Dill seed germ development after short-term temperature stress.

NNew data on germ growth processes of dill seeds formed at the first and second branching orders after exposure to short-term heat stress (40 °C) are presented. Morphometric method and analysis of dill seed embryo growth in dynamics were used. The studies were carried out in 20152017 at the All-Russian Research Institute of Vegetable Growing, a branch of FSBSI FSCVG. Seeds of dill (Anethum graveolens L.) of the variety Centaurus from the first and second branching orders were the object of research. First, seeds were germinated in a thermostat. Then, swollen roots were exposed to a temperature of 40 °C according to the experiment scheme: 0 (control); 1; 2; 3; 4 and 5 days. After incubation, the seeds were transferred to standard conditions (temperature 20 °C) and germinated in Petri dishes on filter paper without light for 21 days. Germ size was measured using image analysis software. Critical embryo length and degree of underdevelopment were determined, and the ratio of embryo length to endosperm length (I Z/E) was calculated. Logistic regression with four parameters: b, c, d, e., was used to construct a germ growth curve. The relationship between the parameters was assessed using Pearson correlation analysis. The differences were considered statistically significant at P≤0.05. The duration of temperature action, which has an inhibitory effect on embryo growth, germination rate, the number of germinated seeds, were revealed. It was found that the embryos of seeds obtained from different branching orders have different sizes and have different intensity of growth under stress and standard conditions. It was shown that the effect of brief temperature (40 °C) on embryo growth depends on branching order and that embryos of seeds of the second branching order are more sensitive to high temperature. Morphometric parameters of the source were shown to play a critical role in the ability of dill seeds to resist the effect of temperature stressor during germination.

GROWTH OF THE CHICKEN EMBRYO AND ITS REPRODUCTIVE ORGANS

Статья посвящена анализу относительного прироста массы и длины куриного эмбриона и его репродуктивных органов. На основании полученных данных установлена асинхронность изменения изучаемых показателей. Выявлено, что прирост массы куриного эмбриона проходил с чередованием периодов увеличения и снижения темпов роста изучаемого показателя. Наиболее интенсивный прирост массы показали куриные эмбрионы в интервале эмбриогенеза 12-13 суток. Максимальный прирост массы яичника куриного эмбриона так же приходится на этот возрастной интервал. Минимальный прирост массы куриного эмбриона зафиксирован в возрастном периоде 11-12 суток и 18-19 суток. Рост длины эмбриона имеет более выровненные значения, по сравнению с ростом массы эмбриона, так как за наблюдаемый период (11-20 суток) находился в диапазоне 8-12 %, и только в интервале 19-20 суток составил лишь 3 %. Результаты исследования показали, что развитие яйцевода и яичника проходит асинхронно. Это проявляется в том, что темп прироста массы яйцевода постепенно увеличивается, а темпы прироста массы яичника, напротив, снижаются в течение эмбрионального развития. The article is devoted to the analysis of the relative increase in the mass and length of the chicken embryo and its reproductive organs. Based on the data obtained, the asynchrony of changes in the studied indicators is found. It was found that the increase in the mass of the chicken embryo took place with alternating periods of increase and decrease in the growth rate of the studied indicator. The most intensive weight increase was shown by chicken embryos in the embryogenesis interval of 12-13 days. The maximum increase in the ovarian mass of a chicken embryo also occurred in this age range. The minimum weight increase of a chicken embryo was noticed in the age period of 11-12 days and 18-19 days. The increase of the embryo length has more levelled values compared to the increase of the embryo mass, since during the observed period (11-20 days) it was in the range of 8-12 %, and only in the range of 19-20 days it was only 3 %. The results of the study showed that the developments of the oviduct and ovary are asynchronous. This is seen in the fact that the rate of oviduct mass growth gradually increases, while the rate of ovarian mass growth, on the contrary, decreases during embryonic development.

