The aim of this study was to evaluate the tensile strength of the rachilla in spikelets of Polish cultivars of Festulolium braunii (K. Rich.) A. Camus during seed development and maturation. The investigations were carried out in 2009 - 2010 at the Plant Breeding, Szelejewo, Poland. The inflorescences were randomly harvested in June - July from plant collection in maintenance breeding of three Polish cultivars (Agula, Felopa, and Sulino). Using a specifically developed testing machine, tensile strength of the rachilla of individual spikelets were determined. Regardless of the F. braunii cultivar, the tensile strength of the rachilla decreased through consecutive growth stages. The highest tensile strength of the rachilla was observed during the phase of kernel watery ripe stage (BBCH 71) - it ranged from 510.1 mN in 'Agula' to 592.0 mN in 'Felopa'. At the fully ripe phase (BBCH 89), the value of this trait ranged from 19.2 mN in 'Agula' to 45.0 mN in 'Felopa'. It was also observed that in all tested cultivars of F. braunii, the spikelets located in the lower part of the spike were characterised by the highest tensile strength of the rachilla, whereas those in the upper part were characterised by the lowest values of this trait. This means that the caryopses in the spikelets located at the lower part of the inflorescence were less susceptible to shedding. Seed shedding the Polish F. braunii cultivars, especially 'Agula' and 'Sulino', may start as early dough and soft dough phases. By contrast, seed shedding 'Felopa' is moved to the later phases of seed maturation.

Roles for nitric oxide (NO) and reactive oxygen species (ROS) during pollen-tube growth have been well established in angiosperms, but there remains lack of information regarding their potential signalling roles in pollen tubes in gymnosperms. Here, the pollen-tube elongation of Arizona cypress (Cupressus arizonica Greene) was investigated. Nitric oxide, ROS, and actin were detected using their respective fluorescent probes. Both NO and ROS were observed in the nuclei of generative cells and pollen-tube cells, and in the cytoplasm in the tip region. An intracellular NO content in the pollen cells was lowered using an NO scavenger or an NO-synthase inhibitor. Similarly, an endogenous ROS content in the pollen cells was lowered using an NAD(P)H oxidase inhibitor. These treatments reduced pollen germination and pollen-tube growth, and induced severe morphological abnormalities. Inhibition of NO and ROS accumulation also severely disrupted the actin cytoskeleton in the pollen tubes. These data indicate that NO and ROS had signalling roles in pollen germination and pollen-tube formation in cypress.

With the extensive utilization of graphene nanomaterials, they inevitably enter our environment. The potential phytotoxicity and environmental impact of graphene oxide (GO) have recently attracted much attention. We designed the experiment based on seed germination, seedling morphology, physio-biochemical properties, and antioxidant enzyme activities of five rice genotypes (9311, MH63, R527, K866, and Nipponbare) under six concentrations of GO (0, 5, 10, 50, 100, and 150 mg dm^-3). We studied the effects of different concentrations of GO on germination index (GI), shoot length (SL) and root length (RL), adventitious root number, shoot and root fresh masses, root/shoot ratio, chlorophyll (Chl) content, malondialdehyde content, and activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Graphene oxide treatments significantly enhanced seed germination and root growth and inhibited shoot growth of all genotypes. Furthermore, we found a significant genotype-dependent response to GO treatments. According to the relative increment trend of GI, SL, and RL, root/shoot ratio, antioxidant enzyme activities (CAT, POD, and SOD), and Chl content, 'R527' showed more tolerance to GO treatments than the other four genotypes. The 'MH63' and 'K866' were more sensitive than 'Nipponbare' and '9311'. It indicates that the GO-tolerant genotype might avoid free radicals damage from GO by increased antioxidant enzyme activities. Moreover, we should consider the genotype differences when evaluating the potential phytotoxicity of GO and environmental risk to ecosystems.

