Normal Seedling Development Research Articles

Physiological quality of green corn seeds under water stress conditions

This study aimed to evaluate the physiological quality of green corn seeds subjected to water stress. The experimental design used was completely randomized, in a 2 x 5 factorial arrangement, consisting of two corn hybrids (AG1051 and BRS3046) and five osmotic potentials (0; -0.4; -0.8; -1.2 and – 1.6 MPa) simulated with aqueous solutions of polyethylene glycol 6000 (PEG 6000), with four replications of 50 seeds per treatment, totaling 40 experimental units. The analyzed variables were: water content, germination, root protrusion, final root protrusion, germination speed index, root length and coleoptile length. There was a significant effect of the interaction between hybrid factors and osmotic potentials for all analyzed variables, except for final root protrusion, which showed an isolated effect for the two factors studied. The results obtained indicated a higher percentage of germination and initial development of green corn seedlings for green corn seeds, hybrids AG1051 and BRS3046 at the osmotic potential of 0.0 MPa. The germination and vigor of green corn seeds decrease under water stress conditions from the osmotic potential of -0.4 MPa induced by PEG 6000, inhibiting the development of normal seedlings, affecting seed viability. Hybrid AG1051 presents superior germination and vigor compared to BRS3046.

Pollen morphology and reproductive biology of Calophyllum brasiliense Cambess. (Calophyllaceae)

Pollen morphology and the reproductive biology of Calophyllum brasiliense were investigated in Parque Estadual das Fontes do Ipiranga, São Paulo, Brazil. The study encompassed pollen analyses using light, scanning, and transmission electron microscopy. Additionally, we collected data on reproductive biology, main visitors/pollinators, fruit set, and seed germination. The species exhibits individuals with perfect flowers (hermaphrodites) as well as male individuals with staminate and perfect flowers. Flowering occurs in October and November, and flowers have diurnal anthesis and pollen as a floral resource. Pollen grains are monads of medium size, isopolar, oblate-spheroidal to prolate-spheroidal, 3-(4)-zonocolporate, with exine fossulate-perforate with supratectal microechini. Hermaphrodite individuals have the highest proportion of malformed pollen due to their reduced grain size. The pollen grains from the hermaphrodite individuals displayed a low viability (0.06%), while those from male individuals had higher viability (66.38% and 55.78% for perfect and staminate flowers, respectively). The stigma was receptive throughout the anthesis period. Cross-pollination between perfect flowers of male and hermaphrodite individuals resulted in 8.80% success in fruit set, but led to the development of one abnormal seedling. Cross-pollination between staminate flowers and perfect flowers of hermaphrodite individuals showed a 7.70% success rate and the control group showed an 8.00% success rate, both groups leading to the development of normal seedlings. This tree species shows relatively low reproductive success and relies on pollinators (mainly Apis mellifera, Paratrigona subnuda, Tetragonisca angustula, and Halictidae sp. 1) for the setting of fruits and seeds.

Low nitrogen priming improves nitrogen uptake and assimilation adaptation to nitrogen deficit stress in wheat seedling.

Early-stage low nitrogen priming promotes root growth and delays leaf senescence through gene expression, enhancing nitrogen absorption and assimilation in wheat seedlings, thereby alleviating growth inhibition under nitrogen deficit stress and supporting normal seedling development. Verifying the strategies to reduce the amount of nitrogen (N) fertilizer while maintaining high crop yields is important for improving crop N use efficiency (NUE) and protecting the environment. To determine whether low N (LN) priming (LNP) can alleviate the impact of N-deficit stress on the growth of wheat seedlings and improve their tolerance to N-deficit stress, we conducted hydroponic experiments using two wheat cultivars, Yangmai 158 (YM158, LN tolerant) and Zaoyangmai (ZYM, LN sensitive) to study the effects of LNP on wheat seedlings under N-deficit stress. N-deficit stress decreased the plant dry weight, leaf area, and leaf N content (LNC), while LNP could significantly reduce this reduction. Distinct sensitivities to N-deficit stress were observed between the wheat cultivars, with ZYM showing an early decrease in leaf N content compared to YM158, which exhibited a late-stage reduction. LNP promoted root growth, expanded N uptake area, and upregulated the expression of TaNRT1.1, TaNRT2.1, and TaNRT2.2 in wheat seedlings, suggesting that LNP can enhance root N uptake capacity to increase N accumulation in plants. In addition, LNP improved the activity of glutamine synthase (GS) to enhance the capacity of N assimilation of plants. The relative expression of TaGS1 in the lower leaves of priming and stress (PS) was lower than that of no priming and stress (NS) after LNP, indicating that the rate of N transfer from the lower leaves to the upper leaves became slower after LNP, which alleviated the senescence of the lower leaves. The relative expression of TaGS2 was significantly increased, which might be related to the enhanced photorespiratory ammonia assimilation capacity after LNP, which reduced the N loss and maintained higher LNC. Therefore, LNP in the early stage can improve the N absorption and assimilation ability and maintain the normal N supply to alleviate the inhibition of N-deficit stress in wheat seedlings.

