Smaller Cotyledons Research Articles

Gross as well as microscopic anatomy and physiological functions of fetal placenta in Jaffrabadi buffaloes

The present study was conducted to know the gross morphology and histo-morphological structure of fetal placenta in Jaffrabadi buffaloes. Parameters like calf weight, placental weight, numbers, and size of cotyledons were observed in Jaffrabadi buffaloes and morphologically, fetal cotyledons were convex and non-pendunculated in Jaffrabadi buffaloes were found. Histological studies of small and large cotyledons showed extensive branching of secondary and tertiary villi that were longer, slender, and well developed in Jaffrabadi buffalo. A less developed basal lamina was seen in small cotyledon whereas developed basal lamina with numerous capillaries and connective tissue were observed in the large cotyledon. The diameter of trophoblast giant cells (TGC) in larger cotyledons were significantly (P<0.05) than the small cotyledons in expelled placenta at full term in Jaffrabadi buffaloes. A distinct distribution of carbohydrate and lipids in cotyledons were observed between large and small cotyledons as evident by acid mucopolysaccharides, neutral polysaccharides, and sudanophilic staining. Specific staining for calcium with Alizarin red stain showed that calcium is not present in a noticeable amount in small and large cotyledons. Isolation and culture of Jaffrabadi placental cells in M-199 medium with antibiotics and 2% FBS results in the efficient production of progesterone, estrogen, and testosterone. This study has shown that trophoblast cells are the actual sites for steroid hormone production. These cultured placental cells (1x106 cells/ ml) produce Progesterone, Estradiol-17β and Testosterone in the range of 1.72 to 2.12, 16.03 to 19.51 and 0.51 to 0.58 ng/ml, respectively in Jaffrabadi buffalo.

Low pH stress activates several genes for lateral root formation and detoxification of aluminum ions in Cotton plants

In low pH condition of soils (pH<5), Al is solubilized into a phytotoxic form Al(H2O)63+ and inhibits the plant root growth and development. Precisely, during low pH stress (e.g., pH 4.75), aluminum compound converts into its ionic form and becomes higher in level which is a limiting factor for plant root growth and seedling formation. Under aluminum (Al) toxic conditions, the organic acid transporters for example citrate and malate transporters in plasma membrane are involved in organic acid release and form non phytotoxic stable complexes with Al3+ in the rhizosphere. The study showed that, the cotton seedlings exhibited very sensitive phenotypes to low pH stress conditions due to high accumulation of ionic Al stress, the seedlings displayed retarded primary, secondary root growth and small cotyledons. These results indicated that cotton plants are susceptible to low pH condition.. As a whole without fine divisions the root system becomes corraloid in structure which will be having squat secondary roots. Plant has developed a natural defense mechanism in order to combat this unfavorable environment. Expression profile and Al complexation with organic acid exudates studies clearly revealed that both GhALMT1 and GhALS3 genes are involved in Al3+detoxification mechanisms. The remarkable expression was detected for GhALS3 under both low pH and aluminum stress condition in comparison to wild type untreated control whereas GhALMT1 expression was only activated under Al3+ stress condition. Our study, displayed enhanced citrate and malate excretion values in the wild type plants which are treated with Al and H+ stress. Thus, it can be clearly mentioned that GhALMT1 and GhALS3 is playing a significant role in low pHstress tolerance of cotton plant.

Placental Characteristics Classification of Various Native Turkish Sheep Breeds.

Simple SummaryThe aim of this study was to classify placental characteristics of Akkaraman, Morkaraman, Karayaka, Awassi, Malya, and Bafra native sheep breeds using the hierarchical clustering method. As a result, six breeds were separated into three clusters: the first cluster consisted of Bafra, Karayaka, and Awassi breeds; the second consisted of Akkaraman and Malya breeds; and the third cluster included only the Morkaraman breed.The aim of this study was to classify placental characteristics of Akkaraman, Morkaraman, Karayaka, Awassi, Malya, and Bafra sheep breeds using the hierarchical clustering method. In total, 240 individual data records were used as experimental material. Placental characteristics such as total cotyledon surface area, small and large cotyledon length, small cotyledon depth, etc. were used as explanatory variables to classify the breeds’ characteristics. Hierarchical clustering was used with the nearest neighbour method with Euclidean distance in order to classify the sheep breeds’ variations. As a result, six breeds were separated into three clusters: the first cluster consisted of Bafra, Karayaka, and Awassi breeds; the second consisted of Akkaraman and Malya breeds; and the third cluster included only the Morkaraman breed. Bafra and Karayaka were pointed as the nearest breeds, with a similarity of 98.7% in terms of placental characteristics. The similarity rate of the Akkaraman and Malya breeds was at a level of 97.5%, whereas it was 96.8% for Bafra, Karayaka, and Awassi breeds. The similarity of Akkaraman, Karayaka, Awassi, Malya, and Bafra sheep breeds was estimated as 95.7%. The overall similarity was found to be at a level of 93.2% among sheep breeds. The outcomes of the study might be useful as a selection tool for reproductivity and can be used to select the breed to be reared.

