Sucrose, raffinose and stachyose accumulate in soybean [Glycine max L. (Merrill)] embryos during seed maturation. To determine the relationship of plant maternal composition on seed composition, soluble carbohydrates in three 1-cm2 leaf punches at three plant growth stages (R2, R3, R6) and in seed coat cup exudates in planta were analysed at four 30-min intervals on soybean plants (R5) with low-raffinose, low-stachyose (LRS) seeds expressing the mutant stc1 phenotype; low-raffinose, low-stachyose and low-phytin (LRSP1, LRSP2) seeds expressing the mutant mips phenotype; or normal raffinose, stachyose and phytin (CHECK) seeds expressing the Stc1 and Mips phenotype. Leaf sucrose (23.6 μg cm− 2), myo-inositol (9.3 μg cm− 2), d-chiro-inositol (6.7 μg cm− 2), d-ononitol (0.76 μg cm− 2), d-pinitol (50.1 μg cm− 2) and total soluble carbohydrates (107.1 μg cm− 2) were not significantly different between phenotypes. d-chiro-Inositol, myo-inositol, d-pinitol and sucrose were unloaded from soybean seed coat cups in planta at decreasing rates over the four sequential periods of sampling. Unloading rates of sucrose and myo-inositol were highest for LRS, d-pinitol was highest for LRSP2, and d-chiro-inositol was not different between LRS, LRSP1, LRSP2 and CHECK. Free cyclitols were 60% of total soluble carbohydrates in leaves and 20% in seed coat cup exudates. Except for sucrose and d-pinitol, seed phenotype had little influence on the composition of compounds unloaded from seed coats to maturing embryos of low-raffinose, low-stachyose seeds. Maternally supplied cyclitols may contribute, in part, to changes in the composition of cyclitol galactosides stored in mature seeds.

A protein named QP47 has been purified from quiescent nuclei of root meristems of Pisum sativum, and used to prepare a polyclonal antibody. Immunolocalization of this protein with fluorescent probes revealed a nuclear distribution of thread-like structures. However, the relationship between the distribution of QP47 immunofluorescence and the structural organization of the chromatin required further investigation. The decrease in content of this protein in the nuclei of embryo cells seems to be correlated with the transition from quiescence to proliferation. QP47 degradation seems to depend upon an increase in the state of its phosphorylation. This protein is not present in normally proliferating cells, or in cells whose cell proliferation has been arrested by starvation or differentiation. It is hypothesized that QP47 may be required specifically during the quiescent period for specific structural organization of the chromatin.

Fruits of Melastomataceae constitute a key resource for Neotropical frugivores. However, the mechanisms determining gut-passage effects on seed germination are poorly known. Here, we determine how bird gut-passage affects seed germination in three species of Miconieae by running germination experiments, examining changes in seed coat structure and determining germination inhibition by fruit extracts. Mature fruits of Clidemia urceolata, Leandra aurea and Miconia rubiginosa were sampled in south-eastern Brazil and seeds were submitted to treatments evaluating gut-passage effects and different concentrations of fruit extracts. Light and scanning electron microscopy were used to compare seed coat structure and thickness of control and gut-passed seeds. We found minor effects of gut passage on seed germination. However, changes in seed coat structure of gut-passed seeds of L. aurea may have been related to a decrease in germination. Our data also support the idea that germination inhibitors in fruit pulp may contribute to the inhibition effect. Our study corroborates the idea that changes in the seed coat following gut passage modulate the complex fruit–frugivore interactions, especially between plants and generalist dispersers, and that seed cleaning is a key factor determining seedling establishment in Neotropical Melastomataceae.

At the time of protrusion, radicles of lettuce seeds became susceptible to desiccation damage. Concomitant with radicle elongation, both the reducing sugar content and the amount of lipid-aldehydes increased. The role of the hydroxy- and lipid-aldehydes in browning reactions that occurred during desiccation and re-imbibition was analysed. It was concluded that both types of aldehydes reacted with amino-groups during desiccation and that the increase in lipid-aldehydes during germination could be due to the augmented reducing sugar content. Therefore, the high reducing sugar content in radicles of germinated lettuce seeds may be the primary source of hydroxyl radicals, and thereby, a principal cause of desiccation damage.