Thermal optima for seed germination of 30 tree species from Central Amazonia: a comparison of approaches and a new proposal

This study compared the seed germination of 30 tree species from Central Amazonia using a wide temperature range (5-40°C with 12 hours of light daily). Seeds were submitted to pre-germination treatments, whenever necessary, sown on vermiculite or germitest paper, and normal seedling development was assessed until stabilisation. With the same data set, seeds' optimal germination temperature (Topt ) was determined by comparing the following approaches: (i) 2-step, the temperature with the highest germination and the shortest time to seed population reach 50% of germination was chosen; (ii) the highest Germination Speed Index (GSI); (iii) using the formula developed by Olff and collaborators (Olff's approach); (iv) three species were evaluated with Covell's approach; and (v) new formulas for Topt calculation are proposed, based on germination success and five different variables of germination rate (Cipriani's approach). Comparing the results, Topt differed between 0.6-10.0°C. GSI and 2-step indicated generally higher values than Olff's formula. The minimum and maximum Topt differences between Cipriani's approaches were between 0.1-2.2°C. Our study showed that Toptshould be determined for each species as, even the 30 Amazonian tree species of the same habitat, Topt ranged between 22.5 and 32.5°C.

Exploiting the microbiome associated with normal and abnormal sprouting rice (Oryza sativa L.) seed phenotypes through a metabarcoding approach

Rice germination and seedlings’ growth are crucial stages that influence crop establishment and productivity. These performances depend on several factors, including the abundance and diversity of seed microbial endophytes. Two popular rainfed rice varieties cultivated in Cameroon, NERICA 3 and NERICA 8, were used for investigating the seed-associated microbiome using the Illumina-based 16 S rRNA gene. Significant differences were observed in terms of richness index between normal and abnormal seedlings developed from sprouting seeds, although no significant species evenness index was assessed within either phenotype. Two hundred ninety-two bacterial amplicon sequence variants were identified in seed microbiome of the rice varieties, and principal coordinate analysis revealed that microbial communities formed two distinct clusters in normal and abnormal seedling phenotypes. Overall, 38 bacteria genera were identified, belonging to 6 main phyla. Furthermore, the core microbiome was defined, and the differential abundance of 28 bacteria genera was assessed. Based on the collected results, putative bacterial genera were directly correlated with the development of normal seedlings. For most genera that are recognised to include beneficial species, such as Brevundimonas, Sphingomonas, Exiguobacterium, Luteibacter, Microbacterium and Streptomyces, a significant increase of their relative abundance was found in normal seedlings. Additionally, in abnormal seedlings, we also observed an increased abundance of the genera Kosakonia and Paenibacillus, which might have controversial aspects (beneficial or pathogenic), together with the presence of some genera (Clostridium sensu stricto) that are commonly correlated to sick plants. The putative functional gene annotation revealed the higher abundance of genes related to the metabolic biosynthesis of soluble carbohydrates and starch, tryptophan, nucleotides and ABC transporters in normal seedlings. Data presented in this study may help in further understanding the importance of the seed endophyte microbiome for driving a correct development of rice plants at the early stages and to identify possible beneficial bacteria for technological applications aimed to increase seed quality and crop productivity.

Arogenate dehydratases: unique roles in light-directed development during the seed-to-seedling transition in Arabidopsis thaliana.

