Academic literature on the topic 'Pistil cytology'

Amur grape (Vitis amurensis) is a dioecious species. To elucidate the time of and reason for pistil abortion in male amur grape from the perspective of cytology, we observed the sections of pistil of a male line during its development using optical and transmission electron microscopes. The abnormity in the morphology of nucellar cell and the development of various organelles appeared before the abnormity of functional megaspore mitosis. Programmed cell death (PCD) of the nucellar cells might be an important reason for mitosis disorder, leading to the abortion of pistil in male flower. However, the abortion can be eliminated by forchlorfenuron treatment, resulting in the recovery of functional pistil in male amur grape. This study provides cytological information on the gender conversion mechanism in male amur grape, which can promote gender determination studies in Vitis species.

Aspects of the breeding system, floral morphology and pistil cytology were studied in three trees each of E. spathulata, E. cladocalyx and E. leptophylla. E. spathulata and E. leptophylla were found to be highly self incompatible, setting very low levels of seed from controlled self pollination. E. cladocalyx trees ranged from self compatible to self incompatible. Reductions were seen in both the number of capsules and the numbers of seeds per capsule, from self pollination. The mechanism of self incompatibility was investigated in the pistil by following the success of cross and self pollinations with fluorescence microscopy. In E. cladocalyx and E. leptophylla no reduction in ovule penetration was seen from self pollination while in E. spathulata a significant reduction was seen in two trees but not the third, indicating that the post-zygotic mechanism of self incompatibility operates in all three species, and with mixed pre-zygotic and post-zygotic mechanisms in E. spathulata. Floral architecture differed between the three species in the structure of the inflorescence units, flower morphology, and anther, pollen and ovule numbers per flower. Pistil cytology was similar for all three species but differed in the length of the stylar canal, degree of sclerotinisation, stigma morphology and volume of transmitting tissue. The implications of floral structure and of the location and extent of outcrossing control are discussed in relation to seed genotypes and seed output.

This study was undertaken to determine the cytology, method of reproduction, and flowering behaviour of three Paspalum species. Paspalum plicatulum has long been considered a segmental allotetraploid that reproduces by obligate apomixis with the type being apospory followed by pseudogamy. Paspalum simplex is an apomictic autotetraploid species, while P. chaseanum is a rare species for which no information regarding cytology and reproduction is available. This investigation concerns diploid cytotypes (2n = 2x = 20) of P. plicatulum and P. simplex that were recently collected in subtropical South America. In addition, two accessions of P. chaseanum were also recorded and both had 2n = 2x = 20 chromosomes. Meiosis showed regular bivalent chromosome pairing. Embryological observations indicated that the three species reproduce sexually at the diploid level. Pollen–pistil interaction following self-pollination suggested the presence of a self-incompatibility system responsible for allogamy. The results indicate that P. plicatulum and P. simplex complexes consist of diploid sexual allogamous cytotypes in addition to the known tetraploid apomictic cytotypes. Diploid strains constitute a source of sexuality for plant improvement. Chromosome doubling will likely produce sexual tetraploids to be used as females in crosses with natural apomictic tetraploid biotypes. Since diploid self-incompatible sexual Paspalum plants usually have apomictic tetraploid co-specific counterparts, the self-incompatible diploid P. chaseanum described in this study warrants further exploration for its apomictic counterpart.

Autotetraploids were colchicine-induced in Triticum monococcum and, upon comparison to their diploid progenitor, possessed the following characteristics: (i) their cells were on the average 20.8% larger; (ii) plant height was reduced by 15% and tillering by 37.5%; (iii) spikes, 1000-kernel weight, pistil size (length (L)/weight (W), and leaf size (L/W) were 53.9, 51.2, 80/57.1, and 60/26.4% larger, respectively; and (iv) they were 12.4% earlier in heading. Observed mean numbers of univalents, bivalents, trivalents (linear, convergent, and indifferent coorientations), and quadrivalents (convergent and parallel alignments only) per microsporocyte at metaphase I were 0.62, 9.86, 0.23, and 1.74, respectively; 65.4% of all meiocytes possessed bivalents and (or) quadrivalents and produced balanced meiotic products; 34.6% also possessed univalents and (or) trivalents and, therefore, produced balanced and unbalanced meiotic products. The actual 70.9% balanced meiotic products falls within the calculated range of 65.4–81.3%. Our tetraploids breed true. Evidence and reasons for this are discussed. The fertility of our tetraploids was high (79.8%). Irregular chromosome behaviour during meiosis may play a decisive role in determining the fertility level. Genic factors may also be involved. Methods of improving fertility and whether chromosomal factors alone are responsible for tetraploid fertility levels are discussed. Mature seed from reciprocal 2n = 4x × 2n = 2x crosses was shrivelled because of endosperm collapse and did not germinate. Thus, embryo excision and culturing on artificial medium was required to obtain viable autotriploids.Key words: Triticum monococcum, autotetraploid, cytology, breeding behavior, fertility, morphology.