Scaling of Internal Organs during Drosophila Embryonic Development

Many species show a diverse range of sizes; for example, domestic dogs have large variation in body mass. Yet, the internal structure of the organism remains similar, i.e. the system scales to organism size. Drosophila melanogaster has been a powerful model system for exploring scaling mechanisms. In the early embryo, gene expression boundaries scale very precisely to embryo length. Later in development, the adult wings grow with remarkable symmetry and scale well with animal size. Yet, our knowledge of whether internal organs initially scale to embryo size remains largely unknown. Here, we utilise artificially small Drosophila embryos to explore how three critical internal organs - the heart, hindgut and ventral nerve cord (VNC) - adapt to changes in embryo morphology. We find that the heart scales precisely with embryo length. Intriguingly, reduction in cardiac cell length, rather than number, appears to be important in controlling heart length. The hindgut - which is the first chiral organ to form - displays scaling with embryo size under large-scale changes in the artificially smaller embryos but shows few hallmarks of scaling within wild-type size variation. Finally, the VNC only displays weak scaling behaviour; even large changes in embryo geometry result in only small shifts in VNC length. This suggests that the VNC may have an intrinsic minimal length, which is largely independent of embryo length. Overall, our work shows that internal organs can adapt to embryo size changes in Drosophila. but the extent to which they scale varies significantly between organs.

Seed germination in Narcissus yepesii (Amaryllidaceae): clinal variation in the morphophysiological dormancy levels

Seed dormancy classes determine both population and species-level processes which can be crucial in the life cycle of many plants. However, there are no studies of a dormancy cline between levels of morphophysiological dormancy (MPD). We aimed to determine the class of seed dormancy of Narcissus yepesii exhibits in order to explore links between different dormancy levels, previously characterized in two closely related phylogenetic congeners, N. alcaracensis and N. longispathus. Experiments were carried out under both near-natural temperature and controlled laboratory conditions. The parameters calculated were mean embryo length, radicle and shoot emergence percentages. The effects of different periods of storage; and different periods with or without GA3 of warm, cold or warm plus cold were analysed. The Narcissus populations from the Baetic System of mountain ranges in south-eastern Spain show clinal variation in a northeast–southwest gradient from intermediate to non-deep complex MPD, through the coexistence of intermediate and non-deep complex MPD in N. yepesii (21 % and 74 %, respectively). In addition, 54 % of stored seeds were able to show both levels of MPD. Narcissus yepesii occupies an intermediate position between N. alcaracensis and N. longispathus in the geographical distribution and in the clinal germination ranges. It strongly suggests an evolutionary gradient, which connects the intermediate complex MPD with the non-deep complex MPD in southern Iberian daffodils. This is the first study showing a gradient in the evolution between levels of MPD. Our results demonstrate a cline in these levels in response to both an environmental gradient and genetic differences.

Differential Interpretation of Mountain Temperatures by Endospermic Seeds of Three Endemic Species Impacts the Timing of In Situ Germination

Predicting seed germination in the field is a critical part of anticipating the impact of climate change on the timing of wild species regeneration. We combined thermal time and soil heat sum models of seed germination for three endemic Mediterranean mountain species with endospermic seeds and morphophysiological dormancy: Aquilegia barbaricina, Paeonia corsica, and Ribes sandalioticum. Seeds were buried in the soil within the respective collection sites, both underneath and outside the tree canopy, and their growth was assessed regularly and related to soil temperatures and estimates of the thermal characteristics of the seeds. The thermal thresholds for embryo growth and seed germination of A. barbaricina assessed in previous studies under controlled conditions were used to calculate soil heat sum accumulation of this species in the field. Thermal thresholds of seed germination for P. corsica and R. sandalioticum were not previously known and were estimated for the first time in this field study, based on findings of previous works carried out under controlled conditions. Critical embryo length and maximum germination for A. barbaricina were reached in April, and in December for R. sandalioticum. Seeds of P. corsica stay dormant in the ground until the following summer, and the critical embryo length and highest germination were detected from September to December. Soil heat sum models predicted earlier germination by one month for all three species under two Intergovernmental Panel on Climate Change (IPCC) scenarios, based on the assumption that the estimated thermal thresholds will remain constant through climate changes. This phenological shift may increase the risk of mortality for young seedlings. The models developed provide important means of connecting the micro-environmental niche for in situ seed germination and the macro-environmental parameters under a global warming scenario.