The importance of Na⁺/H⁺ antiporters in salt tolerance in plants has been demonstrated in many studies, but much less is known about their protective role during drought stress. To study their possible contribution to water deficit tolerance, two closely related soybean Na⁺/H⁺ antiporters belonging to the intracellular NHX exchanger protein family, GmNHX3 and GmNHX1, were evaluated in transgenic Arabidopsis thaliana. A. thaliana plants ectopically expressing GmNHX3 or GmNHX1 displayed a more drought-tolerant phenotype compared to wild-type plants, which was accompanied by an increase in relative water content and chlorophyll content during stress conditions. Both GmHNX1 and GmHNX3 transgenic lines accumulated higher amounts of Na⁺ and K⁺ cations, showed increased antioxidant enzyme activities and less membrane damage due to lipid peroxidation under water deficit, as compared to non-transformed plants. Furthermore, plants expressing GmNHX3 showed an increased sensitivity to abscisic acid as deduced from stomatal closure and seed germination inhibition studies. Finally, a significant up-regulation of abiotic stress-related genes was observed in both transgenic lines compared to wild-type plants in response to abscisic acid and mannitol treatments. These results demonstrate that GmNHX3 and GmNHX1 antiporters confer protection during drought stress in A. thaliana and hence are potential genetic targets to improve drought tolerance in soybean and other crops.

Radicle growth of germinated seed of the root parasite O. ramosa is shown to be rapidly accompanied by secretion of proteins including pectinolytic enzymes, polygalacturonase and rhamnogalacturonase. These secretions peaked between 4 to 8 d after induction of germination and remained constant for some further days in the case of polygalacturonases. After 6 d, germinated seeds secreted proteins which exhibit peroxidase activity. The latter may be correlated with expression of OrPOX1, a putative gene encoding for secreted peroxidase. The involvement of these enzymes in host root attack and haustorium formation by the parasite is discussed.

In order to introduce drought tolerance and improved cell wall digestibility from fescue in fodder ryegrasses, we developed two amphiploid Festulolium synthetics. One is a synthetic composed of three selected drought tolerant F1 hybrid genotypes from a cross between tetraploid Lolium multiflorum and hexaploid Festuca arundinacea, further on called LMFA. The other is a synthetic composed of five selected genotypes with soft leaves from a cross between tetraploid Lolium perenne and tetraploid Festuca pratensis, further on called LPFP. We produced seeds in polycrosses of two generations of both amphiploids, i.e., syn1 and syn2, and tested them in plot trials to determine the yield and fodder quality. The syn1 of both Festulolium populations had a higher annual dry matter yield than the reference Lolium cultivars and Festulolium cultivars composed of the same parental species. However, the syn2 of LMFA did not show an improved drought tolerance during a dry growing season compared to other Festulolium cultivars, and the seed yield of LMFA syn1 was low and dropped extremely in syn2. The number of chromosomes of LMFA also decreased gradually from F1 to syn2, and there was a clear shift in chromosome composition towards the Lolium genome. The LPFP synthetic performed better. Although the sugar content was significantly lower than the sugar content of the perennial ryegrass cultivars, organic matter digestibility (OMD) of LPFP was as high as OMD of the tetraploid perennial ryegrass cultivars. The cell wall digestibility (NDFD) of LPFP was significantly higher than the NDFD of both parental species and higher than the NDFD of all tested Festulolium cultivars. The seed yield of LPFP was the same in syn1 and syn2. The chromosome number remained on average the same and no clear shift of the chromosome composition to one of the composing genomes was observed. Overall, chromosome analysis revealed a high number of aneuploidy in syn1 and syn2 generations of both LMFA and LPFP and a lot of variation in number of Lolium, Festuca and recombinant chromosomes, and in the Lolium:Festuca genome ratio was observed among different genotypes of the same population. Therefore, selection for genotypes with a more stable genome composition will be a prerequisite for a sufficient seed yield and a broader exploitation of these new Festulolium synthetics.