The seed-to-seedling transition is impacted by changes in nutrient availability and light profiles, but is still poorly understood. Phenylalanine affects early seedling development; thus, the roles of arogenate dehydratases (ADTs), which catalyze phenylalanine formation, were studied in germination and during the seed-to-seedling transition by exploring the impact of light conditions and specific hormone responses in adt mutants of Arabidopsis thaliana. ADT gene expression was assessed in distinct tissues and for light-quality dependence in seedlings for each of the six-member ADT gene family. Mutant adt seedlings were evaluated relative to wild type for germination, photomorphogenesis (blue, red, far red, white light, and dark conditions), anthocyanin accumulation, and plastid development-related phenotypes. ADT proteins are expressed in a light- and tissue-specific manner in transgenic seedlings. Among the analyzed adt mutants, adt3, adt5, and adt6 exhibit significant defects in germination, hypocotyl elongation, and root development responses during the seed-to-seedling transition. Interestingly, adt5 exhibits a light-dependent disruption in plastid development, similar to a phyA mutant. These data indicate interactions between photoreceptors, hormones, and regulation of phenylalanine pools in the process of seedling establishment. ADT5 and ADT6 may play important roles in coordinating hormone and light signals for normal early seedling development.

Seed Priming and Pericarp Removal Improve Germination in Low-Germinating Seed Lots of Industrial Hemp

Industrial hemp (Cannabis sativa L.) is experiencing a resurgence in North America as an agricultural commodity. Germplasm improvement for locally adapted and stable cannabinoid production is an industry priority. This study used seed priming and pericarp removal to recover seedlings in low-germinating seed lots that could prove important for plant breeding and germplasm conservation. Both seed priming and pericarp removal improved early seed germination, but pericarp removal was more effective in improving overall final germination percentages. On average, pericarp removal improved final germination in low-germinating seed lots by approximately 38% compared to intact seed germination. In seeds with the pericarp removed, the initial germination substrate had an impact on normal seedling development following transplanting: those germinated for 2 to 3 days on rolled towels produced more normal seedlings compared to those started in Petri dishes. There was a dramatic increase in abnormal seedlings produced in the low-germinating seed lot initially germinated in a Petri dish wetted with 6 mL water where nearly 80% never transitioned to normal actively growing seedlings.

Seed Quality and Seedling Vigor in Peanut affected by Tomato Spotted Wilt Virus

Germination and vigor are physiological components of seed quality that contribute to a successful plant emergence under a wide range of environmental conditions. Many biotic and abiotic factors can affect seed quality. Tomato spotted wilt virus (TSWV) causes one of the most relevant problems in peanut (Arachis hypogaea L.), the tomato spotted wilt disease (TSW). Although TSW is not transmitted by seed, the presence of symptoms on the seed coat may impact seed quality and there is a lack of information on the effect of this disease on peanut seed quality. Therefore, the objective of this study was to evaluate the effect of TSW symptoms on the seed coat on the physiological seed quality of peanut genotypes. Seeds from five peanut genotypes were separated into two symptomology groups, asymptomatic and symptomatic for TSW. Germination and vigor tests were performed on seeds and seedlings. Germination and normal seedling development were not affected by TSW. Radicle length and seedling weight were mainly impacted by genotype, with little effect from TSW. Vigor differences were likely more related to the given genotype innate susceptibility to TSW during seed formation than the actual presence of TSW symptoms on the seed coat. Overall, the presence of symptoms on the seed coat did not affect the seed physiological quality of peanut genotypes, except for the TSWV susceptible cultivar ‘SunOleic 97R’.

Radiographic Imaging as a Quality Index Proxy for Brachiaria brizantha Seeds.

Efficient methodologies for automated seed quality evaluations are important for the seed industry. Advanced seed technology research requires the use of adequate methods to ensure good seed performance under adverse environmental conditions; thus, providing producers with detailed, quick, and accurate information on structural seed integrity and ensuring vigorous production. To address this problem, this study aimed to determine Brachiaria brizantha (Marandu cv., Piatã cv. and Xaraés cv.) seed quality through radiographic imaging analyses associated with vigor tests and anatomical characterizations. Brachiaria seed cultivars displaying different physical and physiological attributes were selected and subjected to the 1000-seed weight test, water content determinations, X-ray analyses, germination tests, and anatomical characterizations. The X-ray analyses made it possible to establish a relationship between the X-ray images and other determined variables. Furthermore, the X-ray images can indicate evidence of internal and external damage that could later compromise germination. The Marandu and Piatã cultivars presented the highest germination percentages, germination speed indices, normal seedling development, and cellular structure preservation compared to the Xaraés cultivar. To summarize, X-ray analyses are efficient methods used for the selection of higher physical quality cultivars and can aid in the decision-making processes of companies and seed producers worldwide.

The photomorphogenic repressors BBX28 and BBX29 integrate light and brassinosteroid signaling to inhibit seedling development in Arabidopsis.