Mitochondrial heat-shock cognate protein 70 contributes to auxin-mediated embryo development.

In Arabidopsis thaliana, mitochondrial-localized heat-shock cognate protein 70-1 (mtHSC70-1) plays an important role in vegetativegrowth. However, whether mtHSC70-1 affects reproductive growth remains unknown. Here, we found that the mtHSC70-1 gene was expressed in the provascular cells of the embryo proper from the early heart stage onward during embryogenesis. Phenotypic analyses of mthsc70-1 mutants revealed that mtHSC70 deficiency leads to defective embryo development and that this effect is mediated by auxin. In addition to a dwarf phenotype, the mthsc70-1 mutant displayed defects in flower morphology, anther development, and embryogenesis. At early developmental stages, the mthsc70-1 embryos exhibited abnormal cell divisions in both embryo proper and suspensor cells. From heart stage onward, they displayed an abnormal shape such as with no or very small cotyledon protrusions, had aberrant number of cotyledons, or were twisted. These embryo defects were associated with reduced or ectopic expression of auxin responsive reporter DR5rev:GFP. Consistently, the expression of auxin biosynthesis and polar auxin transport genes were markedly altered in mthsc70-1. On the other hand, mitochondrial retrograde regulation (MRR) was enhanced in mthsc70-1. Treatment of wild-type plants with an inhibitor that activates mitochondrial retrograde signaling reduced the expression level of auxin biosynthesis and polar auxin transport genes and induced phenotypes similar to those of mthsc70-1. Taken together, our data reveal that loss of function of mtHSC70-1 induces MRR, which inhibits auxin biosynthesis and polar auxin transport, leading to abnormal auxin gradients and defective embryo development.

Direct defense of common bean accessions against two-spotted spider mite (Tetranychus urticae Koch.) attack

To find the direct defense of seedling resistance of common beans, by resistant mechanisms, morphological and physiological attributes of ten cultivars (Naz, Dorsa, Akhtar,KS41128, 65-062-107, 65-071-98, 65-071-306, 65-071-410, 65-071-400, and 65-071-405) were evaluated against two-spotted spider mite in 2017 at Bu-Ali Sina university, Hamedan, Iran. Among four kinds of resistant mechanisms such as antixenosis, antibiosis, tolerant tests and PRI index, both antixenosis and tolerance mechanisms determined to be the most accurate tests in the evaluating of common bean resistance against TSSM attack. Germination delay, development and fast growth, early maturity, erected posture, small cotyledon area, the more leaf thickness along with the dark-colored demonstrated were the escape mechanisms of common beans tolerant genotypes against TSSM attack. Some epidermal traits such as the first defense barrier on common bean like hook-shaped and high density of trichome especially on abaxial epidermis by having trapping behavior showed high relation with tolerant genotypes. In fact, in tolerant beans, related-traits to trichome on leaves entrapped the body parts of TSSM such as leg tarsi, mouthpart and ovipositor and prevented to move, feed and reproduction of mites and therefore, these features decreased damage to leaf area of Phaseolus vulgaris as well. The 65-071-98, 65-062-107 genotypes and NAZ, were certainly categorized as the most tolerant cultivars while Akhtar and 65-071-400 were introduced as the most susceptible accessions of common beans, respectively.

