Pollen–pollen interactions in Betula pendula in vitro

Direct pollen interactions, as well as interactions mediated by a recipient, can have a remarkable influence on pollen fertilization ability. Under conditions of pollen competition it could be advantageous if pollen grains interfered with the germination of other pollen. The aim of this study was to find out if there are direct negative or positive pollen–pollen interactions between pollen grains from genetically slightly different donors. The in vitro germinability of the pollen from several Betula pendula Roth clones was investigated. The pollen interactions between the clones were examined pairwise by using equal pollen mixtures. In three of the eight cases the germination percentage of the pollen mixture was significantly higher than the average germination percentage of the separate clones that formed the mixture, which indicates some type of interaction between the pollen populations. We found only positive interactions between the pollen of clones. This study also documented density-dependent germination of pollen grains in vitro (=pollen population effect). Adding an aqueous pollen extract to the incubation medium increased the germination percentages of poorly germinating pollen and small pollen populations. Germination-stimulating effects were found to exist both with fresh and dead pollen. Such direct pollen–pollen interactions could be explained by specific water-soluble substances diffusing from pollen grains.     

Efficient plant regeneration through somatic embryogenesis from callus induced on mature rice embryos (Oryza sativa L.)

To obtain a reproducible efficient procedure for regeneration of rice plants through somatic embryogenesis from callus four published methods of callus induction and regeneration were compared. Callus was initiated from mature embryos of the Japonica cultivar Taipei 309 of rice (Oryza sativa L.). The number, mass and morphology of the callus formed on the scutellum were dependent on the medium used. A limited humidity and an optimal aeration of the culture vessels enhanced the frequency of embryogenesis and plant regeneration. A method described by Poonsapaya et al. (1989) was found to be the most efficient and was slightly modified. As a result 98% of the T309 embryos formed callus, of which 63% regenerated into plants. Each callus yielded an average of 6 plants. Plant morphology, fertility and seed set of the regenerants were found to be normal.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - IAA 3-indole-acetic acid - BA 6-benzyladeninepurine - S.E.M. standard error of mean     

Immunocytochemical localization of allergenic protein (Ole e I) in the endoplasmic reticulum of the developing pollen grain of olive (Olea europaea L.)

The monoclonal antibody OL-1 and transmission electron microscopy were used to locate immunologically the major allergen of olive pollen. Ole e I, during pollen grain development. Within the pollen grain, allergenic proteins are located in the cisternae of the rough endoplasmic reticulum. Our findings indicate that the synthesis of these proteins starts in the vegetative cytoplasm of olive pollen during the early maturation stage.Dedicated to Professor Andreas Sievers on the occasion of his retirement     

The morphological variability within a population of coffee somatic embryos produced in a bioreactor affects the regeneration and the development of plants in the nursery

A 1-liter bioreactor was used to obtain approximatively 800 Coffea arabica somatic embryos, 86% of which reached the `germinated' stage but with morphological heterogeneity. The population was sub-divided into three categories according to cotyledon area: 'small', 'medium' and 'large', that amounted to 32%, 36% and 4.5%, respectively. The effect of embryo morphology on plantlet conversion after direct sowing in soil and on plant development in the nursery was investigated. Somatic embryos with large cotyledons had only a 25% plantlet conversion rate, whereas somatic embryos with small to medium-sized cotyledons had conversion rates of 47% and 63%, respectively. The vigour of the aerial and root systems of regenerated plantlets at the end of the plant conversion stage was also affected as the embryos with small, medium and large cotyledon mostly regenerated small plantlets (0.5–1.5 cm), medium plantlets (1.5–2.5 cm) and large plantlets (2.5–5 cm), respectively. When transplanted in plastic bags, these 3 populations of plantlets exhibited distinct development rates. They had an initial slow growth phase, which was much longer for the small plantlets, followed by a rapid growth phase. After 40 weeks in the nursery, an analysis of the growth parameters of aerial and radical systems showed that the vigour of the plants was strongly related to the vigour of the plantlets transplanted. The heterogeneity of somatic embryos in the bioreactor affected both the plant conversion efficiency in soil and the plant growth in nursery, where it mainly resulted in retarded growth, primarily in plantlets derived from the somatic embryos with small cotyledons.     

The bps signal: Embryonic arrest from an auxin-independent mechanism in bypass triple mutants

Long-distance signaling is essential for coordination of plant development and environmental responses. We originally isolated a tiny mutant named bypass1 (bps1), which has defects in shoot and root development. The bps1 roots overproduce a mobile signal (bps signal) that arrests both root and shoot development. Our recent study demonstrated that all three BPS gene family members prevent ectopic synthesis of the same bps signal.bps multiple mutants show progressively more severe developmental defects. An embryogenesis analysis revealed abnormal cell divisions in all meristem lineages of bps triple mutants. These defects appear to be auxin independent, and arise prior to changes in PLT1 and PLT2 expression.     