Successful remobilization of seed reserves is the driving force behind seedling establishment for maximum final crop outcomes. The remobilization of stored maize seed phosphorus (P), and its allocation towards growing seedlings is critical for P-autotrophy during early ontogeny. We aimed to (1) evaluate the time frame of the origin of P utilized by maize seedlings, including the heterotrophic, transitional and autotrophic phases; and (2) compare P and carbon (C) dynamics in both seed and seedling compartments during the same phases. Using isotopic signatures (32P), we identified different P fluxes (P-heterotrophy, P-transition and P-autotrophy) and determined the proportion of P fluxes from heterotrophic seed P and external P uptake during 23 d of early ontogeny. The P-heterotrophic growth phase lasted from the first to the fourth day after sowing, when seedlings were entirely made up of heterotrophic P originating from remobilized seed P pool. In our experimental conditions, the P-transitional phase, when growing seedlings were supported by both heterotrophic and autotrophic P, lasted from the fifth to the fifteenth day after sowing. Thereafter, seed P reserves were exhausted and seedlings depended entirely on external P uptake, indicating the P-autotrophic stage. Although seed P reserves were remobilized earlier than C reserves, the length of the three growth phases for P and C was similar in the maize seedlings.

The prediction of seed longevity (P50) is traditionally performed by the use of the Probit model. However, due to the fact that the survival data are of binary origin (0,1), the fit of the model can be compromised by the non-normality of the residues. Consequently, this leads to prediction losses, despite the data being partially smoothed by Probit and Logit models. A possibility to reduce the effect of non-normality of the data would be to apply the principles of the central limit theorem, which states that non-normal residues tend to be normal as the n sample is increased. The Logit and Probit models differ in their normal and logistic distribution. Therefore, we developed a new estimation procedure by using a small increase of the n sample and tested it in the Probit and Logit functions to improve the prediction of P50. The results showed that the calculation of P50 by increasing the n samples from 4 to 6 replicates improved the index of correctness of the prediction. The Logit model presented better performance when compared with the Probit model, indicating that the estimation of P50 is more adequate when the adjustment of the data is performed by the Logit function.

Due to shared geological history and proximity, the flora of New Caledonia is closely linked to other Gondwanan land fragments such as Australia and New Zealand. Many predominant Australian groups are well represented within the New Caledonian flora, including the genera Hibbertia (23 species) and Scaevola (10 species). Previous studies have found that these two genera in particular have a marked positive germination response to smoke products, although all previous studies have centred on Australian species from fire-prone environments. In this present study, we test the hypothesis that two New Caledonian species of Hibbertia and Scaevola are smoke responsive even though the climate and ecological drivers in New Caledonia are in many respects fundamentally different from those of most of Australia. Preliminary results showed that germination of Hibbertia pancheri was significantly accelerated in response to smoke water while germination in Scaevola montana was also significantly enhanced. To the best of our knowledge, this is the first time that these trends have been illustrated for any New Caledonian species and these results will enhance restoration efforts of ultramafic scrublands impacted by mining activities in New Caledonia.

The role of abscisic acid (ABA) in seed germination of two cultivars of lettuce (Lactuca sativa L.; light-sensitive Ritsa and light-insensitive Strada) was investigated. The inhibition of Ritsa seed germination by exogenous ABA was higher than that of Strada seeds, the extent of inhibition of both cultivars being reduced by a short light break. At 25°C the sensitivity of both cultivars to exogenous ABA was higher than at 15°C. The endogenous level of ABA was similar in dry seeds of both cultivars, increasing temporarily in Ritsa seeds during the first 4 h of imbibition in darkness but not in Strada seeds, nor in Ritsa seeds exposed to a short light break. The transitory increase of ABA content in Ritsa seeds imbibed in darkness was accompanied by increased expression of the gene responsive to ABA (Rab) under these conditions. Zorial (Norflurazone), an ABA-biosynthesis inhibitor, decreased ABA content and allowed dark germination of the light-requiring Ritsa seeds. A short light break induced germination of Ritsa seeds when applied at 24 and 48 h after imbibition onset, i.e. after the transitory increase of ABA. GA3, on the other hand was effective when applied at the beginning of imbibition. It seems that light induces germination of the photoblastic Ritsa seeds by both inhibiting ABA synthesis and decreasing seed sensitivity to ABA and inhibitory processes induced by it.