Estimating of Birth Weight Using Placental Characteristics in The Presence of Multicollinearity

In this study, it was aimed to compare the performance of proposed estimators in the presence of multicollinearity that will be used in regression analysis as an alternative to Least Squares. Birth weight was estimated by using placental features such as sex, placental efficiency, total cotyledon numbers, large cotyledon weight, medium cotyledon weight, small cotyledon weight, large cotyledon number, medium cotyledon number, small cotyledon number, large cotyledon width, medium cotyledon width, small cotyledon width, large cotyledon length, medium cotyledon length, small cotyledon length, large cotyledon depth, medium cotyledon depth, small cotyledon depth for Bafra sheep breed. In the presence of multicollinearity, more reliable models can be obtained by using some estimator. The performances of the Ridge and Liu estimators, which are suggested methods for this situation, were compared. MSE, RMSE, rRMSE, MAPE, R2, and AIC were used as model comparison criteria. As a result of, in the presence of multicollinearity; Liu estimator is recommended as an alternative method to Least Squares.

ENO2 Affects the Seed Size and Weight by Adjusting Cytokinin Content and Forming ENO2-bZIP75 Complex in Arabidopsis thaliana.

Arabidopsis thaliana ENO2 (AtENO2) encodes two proteins AtENO2 (enolase) and AtMBP-1 (c-Myc binding protein 1-like). The loss of AtENO2 function causes the constitutive developmental defects which are correlated with reduced enolase activity, but not AtMBP-1 transcript abundance. However, the regulation mechanism of AtENO2 on the seed properties is still not clear. In this study, we found that the mutation of AtENO2 reduced the seed size and weight. The level of glucose in seed was significantly elevated but that of starch was decreased in AtENO2 mutants compared to WT plants. We also found that AtENO2 mutation reduced the content of cytokinin which resulted in smaller cotyledons. The RNA-seq data showed that there were 1892 differentially expressed genes and secondary metabolic pathways were significantly enriched. Instead of AtMBP-1, AtENO2 protein interacted with AtbZIP75 which may mediate the secondary metabolism. Therefore, ENO2 alters the size and weight of seeds which is not only regulated by the content of cytokinin and secondary metabolism, but may be affected by the interaction of ENO2 and bZIP57. These results are helpful to understand the novel function of AtENO2 which provide a foundation for further exploration of the key candidate genes for crop breeding.

Growth and morphology responses to narrow-band blue light and its co-action with low-level UVB or green light: A comparison with red light in four microgreen species

To explore the action mode of blue light on plant elongation growth, the growth and morphology traits of arugula (Brassica eruca L., ‘Rocket’), cabbage (Brassica oleracea, unknown variety name), mustard (Brassica juncea, ‘Ruby Streaks’), and kale (Brassica napus, ‘Red Russian’) microgreens were compared under four light quality treatments: (1) R, narrow-band red light (660 nm); (2) B, narrow-band blue light (455 nm); (3) BU, broad-band blue light created by mixing B with a low level (≈ 0.7 μmol m−2 s−1) of UVB (310 nm); and (4) BG, broad-band blue light created by mixing B with a low level (≈ 6 %) of green light (530 nm). Continuous (24 -h) light-emitting diode lighting with 100 μmol m−2 s−1 photosynthetic photon flux density was used in the above treatments at ≈ 22 °C. After 7–8 days of light treatment, B, compared to R, had promoted elongation growth (i.e., longer hypocotyls or petioles, faster stem extension), and induced some other typical shade-avoidance responses (e.g., smaller cotyledons, lighter plant color, or greater biomass allocation to stem), which was associated with longer cells in the hypocotyls and lower cell density in the cotyledons except for mustard. Compared with B, the elongation growth was inhibited under BU for arugula and kale, but was promoted under BG for all the species except arugula. If considering all the plant traits together, BU and BG effect was similar to B, but different from R. Therefore, narrow-band blue vs. red light can promote elongation growth as a shade-avoidance response at both plant and cell levels, and adding low-level UVB or green light can only slightly change the narrow-band-blue-light-promoted shade-avoidance response, despite varying sensitivity among species.

Metabolic Alterations in the Enoyl-CoA Hydratase 2 Mutant Disrupt Peroxisomal Pathways in Seedlings.