Gibberellins (GAs) regulate diverse aspects of growth and development, but their role in root development and lateral root (LR) formation is poorly understood. In this study, GA₃ was applied to soybean [Glycine max (L.) Merr] by seed soaking. The results showed that root length and root surface area were significantly inhibited in early stages after GA₃ treatment. Microscopic examination showed that GA₃ treatment changed the cortex thickness, the pericycle diameter, and cell size in main root. Interestingly, exogenous GA₃ increased the quantity of lateral root primordia (LRP), but LR number decreased in this period. Moreover, the content of GAs, auxin and abscisic acid in root was altered. RNA-seq results revealed that application of GA₃ not only changed the expression of genes in GA biosynthesis pathway, including GA20ox and GA2ox, but also the GA regulation genes and signalling pathway genes. The changes in expression of gene concerning other hormones were also detected. In addition, GA₃ altered cell wall biogenesis and degradation genes which might be related to the changes of root morphology. In response to increased GA₃, 103 transcription factors were detected. Thus, exogenous GA₃ changed the content of hormones in roots and affected the root development by regulating the expression of respective genes.

Sarcobatus vermiculatus (Hook) Torrey is a leaf succulent, sodium-accumulating shrub usually found in saline substrates of the Great Basin desert, Utah, USA. Laboratory experiments were conducted to determine the effect of salinity (0, 200, 400, 600, 800 and 1000 mM NaCl) and temperature (day/night: 5/15, 10/20, 15/25, 20/30, and 25/35°C) on seed germination. S. vermiculatus showed 100% germination in non-saline controls, at all thermoperiods. Percentage and rate of germination decreased with increases in salinity and few seeds germinated at even 1000 mM NaCl. High salinity exposure caused the loss of viability at higher temperature regimes, while some recovery was recorded in low salinity treatments.

Morphological traits of seeds of Festulolium braunii (K. Richt.) A. Camus cultivars were studied in relation to weather conditions. The obtained results show that morphological traits of seeds varied among cultivars and years of cultivation. The values of seed characteristics were higher in year 2016 due to more favorable weather conditions for plant growth. It was found that the husked seeds of Festulolium cultivars were characterized by a similar length and width regardless of the year, whereas naked seeds significantly differed in these characteristics. Mean values (from the research years) of seed parameters, such as thousand seed mass, area, convex area, shape factor, rectangle, as well as naked seed width showed variations among cultivars. At the same time, it was found that the mass of 1 000 seeds of individual cultivars showed the smallest variability in both years of the study (2.56 - 4.86 %) indicating a high stability of this trait. Thousand seed mass was significantly correlated with husked seed length / husked seed width ratio and husked seed length, and weakly correlated with yield.

Plant hormones play important roles in seed dormancy and dormancy breaking. We measured the hormone content in rice (Oryza sativa L. cv. Nona Bokra) seeds at different stages and with or without imbibition treatment. We identified 1 265 differentially expressed genes (DEGs) between dormant and dormancy-broken seeds using RNA-seq analysis: 1 015 genes were significantly up-regulated, while 250 genes were significantly down-regulated. Sixteen DEGs were selected as related to seed dormancy, and their expressions were validated using quantitative PCR. Three DEGs were in the same position as two reported dormancy QTLs, suggesting that they may be candidate genes that control the dormancy of rice seeds. Our study provides an important basis for cloning genes in dormant rice seeds and provides theoretical support for the study of the dormancy mechanism.

In vitro propagation protocol for Haemaria discolor (Ker) Lindl. var. dawsoniana by artificial cross-pollination and asymbiotic germination of seeds has been developed. Fruit set (100 %) was obtained when the pollinia and ovules of various aged flowers were used for pollination. In vitro germination of seeds obtained from capsules of various ages was achieved on half-strength Murashige and Skoog's (MS) medium supplemented with 3 % sucrose and 0.85 % agar. The germinated seedlings were cultured on half-strength MS medium with 0.2 % activated charcoal, 8 % banana homogenate, 0.1 mg dm^-3 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea (TDZ) and 1 mg dm^-3 α-naphthaleneacetic acid (NAA). Ninety-six percent of plantlets survived after hardening in greenhouse.