B-box containing proteins (BBXs) integrate light and various hormonal signals to regulate plant growth and development. Here, we demonstrate that the photomorphogenic repressors BBX28 and BBX29 positively regulate brassinosteroid (BR) signaling in Arabidopsis thaliana seedlings. Treatment with the BR brassinolide stabilized BBX28 and BBX29, which partially depended on BR INSENSITIVE1 (BRI1) and BIN2. bbx28 bbx29 seedlings exhibited larger cotyledon aperture than the wild-type when treated with brassinazole in the dark, which partially suppressed the closed cotyledons of brassinazole resistant 1-1D (bzr1-1D). Consistently, overexpressing BBX28 and BBX29 partially rescued the short hypocotyls of bri1-5 and bin2-1 in both the dark and light, while the loss-of-function of BBX28 and BBX29 partially suppressed the long hypocotyls of bzr1-1D in the light. BBX28 and BBX29 physically interacted with BR-ENHANCED EXPRESSION1 (BEE1), BEE2, and BEE3 and enhanced their binding to and activation of their target genes. Moreover, BBX28 and BBX29 as well as BEE1, BEE2, and BEE3 increased BZR1 accumulation to promote the BR signaling pathway. Therefore, both BBX28 and BBX29 interact with BEE1, BEE2, and BEE3 to orchestrate light and BR signaling by facilitating the transcriptional activity of BEE target genes. Our study provides insights into the pivotal roles of BBX28 and BBX29 as signal integrators in ensuring normal seedling development.

Physiological potential and health of peanut seed treated with ozone

Peanut seed can be infected by pathogen diseases that adversely affect the oil crop’s value chain. Ozone gas (O3) can be an alternative for the control of fungal diseases due to its high oxidizing potential. In this study, we investigated the effects of O3 exposure time on physiological and health characteristics of seed from three peanut cultivars. Seed from peanut cultivars Granoleico, IAC OL3, and IAC 503 were analyzed for their health (blotter test) and physiological potential (germination, first count, and seedling length) after exposure to O3 for 0, 1, 8, and 16 h. Peanut seed physiological quality and health differed among cultivars. Exposure of seed from peanut cultivars IAC OL3, IAC 503, and Granoleico to O3 at a rate of 600 mg h-1 did not affect the development of normal seedlings as measured by the first count and germination, but seedling length increased, decreased, or was not affected in cultivars Granoleico, IAC 503, and IAC OL3, respectively. Also, O3 did not eradicate fungal infections in peanut seed treated with O3 at a rate of 600 mg h-1 for up to 16 h, but the incidence of the fungus Rhizopus sp. in seed from cultivars IAC OL3, Granoleico, and IAC 503 increased, decreased or was not affected, respectively, after 8 h.

Alternative methodology for the germination test in chemically treated corn hybrid seeds

The objective of this work was to identify the most suitable conditions for the evaluation of the germination test in corn seeds through the use of different substrates. Two tests were carried out for the development of the work. In test 1, the hybrid Morgan 30A37 PWV was used in a factorial scheme of 5 substrates with 8 chemical treatments. The seeds were treated industrially with the following insecticides: Inside FS, Inside FS + Maestro FS, Maestro FS, Poncho, Inside FS + BioCoat Corn, Inside FS + Maestro FS + BioCoat Corn and Maestro FS + BioCoat Corn. For test 2, the hybrid used was the FS533 PWV in a factorial scheme of 5 substrates and 5 treatments, in which the seeds received the industrial treatment with the insecticides: Inside FS, Inside FS + Maestro FS, Maestro FS and Poncho. Both tests were submitted to two temperatures (20°C and 25°C) and five substrates (germitest® paper; germitest® paper + sand; germitest® paper + soil; germitest® paper + coal and brown paper). The most suitable substrates for installing the germination test in chemically treated corn seeds were brown pepper and germitest® + charcoal. And the temperature of 20°C is the one that allows the most uniform and rapid development of normal seedlings in the germination test in treated hybrid corn seeds.