Mobilization of seed storage compounds, such as starch and oil, is required to provide energy and metabolic building blocks during seedling development. Over 50% of fatty acids in Arabidopsis (Arabidopsis thaliana) seed oil have a cis-double bond on an even-numbered carbon. Degradation of these substrates requires peroxisomal fatty acid β-oxidation plus additional enzyme activities. Such auxiliary enzymes, including the enoyl-CoA hydratase ECH2, convert (R)-3-hydroxyacyl-CoA intermediates to the core β-oxidation substrate (S)-3-hydroxyacyl-CoA. ECH2 was suggested to function in the peroxisomal conversion of indole-3-butyric acid (IBA) to indole-3-acetic acid, because ech2 seedlings have altered IBA responses. The underlying mechanism connecting ECH2 activity and IBA metabolism is unclear. Here, we show that ech2 seedlings have reduced root length, smaller cotyledons, and arrested pavement cell expansion. At the cellular level, reduced oil body mobilization and enlarged peroxisomes suggest compromised β-oxidation. ech2 seedlings accumulate 3-hydroxyoctenoate (C8:1-OH) and 3-hydroxyoctanoate (C8:0-OH), putative hydrolysis products of catabolic intermediates for α-linolenic acid and linoleic acid, respectively. Wild-type seedlings treated with 3-hydroxyoctanoate have ech2-like growth defects and altered IBA responses. ech2 phenotypes are not rescued by Suc or auxin application. However, ech2 phenotypes are suppressed in combination with the core β-oxidation mutants mfp2 or ped1, and ech2 mfp2 seedlings accumulate less C8:1-OH and C8:0-OH than ech2 seedlings. These results indicate that ech2 phenotypes require efficient core β-oxidation. Our findings suggest that low ECH2 activity causes metabolic alterations through a toxic effect of the accumulating intermediates. These effects manifest in altered lipid metabolism and IBA responses leading to disrupted seedling development.

Biometric analysis of cotyledon leaves in castorbean sprouts

The growth of seedlings in the initial stages depends largely on the development and functioning of cotyledon leaves. They absorb carbon dioxide and carry photosynthesis until the first true leaf appears. This indicates the importance of this body in the life of plants and the need for its study. As for ricinus, in existing literature, symptoms of cotyledon leaves are often not mentioned at all. This work is intended to improve the morphological description of castor oil by studying the features of cotyledon leaves in seedlings. Measles of cotyledon leaves in the samples under study were carried out 8-10 days after the emergence of stairs. Given the length of the cotyledon leaves, the width and distance from the base to the widest place. For characterization of the form, the ratio of leaf width and distance to the widest part was calculated to its length. The performed studies showed that the available samples differ both in size and in the form of cotyledon leaves. Their length varied from 32.7 to 64.8 mm, width - 21.7 - 50.3 mm, the distance from the base to the widest space - 11.0 - 32.4 mm. It is established that with an increase in the overall dimensions there is a decrease in the relative width and displacement of the widest space from the base of the leaf to its middle. It is also established that the length of cotyledon leaves of the seedlings positively correlates with the length of the seeds. The correlation coefficient is 0.70. With an increase in the length of the cotyledon leaves increases their linear width, but decreases relative, that is, in the form they appear to be narrower. The correlation coefficient for these features is 0.79. Other regularities are observed from the distance to the widest place - there is an increase not only in absolute sizes (the correlation coefficient is 0.82), but also relative, though not so noticeable (the correlation coefficient is 0.18). In general, for oviposition is characteristic ovoid form of cotyledon leaves, the widest point of which is located a little closer to the base, at a distance of about 40-45% of their length. The given data show that among the rooms of our collection, which belong to the Persian and weed-field subspecies, plants with small cotyledon leaves are dominant. For the most part, these are forms in which its length is 35 - 45 mm. In common, Indian and Chinese subspecies more often found cotyledon leaves - 45 - 50 mm in length. In general, for samples of the usual subspecies it is possible to consider the typical length of cotyledon leaves from 45 to 60 mm. The largest size of this organ belongs to plants belonging to Zanzibar subspecies, although, given the small number of specimens in the collection, it can not be argued whether this is typical for a subspecies at all. In general, according to the species, the largest number of samples has mid-sized mid-sized cotton sheets. Among the 224 collection samples, 25.9% of the total number reached 45-50 mm, 21.0% - 40-45 mm and 19.2% - 50-55 mm. The remaining dimensional quantities were represented by fewer samples. The obtained data are in good agreement with the average seed sizes obtained for samples of our collection. The largest seeds are typical of specimens belonging to the common subspecies (13.4 mm), weed-field and Persian are small seeds (11.2 mm and 11.5 mm, respectively), and the other subspecies occupy an intermediate position for this indicator: in Zanzibar - 12.0 mm, in Chinese - 12.6 mm, in the Indian - 12.8 mm. Sometimes between the seeds and cotyledonous leaves can be noted similarity not only in changing the size, but even the shape. For example, the sample K-1047 has not only the narrowest cotyledons, but also the smallest seeds, the width of which is usually only 47.5% of the length. The obtained data show that morphological characteristics (size and shape) of cotyledon leaves of castor oil can serve as systematic features. It is shown that with an increase in the length of cotyledon leaves increases their linear width, while the relative, on the contrary, decreases. Also, there is an increase in the distance to their widest space. The change in the length of cotyledon leaves is proportional to the change in the length of the seeds. There is a direct correlation between their length and the size of the seeds of the corresponding specimens.