In plant breeding, polyploidization is an established technique to obtain superior phenotypic characteristics. In seed propagated agricultural crops, seed treatments with antimitotic agents are often used to obtain chromosome doubling. Here, we developed a method to induce polyploidization in clonally propagated fodder grasses Lolium, Festuca, and the intergeneric hybrid Festulolium. The aim was to obtain specific genotypes at both the diploid and tetraploid levels. We evaluated different types of plant explants, and the effects of the type, concentration, and application mode of three antimitotic agents (oryzalin, colchicine, and trifluralin) on the survival rate and the polyploidization efficiency. The treatment of greenhouse-grown tillers with antimitotics only resulted in mixoploids, while tissue culture propagated plants were successfully polyploidized. A shock pretreatment, using a high concentration of an antimitotic agent during a short period, successfully induced tetraploids in all three genera. Additionally, supplementing the tissue culture medium with a lower dosage of an antimitotic agent during minimal four weeks after the shock pretreatment further promoted polyploidization. By our methods, we were able to generate diploid and tetraploid plants with an identical genomic constitution but different ploidy allowing investigation of the effects of polyploidization on plant physiology and gene regulatory networks.

The effect of sucrose on fruiting, seed production, and seed germination of lesser centaury [Centaurium pulchellum (Sw.) Druce] was examined using explants of flowers and flower buds. Sucrose concentrations in the culture medium ranged from 0.003 to 0.3 M. It has been shown that the number of auxiliary buds, capsules dimension, number of viable seeds per capsule and seed dimensions increased with the increase of sucrose concentrations. The highest values were recorded at sucrose concentrations higher than 0.03 M, except for seeds size, which were larger at sucrose concentration ranging from 0.003 to 0.1 M. The germination of in vitro produced seeds was affected by previous culture history: a higher germination percentage was obtained in seeds that were raised from explants originally grown on medium with sucrose concentrations higher than 0.003 M.

To study the biological function of late embryogenesis abundant (LEA) proteins in Lepidium apetalum Willd., genes encoding LEA family proteins were identified from the seed transcriptome. The sequence most closely related to germination at a low temperature was selected and gene expressions in response to low temperature stress further studied. The results show that 27 LEA genes were expressed in seeds germinating at the low temperature: 3 genes were upregulated, 20 were downregulated, and 4 were not significantly different from controls. The most prominent of the upregulated genes, LaLEA1, contained an open reading frame of 624 bp and encoded 208 amino acids. The protein was rich in hydrophilic amino acids including threonine, alanine, glutamine, and lysine. It is predicted that the secondary structure contains α-helices and irregular curls. Real-time quantitative PCR results show that under low temperature stress, the expression of LaLEA1 was first downregulated and then upregulated rapidly, reaching its highest expression at 12 h, then the expression of LaLEA1 was reduced slightly but maintained higher than that of the non-stress group. As the expression of LaLEA1 was significantly altered in response to low temperature stress, we investigated the expression of LaLEA1 also in response to other abiotic stresses, i.e., salinity and drought. L. apetalum seedlings wilted in the early stage following NaCl or osmotic (polyethylene glycol) stresses, but recovered quickly, showing a strong tolerance. Real-time quantitative PCR results show that LaLEA1 was rapidly upregulated following salt and osmotic stresses, and its expression profile was closely related to NaCl or PEG concentrations. Expression was up to 7.9-fold higher than that of the control after 6 h of salt stress. These results suggest that L. apetalum seedlings responded quickly to salt stress. The response to osmotic stress was slightly slower; expression of LaLEA1 was 6.0-fold higher than that of the control after 12 h. Thus, LaLEA1 played an important role in abiotic stress tolerance. These results provide a basis for further analysis of the role of the LEA genes in the stress resistance of L. apetalum.

