortion in other ovules. All types of abortive ovules can occur in the same ovary. It is proposed that all of the ovules that develop a normal embryo sac are potential seeds, but the first one to be fertilized suppresses the normal development of the others.

OVULE ABORTION IN QUERCUS (FAGACEAE)

This study deals with the occurrence and relative abundance of four different types of abortive ovules in three species of Quercus. It was found that, contrary to previous literature, fertilization does not always occur in the abortive ovules. The most common type of abortive ovule is the one in which a normal embryo sac develops, yet fertilization does not occur. The absence of embryo sacs and the occurrence of empty embryo sacs account for abortion in other ovules. All types of abortive ovules can occur in the same ovary. It is proposed that all of the ovules that develop a normal embryo sac are potential seeds, but the first one to be fertilized suppresses the normal development of the others.

The organization of the ranunculaceous flower with especial regard to the correlated variations of its constituent members

Detailed analysis of numerous ranunculaceous flowers demonstrate that, though the meristic variation be wide, the numerical relations between stamens and ovule production are very similar for most species. The relatively unspecialized flowers of Helleborus are shown to exhibit a negative correlation between stamen numbers and ovule numbers, but more specialized folliculate genera (e. g. Aconitum, Delphinium ) were found to present a positive correlation. In Anemone , with one fertile and abortive ovules, there is positive correlation between stamen numbers and fertile ovules, as also in genera with a single fertile ovule in the carpel ( Ficaria, Hepatica, Ranunculus, Thalictrum ). Data showing the ratio between the average number of stamens and the average number of ovules (or uniovulate carpels) is provided for fifty species belonging to thirteen genera of Ranunculaceae. In general this ratio is shown to vary within narrow limits but Ranunculus sceleratus is an exception which though vegetatively stable exhibits a very low ratio and marked variability of the usually stable calyx. From a detailed study of over 1200 flowers of Ranunculus repens evidence is furnished that the degree of variation and the number of members in the respective floral whorls is under genetic control but that, in flowers from plants producing extra petals this control is relaxed and even the calyx exhibits appreciable variation while floral members sharing the characters of sepals and petals, or petals and stamens, are met with on these individuals. The exceptionally prolonged flowering season of this species in 1972 permits the recognition of a definite meristic drift but affecting normal and abnormal flowers differentially. It is concluded that though the flower of Ranunculaceae is very variable as to the numbers of its parts the numerical relations between the members of the different floral whorls, particularly in the more specialized species, or strains of species, are relatively stable.

Fruit Tissue Injury by Frost to ‘York Imperial’ Apples1

Abstract The effects of freeze injury occurring at anthesis upon young developing fruit were studied anatomically. Slight injury was characterized by separation of the hypodermis from the outer cortex during the initial stages of fruit growth. Necrotic tissues were adjacent to the main part of the injury. The internal cortical tissues and vascular bundles in the core line were uninjured. The basin or fruit apex was sensitive to freeze injury resulting in stylar abscission, abortive ovules, and large breaks in the cortical tissue. Growth distortions in the outer cortex were evident 21 days after injury, indicating sensitivity to frost and to the initiation of corking. Wound healing occurred 1 week after full bloom with the development of callus or proliferated tissues which united the wound areas.

Floral bud reversion in Impatiens balsamina under non-inductive photoperiods

All floral buds of Impatiens balsamina plants exposed to 4 short-day (SD) cycles and then returned to long days reverted to vegetative growth. The same happened with the upper buds of plants receiving a larger number of SDs, even as many as 90 cycles. The reversal proceeded in a basipetal order. The number of floral buds and flowers increased, and their reversion to vegetative growth was delayed with increasing numbers of SD cycles. Depending upon the stage attained by the floral bud before the transfer of the plant to noninductive photoperiods one or more inner whorls of the flower were replaced by a vegetative apex. The tip of the placenta was able to resume vegetative growth even after the formation of fertile anthers and an ovary with abortive ovules, showing that the potentiality for reversion is maintained till quite late stages in floral bud development. Continuous exposure to SD cycles is required not only for the continued production of floral buds, but also for their development to mature flowers, indicating that the floral stimulus in this plant is not “self-perpetuating”.