Dependence of the South African geophyte Boweia volubilis on its inflorescence for plant carbon gain

The largest organ of the eastern South African geophyte Boweia volubilis (climbing or sea onion) is the green inflorescence; leaves are small, ephemeral, and only occasionally produced. The reticulated inflorescence is also succulent. The goals of this study were to determine if the inflorescence of this plant is its sole source of energy and carbon, and if the inflorescence is capable of CAM photosynthesis. CO2 exchange of all plant organs was measured and, using their total biomass, used to calculate their contribution to the carbon budget of the whole plant. Diel fluctuations in tissue acidity were also measured in the organs.The large, green inflorescence of B. volubilis accounts for nearly two-thirds of the total biomass of the plant, while its occasional, linear leaves are small and ephemeral. The dominance of the inflorescence in the plant's biomass, coupled with its relatively high photosynthetic rate, illustrates the reliance of this plant on its inflorescence for nearly all its carbon gain. Although the upper part of the plant bulb is green, it cannot photosynthesize (no daytime CO2 uptake and no O2 release) and, thus, does not contribute to plant carbon gain. The small cotyledon and the succulent inflorescence undergo CAM-cycling, which may benefit the plant when drought-stressed.

Sucrose supplementation suppressed the growth inhibition in polyhydroxyalkanoate-producing plants.

Polyhydroxyalkanoate (PHA) is a thermoplastic polymer with several advantageous properties, including biomass origin, biocompatibility, and biodegradability. PHA is synthesized in transgenic plants harboring 3 enzymatic genes: phaA, phaB, and phaC (collectively referred to as phaABC). PHA-producing plants exhibit severe growth inhibition that leads to extremely low PHA accumulation when these enzymes are localized in the cytosol. This growth inhibition could be attributed to the deleterious effects of the PHA biosynthetic pathway on endogenous essential metabolites or to PHA cytotoxicity itself. We performed precise morphological observations of phaABC-overexpressing Arabidopsis (ABC-ox), which displayed typical growth inhibition. On growth medium without sucrose, ABC-ox exhibited a pale green phenotype, dwarfism, including small cotyledons and true leaves, and short roots. ABC-ox partially recovered from this growth inhibition when the growth medium was supplemented with 1% sucrose. This recovery was reversed after ABC-ox grown on 1% sucrose medium was transferred to soil. ABC-ox grown on 1% sucrose medium not only demonstrated recovery from growth inhibition but were also the only examined plants with PHA accumulation, suggesting that growth inhibition was not caused by PHA cytotoxicity but rather by a lack of essential metabolites.

Morphological characteristics of foetal membranes of swamp buffaloes of Assam

The present investigation was undertaken to study the morphological characteristics of foetal membrane of swamp buffaloes of Assam. Animals were calved normally and no cases of retention of placenta were recorded. The average expulsion time, weight, length, width and number of cotyledons of foetal membranes were 241.20+ 22.05 minutes, 3.47+0.12 kg, 171.87+2.99 cm, 30.83+ 0.73 cm and 114.83+ 5.56 respectively. A highly significant (P&lt;0.01) positive correlation between birth weight of the calf and weight and width of the foetal membranes and a significant (P&lt;0.05) positive correlation between birth weight and number of small cotyledons of foetal membranes were recorded in the present study. There was no significant effect of parity on various characteristics of foetal membranes except the number of large cotyledons. The number of large cotyledons was significantly (P&lt;0.05) higher in animals of third to fifth lactation than in animals of first and second lactation. The sex of calves had no significant effect on various characteristics of foetal membranes.