Contents of total free [PA(S)] and conjugated polyamines [PA(SH), PA(PH)] were higher in turnip (Brassica rapa L. cv. Rapa) seeds during imbibition (0-36 h) and radicle protrusion (36-48 h) than during the further growth (10 d). Ethylene production was activated with the protrusion, reaching a maximum at the second day of germination and dropping afterwards. The application of ethrel accelerated radicle emergence but the direct intervention of ethylene in the breaking of the seed coat was not clear from the use of ethylene-biosynthesis inhibitors (CoCl₂ and AVG). Finally, in this work the gene BrACO2 was characterized. Although its expression was not detected in seeds through zygotic embryogenesis, it increased concomitantly with the germination process.

To study the biological function of activity of bcl complex (ABC1) proteins in Lepidium apetalum Willd., genes encoding ABC1 family proteins were identified from the seed transcriptome. The sequence most closely related to germination at a low temperature was selected and gene expressions in response to low temperature stress further studied. The results show that 21 ABC1 genes were expressed in seeds germinating at the low temperature: 4 genes were upregulated, 6 were downregulated, and 11 were not significantly different from controls. The results of fluorescence quantification of the low-temperature stress on the seedlings of 7-d-old L. apetalum showed that seven genes were up-regulated, six genes were down-regulated, and eight genes had no significant difference. Real-time quantitative PCR results show that under the low temperature stress, the expression of the LaAbc1-3 gene increased, but its expression decreased after some time. The expression of this gene increased again after removing the low temperature stress. The expression of LaAbc1-21 gene in L. apetalum seedlings showed a trend of decreasing first and then increasing. The LaAbc1-3 gene was insensitive to salt stress. Expression of the LaAbc1-21 gene was significantly up-regulated during the salt stress. Under osmotic stress, the expression of the LaAbc1-3 gene was down-regulated, and the expression was negatively correlated with polyethylene glycol (PEG-6000) concentration. Under the PEG-6000 treatment, the expression of the LaAbc1-21 gene was significantly up-regulated, and the expression was positively correlated with concentration. These results provide a basis for further analysis of the role of the ABC1 genes in the stress resistance of L. apetalum.

Aims of the present two-year study were to evaluate the feasibility and identify potential drawbacks of the greenhouse/outdoors parallel plant growth methods for investigation of the effects of various winter chilling regimes on flowering quality indicators of four Greek olive cultivars, namely Mastoidis, Amfissis, and Lefkolia Serron (originating from mountainous and colder areas) compared to cv. Koroneiki (grown mainly in plain warm areas). Groups of potted olive plants were either grown outdoors under ambient temperature or transferred into a greenhouse for one, two, or three months during winter in Crete, Greece. During the first year, chilling accumulation deficit caused a marked decrease in the number of inflorescences per plant in all four olive cultivars. In the second year, chilling accumulation deficit had a negative effect on the number of inflorescences per plant in 'Mastoidis' at 3-month greenhouse treatment but not at all in 'Koroneiki'. Chilling deficit caused an overall decrease in the number of flowers per inflorescence in both 'Koroneiki' and 'Mastoidis' as well as in the percentage of morphologically perfect flowers. The width and length of inflorescences were not affected by chilling deficit in both the cultivars. In vitro pollen germination was reduced in all greenhouse treatments in 'Koroneiki'; however, this effect was significant only after 3 month, whereas no effect was observed in 'Mastoidis'. The results of the present study may contribute to understanding olive flowering biology and selecting appropriate cultivars for new plantations according to historical meteorological data and predicted climate change scenarios.

In vitro flowering protocols were developed for a limited number of early flowering pea (Pisum sativum L.) cultivars. This work was undertaken to understand the mechanisms regulating in vitro flowering and seed-set across a range of pea genotypes. Its final goal is to accelerate the generation cycle for faster breeding novel genotypes. We studied the effects of in vivo and in vitro applications of the antigibberellin Flurprimidol together with radiation of different spectral compositions on intact plants, plants with the meristem removed, or excised shoot tip explants. Based on our results, we present a simple and reliable system to reduce generation time in vitro across a range of pea genotypes, including mid and late flowering types. With this protocol, more than five generations per year can be obtained with mid to late flowering genotypes and over six generations per year for early to mid flowering genotypes.