Light affects the germination and normal seedling development of Neotropical savanna grasses

AbstractThe Cerrado is a Neotropical savanna where grasses are a major biomass component in the open vegetation physiognomies. Invasive grasses are widely used as pastures in the Cerrado, and their presence may displace native species. The persistence of native grasses relies also on reproduction via seeds, which is often dependent on seeds found buried in the soil seed bank. The literature about the effects of light availability on the germination of Neotropical savanna grasses is scarce, and germination may lead to abnormal seedlings that develop only the root or the shoot. Germination trials that overlook this fact may overestimate the potential for seedling recruitment. Therefore, we tested the effects of light availability on the germination of nine native and two invasive grasses, addressing the production of normal seedlings. Seeds were germinated in the complete absence or the presence of light (12 h photoperiod under white light) for 30 days. Germination was defined as the sum of normal and abnormal seedlings. Eight species were light-dependent, decreasing the production of normal seedlings in the dark. Two native and one invasive species were non-responsive to the dark treatment, showing no change in germination or production of normal seedlings. Our results suggest that seeds buried in the soil seed bank are likely to show reduced germination and develop abnormal seedlings, reinforcing a bottleneck for the recruitment of native grasses. For invasive species, however, the potential of seedling recruitment was minimally reduced by light, suggesting a competitive advantage for the recruitment of these species.

Rocket Science: The Effect of Spaceflight on Germination Physiology, Ageing, and Transcriptome of Eruca sativa Seeds.

In the ‘Rocket Science’ project, storage of Eruca sativa (salad rocket) seeds for six months on board the International Space Station resulted in delayed seedling establishment. Here we investigated the physiological and molecular mechanisms underpinning the spaceflight effects on dry seeds. We found that ‘Space’ seed germination vigor was reduced, and ageing sensitivity increased, but the spaceflight did not compromise seed viability and the development of normal seedlings. Comparative analysis of the transcriptomes (using RNAseq) in dry seeds and upon controlled artificial ageing treatment (CAAT) revealed differentially expressed genes (DEGs) associated with spaceflight and ageing. DEG categories enriched by spaceflight and CAAT included transcription and translation with reduced transcript abundances for 40S and 60S ribosomal subunit genes. Among the ‘spaceflight-up’ DEGs were heat shock proteins (HSPs), DNAJ-related chaperones, a heat shock factor (HSFA7a-like), and components of several DNA repair pathways (e.g., ATM, DNA ligase 1). The ‘response to radiation’ category was especially enriched in ‘spaceflight-up’ DEGs including HSPs, catalases, and the transcription factor HY5. The major finding from the physiological and transcriptome analysis is that spaceflight causes vigor loss and partial ageing during air-dry seed storage, for which space environmental factors and consequences for seed storage during spaceflights are discussed.

Vigor test of (strong) normal intact Amburana cearensis (Allemão) A.C. Smith seedlings

Abstract: The aim of this study was to adapt the vigor test methodology of (strong) normal intact seedlings of Amburana cearensis and evaluate efficiency in physiological classification of seed lots. The study was conducted in two stages: morphological characterization of seedlings and physiological analysis of seed lots. To do so, the following tests were carried out: (strong) normal seedlings, germination, emergence, first count, germination speed index, tetrazolium, length of strong normal seedlings, length and dry mass of seedlings. The experimental design was completely randomized. The Tukey and Kruskal-Wallis tests were used to compare the results, and the correlation between the variables was analyzed by Spearman and Pearson coefficients. The seedlings of A. cearensis are semi-hypogeal phanerocotylar, with development of normal seedlings on the ninth day after sowing. The vigor test of strong normal seedlings, length of strong normal seedlings, dry matter, and tetrazolium led to physiological classification into different vigor levels. The vigor test of (strong) normal seedlings, the length of strong normal seedlings, and tetrazolium (vigor) were effective for vigor classification of A. cearensis seeds.

Germination and Seedling Growth of Genotypes Crambe abyssinica Submitted to Water Deficit

Determining drought tolerance in plants is an increasingly important feature due to the reduction of water resources, since water stress is one of the main environmental factors that limit agricultural growth and productivity. The objective of this study was to evaluate the tolerance of crambe (Crambe abyssinica Hochst) genotypes submitted to water stress induced by polyethylene glycol during germination and early growth of seedlings. A randomized block experimental design was used in a factorial scheme consisting of five crambe genotypes (FMS Brilhante, FMS CR 1203, 1307, 1312 and 1326) and five levels of osmotic potential [0.0 (control), -0.2, -0.4, -0.5 and -0.6 MPa] in five replicates of 40 seeds. Germination rate (%), normal seedling development (%), germination speed index, root and shoot length, total fresh matter, and water content of seedlings (%) were analyzed. Physiological quality of seeds and initial development of crambe genotypes was improved in the group submitted to Ψw = -0.2 MPa. Germination and vigor index of crambe seeds were hampered by reduction of the potential to -0.4 MPa. The genotype FMS CR 1203 was the most tolerant to water stress, whereas FMS CR 1307 and 1312 were the most sensitive, as corroborated by PCA.