Importance of epidermal clocks for regulation of hypocotyl elongation through PIF4 and IAA29

Circadian clocks adjust an organism's environmentally relevant physiological responses.. In plants, a decentralized circadian clock system has recently been proposed. Epidermal clock function is crucial for cell elongation; thus, epidermis-specific overexpression of CCA1 caused smaller cotyledons and longer hypocotyls under 27°C, concomitant with elevated night time levels of PIF4 mRNA. However, which tissue's clock regulates PIF4 expression is still an open question. Here we tested spatial expression patterns of PIF4 and its downstream target IAA29 with or without epidermal clock perturbation. Using an epidermal-specific expression system, we revealed that epidermal clock perturbation increases PIF4 expression in both epidermis and mesophyll. However, IAA29 expression is mainly regulated in the epidermis, implying the potential importance of epidermis for regulation of cell elongation through PIF4 and IAA29. We conclude that the circadian clock in epidermis regulates cell elongation mainly in epidermis, and there is also another inter-tissue signaling pathway from epidermis to mesophyll.

Three SAUR proteins SAUR76, SAUR77 and SAUR78 promote plant growth in Arabidopsis.

Ethylene perceived by a family of five receptors regulates many developmental processes in Arabidopsis. Here we conducted the yeast two-hybrid assay to screen for additional unidentified proteins that interact with subfamily II ethylene receptor ETR2. Three SAUR proteins, named SAUR76, 77 and 78, were identified to associate with both ETR2 and EIN4 in different assays. Interaction of SAUR76 and SAUR78 with ETR2 was further verified by co-immunoprecipitation and bimolecular fluorescence complementation (BiFC) assays. Expressions of SAUR76-78 are induced by auxin and ethylene treatments. Compared with wild type, SAUR-overexpressing plants exhibit reduced ethylene sensitivity, while SAUR-RNAi lines exhibit enhanced ethylene sensitivity. Overexpressing the three SAURs partially complements the phenotype of subfamily II ethylene receptor loss-of-function double mutant etr2-3ein4-4, which has increased ethylene response and small cotyledon and rosette. saur76 mutation partially suppresses the reduced ethylene sensitivity of etr2-2. SAUR76/78 proteins are regulated by 26S proteasome system and larger tag increases their protein stability. These findings suggest that SAUR76-78 may affect ethylene receptor signaling and promote plant growth in Arabidopsis.

Usage of DNases and NDP kinases as qualitative markers to discriminate apomictic embryos of Poncirus trifoliata L. and Citrus aurantium L. rootstocks

The aim of the present work was to study the qualitative changes of DNases and NDP kinases of Poncirus trifoliata L. and Citrus aurantium L. rootstocks between apomictic pairs of cotyledons of different developmental stage (large and smaller pair) in mature seeds. In nucleolytic analysis of P. trifoliata, differences were observed between large and small pairs of cotyledons. Specifically, in small pairs two DNase isoforms were formed, while in the large pairs, an additional isoform appeared. In C. aurantium, four DNase isoforms were present. The first isoform appeared in all treatments, and the three other isoforms only in large pair extracts. In both P. trifoliata and C. aurantium SDS-PAGE, large pair of cotyledons showed peptide bands more intense compared to pairs of small cotyledons. When cotyledonary extract was incubated in the presence of different metals, different number and intensity of peptide bands was appeared. From TLC autoradiography, it was found that all phosphorylated bands were catalytic subunits of NDP kinases, but showed different specificity towards substrates (phosphorylated NDPs). DNases and NDP kinase activity depend on the developmental stage of nucellar embryos’ cotyledons of P. trifoliata and C. aurantium and they could be used as an efficient and precise scientific method for indicating it.

Induction of somatic embryogenesis in explants of shoot cultures established from adult Eucalyptus globulus and E. saligna × E. maidenii trees.

A reproducible procedure for induction of somatic embryogenesis (SE) from adult trees of Eucalyptus globulus Labill. and the hybrid E. saligna Smith × E. maidenii has been developed for the first time. Somatic embryos were obtained from both shoot apex and leaf explants of all three genotypes evaluated, although embryogenic frequencies were significantly influenced by the species/genotype, auxin and explant type. Picloram was more efficient for somatic embryo induction than naphthaleneacetic acid (NAA), with the highest frequency of induction being obtained in Murashige and Skoog medium containing 40 µM picloram and 40 mg l(-1) gum Arabic, in which 64% of the shoot apex explants and 68.8% of the leaf explants yielded somatic embryos. The embryogenic response of the hybrid was higher than that of the E. globulus, especially when NAA was used. The cultures initiated on picloram-containing medium consisted of nodular embryogenic structures surrounded by a mucilaginous coating layer that emerged from a watery callus developed from the initial explants. Cotyledonary somatic embryos were differentiated after subculture of these nodular embryogenic structures on a medium lacking plant growth regulators. Histological analysis confirmed the bipolar organization of the somatic embryos, with shoot and root meristems and closed procambial tissue that bifurcated into small cotyledons. The root pole was more differentiated than the shoot pole, which appeared to be formed by a few meristematic layers. Maintenance of the embryogenic lines by secondary SE was attained by subculturing individual cotyledonary embryos or small clusters of globular and torpedo embryos on medium with 16.11 µM NAA at 4- to 5-week intervals. Somatic embryos converted into plantlets after being transferred to liquid germination medium although plant regeneration remained poor.