Floral phenology, pollen quality and seed set of Plantago crassifolia plants, grown in the presence of increasing NaCl concentrations, were studied to test how this Mediterranean halophyte responded to salt stress during the reproductive phase of its life cycle. "Reproductive success" was maximal in plants grown in non-saline conditions, or in the presence of 100 mM NaCl, but it was negatively affected by higher salinities, due to a progressive reduction of pollen fertility, seed set, and seed viability.

Two ginseng species Panax vietnamensis and Panax stipuleanatus are precious medicinal plants restricted in several Vietnam provinces. They are very limited and endangered due to degraded habitats and over-harvesting. To preserve these two species, we used eight nuclear microsatellite markers to investigate genetic variability from the nine populations with 246 individuals for these two ginseng species. Our findings showed a moderate genetic heterozygosity in two species, P. vietnamensis (H_E = 0.386) and P. stipuleanatus (H_E = 0.342). Deficiency of heterozygosity was observed in all the studied populations of P. vietnamensis and three populations of P. stipuleanatus. Some populations had high allelic richness for both species. Private alleles were determined in all the studied populations of P. vietnamensis and two P. stipuleanatus populations. Genetic differentiation was low in two ginseng species. However, habitat loss, over-utilization and over-harvesting can be the main causes of reduced genetic heterozygosity. Neighbor-joining tree and discriminant analysis of principal components detected three major genetic groups. Finally, based on our findings, we propose in situ conservation of populations with high expected heterozygosity, allelic richness, and private alleles. Seed collection should be performed for ex-situ conservation as genetic pools in the future.

Seedling greening upon irradiance is essential for the survival of plant after germination. Here, we studied the role of nitric oxide (NO) in regulating the accumulation of chlorophyll during greening of Arabidopsis seedlings, and we also investigated the changes of ATP in the chloroplast and cytoplasm during greening by using a fluorescent protein sensor (Ateam 1.03-nD/nA) based on fluorescence resonance energy transfer (FRET) and the effects of NO on the changes of ATP content. The results showed that the content of NO, chlorophyll, and ATP in the chloroplast and cytoplasm increased with the increase of greening time. L-NAME, an inhibitor of NO, not only decreased the accumulation of chlorophyll content but also reduced the ATP content in the chloroplast and cytoplasm during the greening of Arabidopsis seedlings. Therefore, these experiments indicate that the accumulation of chlorophyll and changes of ATP during greening of etiolated Arabidopsis seedlings are mediated by nitric oxide.

The capacity of extracellular self-DNA (esDNA) to inhibit growth is getting more research attention as this could be explored for several purposes, including the development of specific bioherbicides. While the inhibitory effect has been studied in several dicotyledon species, little is known about the effects and subsequent signaling processes in monocots. Here, we measured the growth, counted the number of lateral and crown roots, determined greenness index, quantified the production of O₂^.- and H₂O₂, and determined the expressions of genes encoding antioxidant enzymes (SODs and CATs) in rice (Oryza sativa L.), a model plant of monocots. After 7 d of germination, rice roots were exposed to 0, 75, and 150 µg cm^-3 of esDNA. Inhibitory effect was found to be negatively correlated to esDNA concentration, as indicated by the length of primary roots. Interestingly, this negative effect was only observed in the directly exposed organ (root) but not in the length of shoot or fresh mass of the whole seedling. The percentage of greenness index of leaves and number of crown and lateral roots were also similar across treatments. However, esDNA exposure to root increased production of O₂^.- and H₂O₂ in the root. At the molecular level, the response was characterized by the decreased expression of the antioxidant genes SOD3, CATB, and CATC. These findings suggest that esDNA inhibits rice growth locally in, e.g. in treated roots, and the responses involve increased production of ROS and suppression of antioxidants. This study could be the basis for determining the combination of concentration and period of exposure that might significantly inhibit total growth of monocot weeds with a minimum effect on the crop.