Mature triploid seed from reciprocal (2n = 4x × 2n = 2x) crosses in Triticum monococcum was minute and shrivelled because of endosperm collapse and therefore failed to germinate. This necessitated the excision of embryos from successful pollinations and their growth in vitro to ensure subsequent germination so as to obtain viable and vigorous autotriploids. A comparison of these triploids with their diploid and tetraploid progenitors revealed that cell size, kernel weight, and pistil size increased with an increase in ploidy level. However, unlike other species, optimum expression was observed in these triploids for plant height, tillering, size of spikes, number of spikelets/spike, and leaf size. Earliness, althoughenhanced in tetraploids relative to diploids, was delayed in the triploids. Mean numbers of univalents, bivalents, and trivalents per microsporocyte were 2.65, 2.60, and 4.38, respectively. Only chains (93.5%), which formed V-shaped metaphase I (MI) configurations, frying pan (5.0%), and Y-shaped (1.5%) trivalent associations occurred. On the average, two reciprocal exchanges occurred per bivalent and trivalent. Trivalents corriented randomly at MI. At anaphase I, all sets of three homologues segreated randomly to the two poles, lagging univalents always divided equationally, and only meiocytes with such chromosomes formed micronuclei. The reasons for similarities and differences in meiotic behaviour of T. monococcum triploids with those of other species are discussed. Confirmation of the conclusions drawn with respect to the cytology of the triploids was obtained from similar cytological observations with primary single trisomics. These triploids produced euploids, primary single trisomics as well as some double and triple trisomics all of which differed phenotypically from diploids. Triticum monococcum, like most diploid species, is highly intolerant of aneuploidy. Possible reasons for the differences in levels of tolerance of aneuploidy in species like T. monococcum and those like Petunia hybrida, which are highly tolerant of aneuploidy, are discussed. Pollen fertility was high and seed fertility was very low. Reasons for the latter as well as the high fertility in species that are highly tolerant of aneuploidy and allotriploids are discussed.Key words: Triticum monococcum, autotriploid, trisomic, cytology, breeding behavior, fertility, morphology.

CONTEXT AND OBJECTIVE: Fine-needle aspiration biopsy has been accepted worldwide for breast lesions. However, some questions remain, including the appropriateness of the puncture method. The objective of this work was to compare aspirates obtained by the auto-vacuum device and by the syringe pistol holder. DESIGN AND SETTING: Randomized trial for validation of diagnostic method, at Hospital das Clínicas da Universidade Federal de Goiás and Hospital Araújo Jorge, Goiânia. METHODS: 351 patients presenting breast lumps underwent fine-needle aspiration biopsy, either with the auto-vacuum device or the syringe pistol holder. A single cytopathologist analyzed all of the cytology slides. The rates of insufficient material, cellularity, cell distortion and background hemorrhage were evaluated. RESULTS: The percentages of insufficient material were 16% and 22% (p = 0.18), for the auto-vacuum and pistol aspirates, respectively. Good cellularity was seen in 34% of auto-vacuum and 29% of pistol samples (p = 0.4). Cell distortion was seen in 31 and 26 cases, respectively (p = 0.7). Background hemorrhage occurred in 63 (35%) and 54 cases (31%) (p = 0.2), for auto-vacuum and pistol. The sensitivity was 88% and 86%; specificity 99% and 100%, positive predictive value 96% and 100%, negative predictive value 96% and 95% and total accuracy 76% and 75% for the auto-vacuum and pistol, respectively. CONCLUSION: The results obtained from the two fine-needle aspiration biopsy methods were equivalent. Therefore, the auto-vacuum device is a good option for obtaining aspirates for cytology.