The contribution of seeds to the recruitment of a Nymphoides peltata population

The Nymphoides peltata population expands quickly in Lake Taihu, China. One question addressed in this study is whether the seeds of N. peltata contribute to this expansion. The buoyancy and germination of N. peltata seeds and the development of N. peltata seedlings were studied, using seeds collected from Lake Taihu. The results indicated that a low wind velocity of 2.4–3.0 m s −1 had a slightly negative effect on seed buoyancy. After 19 and 67 h of gentle stirring, 50% and 90%, respectively, of the N. peltata seeds had sunk. Few seeds floated again after sinking, but these refloating seeds sank soon with the disturbance. The N. peltata seeds did not germinate without stratification, but the stratification of seeds for a two-week period resulted in a high germination rate (63.3%) at a light intensity of 20 μmol photons m −2 s −1 . Both the light and stratification treatments stimulated the seeds germination. The seeds did not germinate in sediment at depths greater than 0.25 cm. A high germination rate (74%) was observed for the seeds that laid on the water–sediment interface; however, nearly all of the germinated seeds floated on the water surface after germination. Only a small fraction (14%) of the buoyant seedlings could re-establish in shallow water (less than 3 cm). In the eighth week of the experiments, the buoyant seedlings that failed to re-establish rotted. When grown in low light intensity conditions, the N. peltata seedlings had smaller cotyledons, shorter primary roots, and weak development of adventitious roots. Sufficient light was important for both seed germination and seedling development. It was found that sexual reproduction is likely to have little direct contribution to the rapid expansion of N. peltata towards the centre of this large shallow lake.

ABA inhibits entry into stomatal‐lineage development in Arabidopsis leaves

The number and density of stomata are controlled by endogenous and environmental factors. Despite recent advances in our understanding of stomatal development, mechanisms which prevent stomatal-lineage entry remain unclear. Here, we propose that abscisic acid (ABA), a phytohormone known to induce stomatal closure, limits initiation of stomatal development and induces enlargement of pavement cells in Arabidopsis cotyledons. An ABA-deficient aba2-2 mutant had an increased number/proportion of stomata within a smaller cotyledon, as well as reduced expansion of pavement cells. This tendency was reversed after ABA application or in an ABA over-accumulating cyp707a1cyp707a3 doublemutant. Our time course analysis revealed that aba2-2 shows prolonged formation of meristemoids and guard mother cells, both precursors of stoma. This finding is in accordance with prolonged gene expression of SPCH and MUTE, master regulators for stomatal formation, indicating that ABA acts upstream of these genes. Only aba2-2 mute, but not aba2-2 spch double mutant showed additive phenotypes and displayed inhibition of pavement cell enlargement with increased meristemoid number, indicating that ABA action on pavement cell expansion requires the presence of stomatal-lineage cells.

Focal Placenta Accreta and Spontaneous Uterus Rupture in the Post-Partum

Introduction: Uterine rupture occurs when the integrity of the myometrial wall is compromised. It could interest the uterine body (prior to labour) or the lower segment (during labour). The main causes of uterine rupture are obstetric anamnestic factors and/or the administration of oxytocin. Case presentation:The authors report the case of a 42 years old patient without risk factors for uterine rupture. After the expulsion of the placenta the mother had continuous blood loss, for this reason she was subjected to subtotal hysterectomy. Histological examination revealed the absence of decidua in the uterine fundus and thinning of the myometrium. Histological examination of the lesion at the site commented that there was infiltration of the chorionic villi into the endometrium and this is undoubtedly the features of placenta accreta. Conclusion: The authors emphasize the importance of careful observation of the placenta after delivery for the absence of even small placental cotyledons in order to eliminate a rare risk factor for silent uterine rupture.