DNA polymerase 2 holoenzyme is an α-type polymerase present as a major activity in 24-h germinated maize embryo axes. At this time, several of the polypeptides that compose this multisubunit enzyme are phosphorylated. During the germination of artificially deteriorated maize embryo axes, total DNA polymerase activity decreases by around 50% when compared with activity in non-deteriorated axes. DNA polymerase 2 appears to be damaged by the deterioration treatment, greatly reducing its activity. This decrease in activity is related to protein degradation during germination since the amount of both the holoenzyme and the different polymerase 2 subunits is reduced as imbibition progresses. The decrease in amount is more dramatic for some of the subunits than for others, i.e., the amount of the 90-kDa catalytic subunit is reduced by about half, whereas all other subunits totally disappear at different times during germination. The phosphorylation state of the different polypeptides is also greatly affected.

Observing the embryo in dust-like seeds with a rigid coat presents a particular challenge, because it is not possible to use conventional techniques applied to normal-sized seeds. A new combination of softening and clearing techniques, which is remarkably effective for direct observations of embryos in minute seeds, is reported here. Moreover, no special seed treatment is required prior to application of this combination of techniques, and good results are obtained from living and preserved material. Dust-like seeds of Cytinus hypocistis and Cytinus ruber with a rigid coat were treated successively with Franklin's and with Jeffrey's softening fluids, and then with Herr's clearing fluid. The combined action of the two softening fluids caused sufficient seed coat rupture to allow Herr's fluid to clear seed tissues, permitting effective observation of the embryo. This technique should be applicable to a wide range of species with dust-like seeds, and its possibilities for biological studies are numerous.

Mediterranean characteristics are attributed to the genus Crocus, which is inadequately studied in terms of seed germination. An afterripening requirement is very common in environments with warm and dry periods, and photoinhibition has been detected in many angiosperms inhabiting dry and open areas. The effects of afterripening and light on seed germination were investigated for the first time in 23 native Greek Crocus taxa, collected from various localities with either a Mediterranean or a temperate climate. Germination experiments were conducted in continuous darkness and in light at the optimal temperature for each taxon, with both freshly collected and afterripened seeds; warm stratification (20°C, darkness) was also examined in 22 taxa. A number of selected taxa were additionally investigated with respect to afterripening outdoors, afterripening and warm stratification at higher temperatures (35 and 25°C, respectively), stratification at 20/10°C, dry storage at low temperatures, response to gibberellic acid and phenology of embryo growth. It was postulated that an afterripening requirement is a characteristic of the genus Crocus, and we found that it can be fulfilled in nature during the Mediterranean dry summer. Also, for the vast majority of the taxa, warm stratification and stratification at 20/10°C can both meet the afterripening requirement. Embryos of the taxa studied are underdeveloped and have to grow prior to germination. Intrageneric differences of seed germination were observed only towards light, with photoinhibition being predominant in taxa from drier environments.

Detecting the presence of genetically modified plants (adventitious presence of unwanted transgenic plants, AP) from outcrossing species such as maize requires a method that lowers laboratory costs without losing precision. Group testing is a procedure in which groups that contain several units (plants) are analysed without having to inspect individual plants, with the purpose of estimating the prevalence of AP in a population at a low cost without losing precision. When pool (group) testing is used to estimate the prevalence of AP (p), there are sampling procedures for calculating a confidence interval (CI); however, they usually do not ensure precision in the estimation of p. This research proposes a method to determine the number of pools (g), given a pool size (k), that ensures precision in the estimated proportion of AP (that is, it ensures a narrow CI). In addition, the study computes the maximum likelihood estimator of p under pool testing and its exact CI, considering the detection limit of the laboratory, d, and the concentration of AP per unit (c). The proposed sample procedure involves two steps: (1) obtain a sample size that guarantees that the mean width of the CI () is narrower than the desired width (ω); and (2) iteratively increase the sample size until is smaller than the desired width (ω) with a specified degree of certainty (γ). Simulated data were created and tables are presented showing the different possible scenarios that a researcher may encounter. An R program is given and explained that will reproduce the results and make it easy for the researcher to create other scenarios.