Plants exhibit morphological plasticity in response to changes in the proportion of far-red radiation (FR). However, little is known about the response to a sudden increase of FR component. Cucumber seedlings were acclimatized to radiation without FR (FR-) for 1 - 5 d after germination, and then transferred to radiation containing FR (FR+) at levels similar to those in natural sunlight. Other seedlings were acclimatized to FR- or FR+, which was maintained continuously. The sudden increase in FR damaged the cotyledons and the first true leaf, especially when radiation was changed from FR- to FR+ at days 3 or 4 after germination. Necrosis of the damaged leaves may have resulted from inhibition of water flow in leaf xylem, because wilting and decreased stomatal conductance were observed simultaneously with leaf necrosis. Plants in the treatment groups that showed the most frequent damage showed two peaks in cotyledon elongation. This suggests that the leaves that had been acclimatized to FR- were easily damaged by the sudden promotion of leaf expansion caused by FR+.

The “Centre for Experimental Plant Biology”, a joint project of the Institute of Experimental Botany of the Czech Academy of Sciences and CEITEC (represented by Mendel and Masaryk Universities), focused on elucidating  the mechanisms of plant responses to abiotic and biotic stresses and their combinations at the cellular level, in intact plants during vegetative and reproductive stages, and fruit development. The consortium demonstrated the importance of shared research facilities, complementary approaches, and knowledge exchange, addressing demanding questions  in plant biology. The consortium made breakthrough in plant-pathogen interactions, including identification of  exocyst-syntaxin cooperation in non-host resistance. The results confirmed the fundamental role of phytohormones in stress responses, including negative correlation of leaf bioactive gibberellins with drought stress, and the role of cytokinins in ROS homeostasis, sulphur metabolism, and heat stress responses, including volatile emission. Molecular analyses revealed expansin-mediated cell wall remodelling, brassinosteroid-mediated regulation of root growth through PIN2, the role of ALBA and LARP6C proteins in pollen development under abiotic stress, and heat stress impact on fertilization rate, embryo and seed development. Gene Set Enrichment and RNA-Seq analyses allowed to identify crucial genes involved in the apple scab resistance network. The main results obtained during the five-year project are summarised here.

Using in vitro culture, we determined the effect of photoperiod during growth of Chenopodium rubrum mother plants on vegetative and reproductive development of offspring. Photoperiod during flowering induction of mother plants (the first 6 d after the germination) has the key influence on seed germination and offspring growth, while offspring flowering and seed maturation is determined by photoperiod their mothers experienced during, and shortly after, flowering induction. The mechanism can be through changes in seed protein pattern which we found dependent on photoperiod experienced by mother plants.

An efficient protocol for encapsulation of nodal segments of Vitex negundo L. has been developed for the production of non-embryogenic synthetic seeds. The encapsulations of nodal segments were significantly affected by the concentrations of sodium alginate and calcium chloride. A 3 % Na₂-alginate with 100 mM CaCl₂ has been found to be optimum concentration for the production of uniform synthetic seed. For germination, the synseeds were cultured on Murashige and Skoog (MS) basal medium supplemented with kinetin (KIN) and α-naphthalene acetic acid (NAA) either singly or in various combinations. MS medium containing 2.5 μM KIN in combination with 1.0 μM NAA was found to be the optimum for maximum (92.6 ± 3.71 %) plantlet conversion frequency. Well developed regenerated plantlets were hardened, acclimatized and established in field, where they grew well without any detectable variation.

The objective of this research was to investigate how ferulic and p-coumaric acids affect lipid and fatty acid composition during canola (Brassica napus L.) seed germination. Data showed that both compounds increased total lipid and fatty acid contents in the cotyledons during germination. The largest accumulation in lipids occurred at 1.0 mM p-coumaric acid with an increase in all unsaturated fatty acids. The results suggest that allelochemicals interfere in canola seed germination by reducing lipid mobilization.