THE DOMINANT ROLE OF THE EPIDERMIS IN LEAVES OF ADIANTUM

the fertile ovule lies in the locule of the carpel opposite, not in the locule of its own carpel. Vestigial ovules are usually present in the abortive carpels and are usually absent in the carpel containing the fertile ovule. The carpel with the welldeveloped locule, therefore, is usually sterile, though it contains the single fertile ovule in the flower. The vascular supply of the ovary consists of five peripheral bundles and a central bundle. The central bundle usually divides in the vicinity of the ovule attachnent, primitively, into three ventral bundles and an ovular bundle. Reduction stages occur in the various species showing the loss of one, then both sterile ventral bundles, followed eventually bv the disappearance of the fertile ventral bundle. The ovular bundle mav be double at its origin, but it fuses before entering the ovule. The ovular supply, therefore, like that of the fertile ovules in the Linnaeeae, is douHle. Some species show vestiges of ovular traces to some of the abortive ovules. Lateral and dorsal carpellary traces for the three carpels are variously derived from the peripheral and central bundles. Four of the peripheral bundles divide at the top of the ovary. In all, ten bundles are formed,-five petal traces, five stamen-sepal bundles. In manv of the species, flowers occur with no fertile ovule, though one abortive ovule is relatively betterdeveloped than the rest. The supply is simnilar to that of the normal ovary. The relatively welldeveloped abortive ovule is delimited in the upper part of the ovary around thee ovular bundle in the center. It emerges in the center of a 3-lobed locule which contains even more reduced vestigial ovules attached to the three placentae. It is evident that there has been enlargement and atrophy of organs, and adnation and cohesion of parts and their vascular supply in the evolution of the genus. Reduction stages are found in the dorsal and marginal carpellary supply; the supply to fertile and abortive ovules; the number, position, and development of abortive ovules; the peripheral bundles; and the sepal traces. Comparative study of the internal morphology and vascular anatomy of the flower indicates that V. Sieboldii is the most primitive; FT. Opulus, the most advanced. Also primitive are V. Cartes i, V. Lantana and V. dentatum. More advanced are V. rhitidophyllum, V. cassinoides, V., acerifolium, V. tri.lobum anid others.

POLLEN‐ AND SEED‐STERILITY IN HYBRIDS

of hybrids in various forms and degrees is a phenomenon so frequently presented to the plant breeder and geneticist that in some form and in some degree it is rather to be expected. The first problem in its study demands a critical examination to determine in the life history the place of those conditions that bring about the sterility in question. In earlier days the gametes were generally expected to carry the blame of failure to reproduce the line. More recent studies have shown that responsibilities for sterility cannot be so easily placed. Sterility, as expressed by varying proportions of abortive pollen and abortive ovules, is very common, and since it is easily recognized this manifestation of sterility has received the greatest share of attention. It is expressed by failure of the pollen grain to attain full size, the structure shriveling and usually losing its protoplasmic contents. In a like manner, the megaspore or embryo sac does not reach a normal development in the ovule. Such behavior results in failure to produce gametes, and cytological studies, as far as they have gone, indicate that this form of sterility, at least frequently, has its causation in irregularities of the reduction divisions which immediately precede the differentiation of microand megaspores. During these mitoses spindles may not be normal in form, chromosomes may be distributed in varying and irregular numbers, and the preparations for the reduction divisions may show abnormalities. Such phenomena clearly indicate a breakdown in the mechanism of nuclear division at this critical stage in the life history. It seems reasonable to assume in these cases that the hybrid must carry a germ plasm the structural elements of which can not conduct themselves in the orderly manner so characteristic of meiosis. Speculation on the reasons for the obvious breakdown of the cell and nuclear mechanism at this point in the life history would lead us too far afield for the purposes of this paper. It seems clear, however, that the causes lie in the heterozygous nature of the germ plasm, since we do not find this form of sterility in pure material. Abnormalities of chromosome distribution are clearly invited when the two sets are of different genetical constitution, since irregularities of segregation are rendered much more likely. It should not be assumed, however, that the presence of abortive pollen and abortive ovules is proof positive that the parent plant is hybrid, although l Read in the symposium on Sterility in Plants, at the joint meeting of Section G of the American Association for the Advancement of Science, the Botanical Society of America, and the American Phytopathological Society, at Cambridge, December 27, I922. 462

Studies of the Pollen Tubes and Abortive Ovules of the Globe Mutant of Datura

Studies of the Pollen Tubes and Abortive Ovules of the Globe Mutant of <i>Datura</i>