The seed consists of three distinct regions, the zygotic embryo and endosperm and the maternal seed coat. Development of the seed requires co-ordinated growth and differentiation within each of these regions. Although the major events that occur during seed development have been studied extensively at the anatomical, physiological and molecular level, a comprehensive understanding of gene activity in each seed region has been lacking. DNA microarrays and extensive sequencing of cDNA libraries permit genome-wide analyses of mRNA populations of biological samples. We review recent studies of genome-wide gene activity that illustrate approaches used to provide new insights into the processes that occur during seed development.

Fourteen seedlots of five species of Rhus were surveyed for presence/absence of physiological dormancy and/or for germination requirements of non-dormant seeds. Physiological dormancy was present in the four seedlots of R. aromatica studied, but not in either of the two seedlots of its close relative R. trilobata, which is in contrast to previous reports. Neither were seeds of R. glabra, R. typhina, nor R. virens physiologically dormant. Stratification at 5oC for 1 week or incubation in 500 or 1000 mg/l solutions of gibberellic acid broke physiological dormancy in > 90% of the R. aromaticaseeds. Maturation desiccation acted as a switch from a developmental to a germinative mode in R. aromatica embryos, whereas it was not required for germination of R. glabra or R. virens (R. trilobata and R. typhinanot tested). Seeds of all five species incubated on a moist substrate became fully imbibed in 2 d, at which time moisture content was approx. 70–80%of their initial weight. In general, germination of non-dormant seeds was rather insensitive to temperature and light. Seeds germinated equally well in light and in darkness over a daily (12 h/12 h) temperature range of 15/6–35/20oC. Over a 4 week period, the best germination percentages were obtained at 25/15 and 20/10oC, whereas 35/20oC appeared to be supraoptimal, though not always significantly so. If the incubation period was extended to 30 weeks, germination percentages were as high at 15/6oC as at 25/15 and 20/10oC.

Low and high moisture kernels and embryos were imbibed by soaking in distilled water at 5°C and 25°C. Leaching of seeds and embryos was measured by ion conductivity of imbibition water after fixed time intervals. Imbibed kernels were placed on moist filter paper after 1 h imbibition and embryos on a solid culture medium after 15 min imbibition and germinated at 25°C. Primary root length was measured 3 days after germination.

The leakage from seeds or embryos was correlated with the velocity of water uptake but did not show its highest values when low moisture seeds or embryos were imbibed at chilling temperature. Furthermore germination was apparently not affected by imbibitional chilling of either low moisture content seeds or embryos. In one of the three genotypes tested (B73) seedlings from low moisture content seeds imbibed at 5°C showed a reduction of the primary root growth. However, this reduction was also seen in seedlings from low moisture B73 seeds imbided at 25°C and resulting in higher level of leaching. Thus, injury by imbibition of low moisture seeds appears independent of chilling temperature and not due to loss of semipermeability of membrane lipids. Our results suggest that, in the case of embryos, water inrush into the cells reaches levels injurious for membrane integrity independently of the two moisture contents and temperature considered.

Feeding stem–leaf–pod explants with d-chiro-inositol and d-pinitol was used as a method to modify α-d-galactosides in developing pea (Pisum sativum) seeds. Four genotypes differing in the composition of raffinose, stachyose and verbascose (raffinose family oligosaccharides or RFOs) in seeds – high RFOs (cv. Tiny), low RFOs (SZD175) and low verbascose (cv. Hubal and cv. Wt 506) – were studied. Although seeds of all examined pea lines were able to take up both d-chiro-inositol and d-pinitol, only d-chiro-inositol was effectively converted into its galactosides: mainly fagopyritol B1 (O-α-d-galactopyranosyl-(1 → 2)-d-chiro-inositol) and fagopyritol B2 (O-α-d-galactopyranosyl-(1 → 6)-O-α-d-galactopyranosyl-(1 → 2)-d-chiro-inositol). In seeds of pea lines naturally containing low levels of verbascose (cv. Hubal) and low RFOs (SZD175), the enhanced accumulation of fagopyritols depressed the RFO level by c. 64 and 20%, respectively. Moreover, in both genotypes, about 25 and 30% of total galactose bound in α-d-galactosides occurred in fagopyritols. d-Pinitol present in the pea seeds was converted into monogalactosides, but their accumulation was several-fold lower than that of fagopyritols and did not significantly influence the accumulation of RFOs. Pea seeds with the composition of soluble carbohydrates modified by feeding with either of the cyclitols were able to complete germination.