Different levels of morphophysiological seed dormancy in Ribes alpinum and R. uva-crispa (Grossulariaceae) facilitate adaptation to differentiated habitats

Aim of the study: To study the germination ecology of two species of the genus Ribes to reveal their levels of morphophysiological dormancy (MPD) and to facilitate the production of plants from seeds, a key tool for population reinforcement.Area of study: Experiments were carried out both outdoors and in the laboratory in Albacete (Spain) with seeds from the Meridional Iberian System mountain range.Material and methods: Seeds from one population of Ribes alpinum and from other of Ribes uva-crispa were collected during several years. Embryo length, radicle and seedling emergence, and effects on germination of stratification and GA3 were analysed to determine the level of MPD.Main results: In R. alpinum, embryo length in fresh seeds was 0.49 mm, needing to grow to 1.30 mm to germinate. Warm stratification (25/10ºC) promoted embryo length enlargement to 0.97 mm. Afterwards, seeds germinated within a wide temperature range. Embryo growth and seedling emergence occur late summer-early autumn. In R. uva-crispa, embryo length in fresh seeds was 0.52 mm, being 2.10 mm the minimal size to germinate. Embryos exposed to a moderately warm stratification (20/7ºC + 15/4ºC) followed by cold (5ºC) grew to 2.30 mm. Then, seeds germinated ≥ 80% when incubated at temperatures ≥ 15/4ºC. Embryos grew in autumn/early winter, and seedlings emerged late winter-early spring.Research highlights: These results showed that R. alpinum seeds have a nondeep simple MPD while R. uva-crispa seeds have a nondeep complex MPD. Moreover, the different germinative models found for each species help explain their installation in distinct habitats.Keywords: Ribes; seed dormancy break; radicle emergence; seedling emergence; nondeep simple and nondeep complex MPD.Abbreviations used: Morphophysiological dormancy (MPD), morphological dormancy (MD), Gibberellic acid (GA3), months (m).

Polymorphism of morphometric parameters of seeds common anise and cumin

Relevance. The degree of variability of the linear parameters of the morphological elements of the seeds of the anise (variety Vityaz) and cumin (variety Peresvet).Materials and methods. 1) Plants: Monarda fistulosa L. (the breeding sample №5 U.P.), Monarda citriodora Cerv. ex Lag. (Simka variety), Melissa officinalis L. (Zhemchuzhina variety). 2) secondary metabolites: flavonoid glycoside linarozid and steroid glycoside moldstim.Methods. The studies were carried out in VNIIO – a branch of the FSBSI Federal Scientific Vegetable Center. The measurement of the length of the seed and endosperm was carried out using a caliper (GOST 166-89). The embryo length was determined using a Levenhuk 670T microscope and a DCM 300 MD video eyepiece at Ч 40 magnification using Scope Photo (Image Software V. 3.1.386). The lengths of each seed, endosperm (longitudinal section) and embryo (after isolation) were sequentially analyzed. The indices IE/C, IZ/E, IZ/C were calculated as the corresponding ratios of the length of the seed, endosperm and embryo.Results. The maximum length of the seed (4.76±0.10 mm) and of the endosperm (4.08 ± 0.08 mm) and the length of the embryo (1.40±0.02 mm) were noted in cumin seeds. The average values of the coefficient of variation (V), on the contrary, were minimal for cumin seeds, varying from 7.8% for the length of the embryo to 11.5% for the length of the seed. The average values of the coefficient of variation (V) for anise varied from 9.3% for the length of the embryo to 14.7% for the length of the seed. The maximum level of variability in both cultures was noted for seed size. Correlation analysis showed that a close relationship was observed in anise (r=0.912) and cumin seeds (r=0.876) only between the length of the seed and the length of the endosperm. The value of the correlation coefficient (r) between the linear sizes of the seed and the embryo was 0.195 for anise and 0.229 for cumin seeds, and between the length of the endosperm and the length of the embryo, 0.237 and 0.214, respectively. The correlation coefficient (r) between the index IZ/E and the linear sizes of the seed, endosperm and embryo had low negative values from -0.221 to - 0.345.