Potato (Solanum tuberosum L.) cv. Eshu 10 was used to investigate the effects of exogenous gibberellic acid (GA₃), abscisic acid (ABA), and low-temperature stress on changes of hormone content, expression patterns of StTCP15 gene, and tuber dormancy characteristics. Under GA₃ treatment and low-temperature stress, tuber dormancy was broken in about one week sooner compared with the control group, but ABA treatment did not significantly promote the breaking of tuber dormancy. The results of hormone determination using liquid chromatography-mass spectrometry (LC-MS/MS) showed that the content of ABA in tubers treated with GA₃ or low-temperature stress was lower than in the control group, and it was higher than in the control group under ABA treatment. The GA₃ content of tubers was higher than in the control group under GA₃ treatment and lower under low-temperature stress. During dormancy, the ABA content continued to increase and GA₃ content fluctuated, ABA content rapidly decreased and GA₃ content rapidly increased when the dormancy was breaking, and both ABA content and GA₃ content increased during germination. The results from the assay of real-time quantitative PCR showed that the expression of the StTCP15 gene was continuously increased during the dormant period in all groups, and the expression of the StTCP15 gene was the highest at the time of dormancy release. The expression of the StTCP15 gene was increased about 15 times on the 7^th d under low-temperature stress and was restored at room temperature. Thus, the StTCP15 gene can respond to GA₃, ABA, and low-temperature stress and may be involved in the release of potato tuber dormancy.

6-Methoxy-2-benzoxazolinone (MBOA) inhibited germination of rice (Oryza sativa L.), wheat (Triticum aethiopicum Jakubz), rye (Secale cereale L.), onion (Allium cepa L.), wild oat (Avena fatua L.), barnyard grass [Echinochloa crus-galli (L.) Beauv.], ryegrass (Lolium rigidum Gaudin), cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), tomato (Lycopersicum esculentum Mill.), carrot (Daucus carota L.) and amaranth (Amaranthus retroflexus L) and the inhibition increased with increasing MBOA concentrations. MBOA also inhibited the induction of α-amylase in these plant seeds and the inhibition increased with increasing MBOA concentrations. There were variations in sensitivity of these plant species to MBOA, and species of family Poaceae (barnyard grass, wild oat, rice, rye, ryegrass, and wheat) were less sensitive to MBOA than the other plant species.

Trehalose, which plays important roles in resistance to abiotic stresses and preservation of biological activity in plants, is synthesized by two key enzymes, trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP). Therefore, the expressions of the TPS and TPP genes directly affect trehalose synthesis and stress resistance of plants. In this study, CkTPS and CkTPP from Caragana korshinskii were identified, and the role of trehalose synthesis in the adaptation of this desert plant to adverse conditions was investigated. Higher CkTPS and CkTPP expressions were observed in the roots, whereas expressions were much lower in leaves and stems, and their expressions were upregulated under drought stress. Histochemical analyses showed that β-glucuronidase expression driven by the CkTPS and CkTPP promoters was strongly induced by abiotic stresses and phytohormones, such as abscisic acid, gibberellin, methyl jasmonate, and mannitol, which suggests that trehalose synthesis may be regulated by various signaling pathways. To determine the functional mechanism underlying the role of trehalose synthesis in regulating drought response in plants, CkTPS and CkTPP were introduced into Arabidopsis. Compared to wild-type (WT) plants, these transgenic plants showed higher germination rate, survival, less damage, better shoot growth, and longer roots under drought stress. Moreover, transgenic plants had a significantly higher content of proline, chlorophyll, trehalose, and activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and lower malondialdehyde (MDA) content than WT controls. Double-transgenic plants carrying CkTPS and CkTPP showed better growth and stronger drought tolerance than either single transgenic plant line. These results provide a theoretical and experimental basis for further understanding the function and regulatory mechanism of CkTPS and CkTPP, as well as the possibility of their application for improving drought tolerance in crops through genetic engineering.