Inter and intra-specific hybridization is a powerful breeding method for crop improvement and it has potential to broaden the genetic base of the cultivated species. M. charantia var. muricata is considered as a wild progenitor of bitter gourd (M. charantia) and it has important novel genes for biotic and abiotic stress tolerance. In the present experiment, conducted during the 2016–17 and 2017–18, intra-specific hybrids were produced among M. charantia var. charantia and M. charantia var. muricata and these were characterized for plant morphology, pollen-pistil compatibility, cytology and molecular relation among the parents and hybrids. In both direct and reciprocal crosses, the crossability percent was nearly 90% with high percent of pollen viability. The morphological traits of the parents were highly diverse and the hybrids showed intermediate pattern of character expression. The pollen-pistil behaviour and compatibility reaction were studied for the first time and observed higher per cent of compatibility in direct cross (M. charantia var. charantia × M. charantia var. muricata; 90.98%) and comparatively lower in reciprocal cross (M. charantia var. muricata × M. charantia var charantia; 84.43%). Cytological and molecular marker (SSR) techniques were used for hybridity confirmation.

This study investigated the reproductive biology of four Eucalyptus species of the subgenus Symphyomyrtus; E. spathulata, E. cladocalyx and E. leptophylla of the section Bisectaria, and E. Ieucoxylon of the section Adnataria. Aspects of the breeding system, floral morphology and pistil cytology were studied in three trees each of E. spathulata, E. cladocalyx and E.leptophylla. E. spathulata and E. Ieptophylla were found to be highly self incompatible, setting very low levels of seed from controlled self pollination. E. cladocalyx trees ranged from self compatible to self incompatible. Reductions were seen in both the number of capsules and the numbers of seed per capsule, from self pollination. The mechanism of self incompatibility was investigated in the pistil by following the success of cross and self pollinations with fluorescence microscopy. ln E. cladocalyx and E. leptophylla no reduction in ovule penetration was seen from self pollination while in E. spathulata a significant reduction was seen in two trees but not the third, indicating post-zygotic mechanisms of self incompatibility operating in all three species, with some pre-zygotic control in E. spathulata. Floral architecture differed between the three species in the structure of the inflorescence units, flower morphology, and anther, pollen and ovule numbers per flower. Pistil cytology was similar for all three species but there were differences in the length of the stylar canal, the degree of sclerotinisation of the style, stigma morphology and volume of transmitting tissue. The breeding system of E. leucoxylon was investigated with emphasis on the unusual features of gynodioecy and secondary pollen presentation. Fifty seven percent of trees in the study population were found to be male sterile, with pollen grains aborted during development between tetrad formation and anthesis. Hermaphrodite trees presented 93 percent of pollen grains on the upper style and stigma, with only seven percent of pollen grains remaining on the anthers. In the absence of pollinators hermaphrodite trees set low levels of autogamous seed compared with open pollinated pistils. Counts of pollen tubes in open pollinated pistils of each morph revealed that female trees were pollen limited in the study population. Multilocus estimates of outcrossing rates were determined for female isozyme electrophoresis. Female trees showed values of (t) approaching 1.0, indicating complete outcrossing, while hermaphrodite trees showed significant levels of selfed seed in open pollinated seed crops, but still maintained an outcrossing rate higher than that reported for most eucalypts. The pollen-pistil interaction was investigated in three intraspecific, 57 interspecific and six intergeneric crosses using the three species Eucalyptus spathulato, E. cladoclayx and E. leptophylla as female parents. Interspecific prefertilisation isolation was found to occur in the pistil and manifested as a number of pollen tube abnormalities in the style and ovary associated with a lowered probability of ovule penetration. The major selection points in the pistil were the upper style and the ovary. The severity of abnormalities and the probability of pollen tube arrest in the pistil was proportional to the taxonomic distance between parent species. Ovule penetrations were seen mainly in crosses within the section Bisectaria or between the sections Bisectaria and Adnataria. Pollen storage, style length and mean maximum temperature during the flowering period of the male parent had no significant effect on pollen tube growth in the crosses used. Intra and interspecific combinations which showed ovule penetration were repeated the following flowering season and monitored for seed set. Most combinations produced capsules although only combinations within the section Bisectaria and between the sections Bisectaria and Adnataria set viable seed. There was considerable variation between years in cross compatibility with some female trees which showed no ovule penetration in the first year setting viable seed in the same combinations the following year. Many close combinations set levels of seed approaching intraspecific cross pollinations, while interspecific crosses outperformed intraspecific self pollinations in both capsule set and the number of seeds per capsule. Some crosses between the sections Bisectaria and Adnataria showed hybrid breakdown at the early seedling stage. Hybrid parentage was confirmed through intermediate seedling morphology. The findings of this study have implications for the ecology and conservation of Eucalyptus species, for breeding strategies in tree improvement programmes and for the taxonomic relationships of the species.
Thesis (Ph.D.) -- University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 1991