The dynamic transmission of positional information in stau- mutants during Drosophila embryogenesis

It has been suggested that Staufen (Stau) is key in controlling the variability of the posterior boundary of the Hb anterior domain (xHb). However, the mechanism that underlies this control is elusive. Here, we quantified the dynamic 3D expression of segmentation genes in Drosophila embryos. With improved control of measurement errors, we show that the xHb of stau– mutants reproducibly moves posteriorly by 10% of the embryo length (EL) to the wild type (WT) position in the nuclear cycle (nc) 14, and that its variability over short time windows is comparable to that of the WT. Moreover, for stau– mutants, the upstream Bicoid (Bcd) gradients show equivalent relative intensity noise to that of the WT in nc12–nc14, and the downstream Even-skipped (Eve) and cephalic furrow (CF) show the same positional errors as these factors in WT. Our results indicate that threshold-dependent activation and self-organized filtering are not mutually exclusive and could both be implemented in early Drosophila embryogenesis.

Seed dormancy in Campanulaceae: morphological and morphophysiological dormancy in six species of Hawaiian lobelioids

We determined the requirements for dormancy break/germination and kind of dormancy in seeds of the Hawaiian lobelioids Cyanea kunthiana, Delissea rhytidoperma, Lobelia grayana, L. hypoleuca, Trematolobelia grandifolia, and T. singularis. Fresh seeds were incubated in light/dark at 15/6, 20/10, and 25/15 °C, and germination monitored at two-week intervals for 14 weeks. For each species, the mean embryo length (E): seed (S) length ratio was determined for freshly matured seeds and for seeds at the time the seed coat split but before radicle emergence (germination). The embryo in seeds of all six species incubated at 25/15 °C grew inside the seed prior to germination (42%–148% increase in E:S ratio, depending on species). Seeds of L. grayana and L. hypoleuca have morphological dormancy (MD); they germinated to 82%–98% at the three temperature regimes in 4 weeks. Seeds of the other species have nondeep simple morphophysiological dormancy (MPD) and require >4 weeks for maximum germination to occur. Our results add to the growing body of knowledge about the kind (class) of seed dormancy in Campanulaceae, which suggests that seeds of members of this family have either MD or MPD and embryos grow at warm (≥15 °C) temperatures.

First report on the germination requirement of Pterygopleurum neurophyllum seeds

Pterygopleurum neurophyllum is a class II endangered species and Red list class CR species in Korea. In this study, we considered the effects of cold stratification on embryo development in P. neurophyllum seeds, and analysed the effect of temperature and light conditions, immersion time in 50% H2SO4 and GA3 concentration on subsequent germination. The embryo of P. neurophyllum seeds showed elongation after four weeks of cold stratification (4°C) and embryo length was significantly increased after eight weeks. Germinated seeds were observed after 12 weeks of cold stratification. The cold-stratified (12 weeks) seeds showed the highest germination (23.1%) at 20°C. After 30 minutes H2SO4 immersion, germination of cold-stratified seeds was 29.4%. The GA3 concentration study showed the highest germination for seeds treated with 0.5 g L-1 GA3 (37.2%). The maximum germination across all treatment combinations was 79.8% for seeds given 30 minutes of 50% H2SO4 treatment and 12 weeks of cold stratification and then treated for 24 hours in 0.5 g L-1 GA3.