New theory of uterovaginal embryogenesis

Background: The explanation of uterine and vaginal embryogenesis in humans still poses many controversies, because it is difficult to assess early stages of an embryo. The literature review revealed many disagreements in Mullerian theory, inciting some authors to propose new embryological hypotheses. In the original Mullerian theory: the paramesonephral ducts form the Fallopian tubes, uterus and vagina; the mesonephral ducts regress in female embryos. Aims: The aim of this article is to investigate the development of Mullerian ducts in humans, using comparative analysis of fundamental embryological theory and various utero-vaginal anomalies. Material and methods: Between 1998 and 2015, 434 patients with various uterovaginal malformations had been operated on at the Scientific Centre of Obstetrics Gynaecology and Perynatology in Moscow. The anatomies of the uterovaginal malformations in these patients were diagnosed with ultrasound and MRI and then verified during surgical correction by laparoscopy. Results: A systematic comparison of uterovaginal malformations to those in the literature has allowed us to formulate a new theory of embryonic morphogenesis. The new theory is significantly different: ovary, ovarian ligamentum proprium, and ligamentum teres uteri derive from gonadal ridges; Fallopian tubes and vagina completely develop from mesonephral ducts. The uterus develops in the area of intersection between the mesonephral ducts with gonadal ridges by the fusion of the two. Conclusions: The new theory may to induce future embryological studies. The hypothetic possibility that the ovary and endometrium derive from the gonadal ridges could be the key to understanding the enigmatic aetiologies of extragenital and ovarian endometriosis.     

Maturation and hatching of eggs from silkworm ovaries preserved in liquid nitrogen

Ovarian imaginal discs prepared from fifth-instar larvae of the silkworm, Bombyx mori were treated with graded concentrations of glycerol, cooled at a rate of 1°C/min to ?35°C and preserved in liquid nitrogen for 2 days or more and then rapidly thawed (500°C/min). The frozen and thawed ovaries were transplanted into fifth-instar female larvae, in which more than 20% of the ovaries developed to produce mature eggs with a chorion according to the state of host development. By parthenogenetic activation, the mature eggs started embryogenesis and hatched to produce larvae. About 50% hatching occurred in the eggs developed in a C 108 × Cambodge host, and about 10% in a C 108 × Aojuku host. The hatched larvae completed post-embryonic development as did the normal larvae.     

Paternal inheritance of mitochondria in rapeseed (Brassica napus)

Summary Transfer of a mitochondrially associated plasmid following sexual crosses in Brassica napus rapeseed suggested that paternal mitochondria were being transferred to the cytoplasm of the egg. To examine this possibility further, plants carrying the chloroplast (cp) marker of triazine resistance, but which had lost the plasmid associated with the mitochondria of this cytoplasm, were crossed as females to males carrying the polima cytoplasm. The males carried a nuclear fertility restorer gene on an extra chromosome to overcome the male sterility marker conferred by the mitochondria of this cytoplasm. Approximately 10% of the F₁ progeny displayed the male sterility and flower morphology of the male parent. Mitochondrial (mt) DNA from the progeny showed the combined restriction patterns of both parents, but this rut heterogeneity did not continue into subsequent generations. All progeny retained the cp DNA restriction patterns of the maternal plant as well as resistance to the herbicide atrazine. To date, sexually mediated cybrid plants have shown no morphological abnormalities and have maintained their unique combination of cp and mt traits through several sexual generations.     

The significance of ant and plant traits for ant pollination in Leporella fimbriata

Summary Ant metapleural glands secrete surface antibiotics that affect pollen as well as bacteria and fungi. This may be one reason why ant pollination is rare. It is predicted that pollination by ants is possible only in the presence of certain ant and/or plant traits. Two traits are investigated; first, absence of the metapleural glands, and second, the presence of stigmatic secretions that insulate pollen from the ant integument. The pollinator of the orchid Leporella fimbriata is the ant Myrmecia urens. Only one caste is involved, the winged males, and they differ significantly from the queen and worker castes in that they do not possess metapleural glands. This paper reports experiments which test for differential effects on pollen between the males and other castes and evaluates the importance of stigmatic secretions. The results show that the absence of metapleural glands makes no difference as all three castes have strong disruptive effect on pollen artificially applied to the integument. However, during pollination the orchid secures the pollen mass to the ant surface by stigmatic secretions and normal pollen function, fruit production and seed set occur. It appears that both ant and plant traits are pre-adaptive having evolved for functions other than ant pollination.This is contribution number 98 to the Research Unit for Biodiversity and Bioresources, Macquarie University