Leymus Racemosus, The Mammoth Wild Rye, Is A Rhizomatous Perennial Grass, Mainly Distributed In The Moving Or Semi-Stabilized Sand Dunes In Deserts Of The Junggar Basin In Xinjiang, China. The Revival Ability Of The Young Seedling After Periods Of Desiccation Can Be Influenced By Several Factors: (1) The Stage Of Seedling Development – The Later The Stage At Dehydration, The Longer The Root Length And The Lower Is The Percentage Of Seedlings That Survive; (2) The Length Of The Period Of Desiccation – The Longer The Period That The Seedlings Are Under Desiccation, The Lower Is The Percentage Of Seedlings That Survive; (3) Endosperm Size – The Smaller The Proportion Of Endosperm That Remains In The Caryopses, The Lower Is The Percentage Of Seedlings That Revive, Determined By (A) The Stage Of Seedling Development, And (B) The Proportion Of The Endosperm That Is Removed By Cutting; And (4) Caryopsis Size – The Larger The Polymorphic Caryopses, The Higher Is The Percentage Of Young Seedlings That Revive From Periods Of Desiccation. The Physiological And Ecological Implications Of L. Racemosus Seedling Desiccation Tolerance Are That Under Extreme Desert And Unpredictable Environmental Conditions, The Chances Of Seedling Establishment Are Increased.

Orchid seeds are among the smallest seeds in nature and they are naturally rich in fatty acids. However, the fatty acid composition of orchid seeds has not been investigated because the sample masses utilized for widely used methods for fatty acid profiling would generally require prohibitively large numbers (i.e. 10,000s) of seeds. The present work aimed to develop a method for fatty acid analysis using gas chromatography–mass spectrometry on small quantities (mg) of seeds. The method was developed using the seeds of two species, Dactylorhiza fuchsii, a temperate terrestrial, and Grammatophyllum speciosum, a tropical epiphyte. A range of sample masses was tested to determine the minimum mass required to achieve reliable fatty acid composition data. A direct transesterification method was used, which did not require extraction of fatty acids from seeds prior to analysis, and the effects of seed processing (crushed versus intact seeds) and incubation time in toluene on fatty acid yield were tested. Stable fatty acid profiles were obtained using as little as 10 mg of seeds. Neither crushing the seeds nor extending the toluene incubation step had much effect on the fatty acid yield. The simple direct transesterification method presented will enable the fatty acid composition of orchid seeds, and possibly other small seeds, to be determined reliably for studies into seed development, storage and germination.

The cytoplasm of soybean seed axes is known to undergo a glass transition as moisture content decreases. In this study we have investigated whether the glass transition is reflected in the macroscopic mechanical properties of the seeds. Constant-deformation-rate compression tests and constant-deformation relaxation tests were performed with a cylindrical indenter on soybean cotyledons equilibrated to moisture contents ranging from 2% to 16% (dry basis). The apparent modulus of elasticity was found to rise sharply as moisture content declined below 10%, showing an inflection point at 9.8%, and a relatively constant elasticity below 7%. Other measures of mechanical behaviour were also constant in the drier ranges, including linear deformation, and plastic deformation. Each of these viscoelastic characteristics showed an inflection point or a departure from a linear function in the region of 7.5–9.8% moisture content, the hydration region below which the tissue is in a glassy state. It is suggested that the viscoelastic qualities of dry soybeans are principally a consequence of the tissues being in the glassy state.

Benzyladenine, a synthetic cytokinin, stimulates DNA metabolism during maize germination; apparently such stimulation occurs in two phases, and during the first phase stimulations of DNA synthesis, of protein kinase activity (both α-amanitin repressible), of DNA polymerase and poly ADP-ribosyl polymerase activities are observed. Since the evidence suggested that the effects produced by BA were due, at least partially, to transcriptional activation, attempts were made to discover genes, by subtractive hybridization of a cDNA library or by differential display, whose expression depended on the presence of BA; however these were unsuccessful. BA modulated the expression of a limited number of genes only. The possible mechanism by which BA could be promoting DNA metabolism during maize germination is discussed.