Germination of Eugenia brasiliensis, E. involucrata, E. pyriformis, and E. uniflora (Myrtaceae) under water-deficit conditions

Abstract: This work aims at evaluating the tolerance of seeds of Eugenia brasiliensis Lam., E. involucrata DC., E. pyriformis Camb., and E. uniflora L. (Myrtaceae) to water deficit. Germination was carried out in polyethylene glycol 6000 solutions, at different osmotic potentials (0.0, -0.5, -1.0, -1.5, -2.0, -3.0, -4.0, and -5.0 MPa). The seeds were also placed in trays containing sand as substrate, and the water was replenished at different times, for up to 34 days. Seeds were evaluated as for their ability to undergoing a deficit period, and of germinating when water was made available again. In general, Eugenia spp. seeds were able to germinate at up to -1.5 MPa. In water potentials lower than 0.0 MPa, the beginning of germination experienced a delay, and it became better distributed throughout time. In the trays, the water restriction for up to 16 days did not limit normal seedling development. Seeds of Eugenia spp. were considerably tolerant to water deficit, as for both intensity and duration, which guarantees the development of seedlings and the propagation of the species.

Impact of fast and slow desiccation on Garcinia imberti seed and seedling vigour

Garcinia imberti Bourd. endemic to the southern Western Ghats is classified as endangered by the IUCN (2018). The seeds as the sole means of propagation with initial moisture content (MC) of 62.8% are sensitive to desiccation. Studies on the responses of the seed to drying require ascertaining of the critical moisture content (CMC) as a basic requisite for germplasm conservation. Responses of G. imberti seeds to fast drying with activated silica gel (25 ± 2 °C, 6 ± 1% RH) and to slow drying under laboratory conditions (28 ± 2°C, 60 ± 2% RH) were evaluated for seed and seedling vigour. When the MC was reduced to 56% by 48 hours of slow drying or 6 hours of fast drying, 75 to 90% normal seedlings were produced respectively. In the case of fast dried seed (6 hours), seed associated parameters except mean germination time showed peak values with maximum germination and enhanced root length. Below the CMCs of 16.4 and 26.3% (fast and slow drying respectively), half of the tested seeds become non viable. Thus for germplasm conservation the present study proposes 6 hour’s of fast drying to retain viability and normal seedling development of G. imberti.

Germination and vigor of linseed seeds under different conditions of light, temperature and water stress

Linseed (Linum usitatissimum L.), cultivated from seeds, is one of the oldest plants domesticated by humans and is popularly used as a medicine. It can be used as the raw material to produce oil and bran because it has high lipids content, fiber and proteins. Based on the economic potential of this species and the need for more information about its physiology, the goal of this study was to analyze the effects of light, temperature and water stress on the germination and vigor of linseed seeds. In experiment I the seeds were sown on paper at constant temperatures of 15, 20, 25 and 30 ºC in the presence and absence of light. In experiment II, the seeds were placed on paper germitest soaked in solutions of polyethylene glycol (PEG 6000) at osmotic potentials corresponding to zero, -0.10, -0.20, -0.30, -0.40, -0.50 and -0.60 MPa. To evaluate the physiological potential, the following tests were made: germination, first germination count, length and dry mass of seedlings, and water stress. It was found that the highest percentages of germination and vigor occurred at a constant temperature of 20 °C, both in the presence and absence of light. The reduction of the osmotic potential of the substrate promoted a significant decrease in the germination and vigor of the linseed seeds. Osmotic potentials equal or less than -0.30 MPa were harmful to germination and there was no normal seedling development starting at -0.50 MPa.

Label-free in situ imaging of oil body dynamics and chemistry in germination.

Plant oleosomes are uniquely emulsified lipid reservoirs that serve as the primary energy source during seed germination. These oil bodies undergo significant changes regarding their size, composition and structure during normal seedling development; however, a detailed characterization of these oil body dynamics, which critically affect oil body extractability and nutritional value, has remained challenging because of a limited ability to monitor oil body location and composition during germination in situ. Here, we demonstrate via in situ, label-free imaging that oil bodies are highly dynamic intracellular organelles that are morphologically and biochemically remodelled extensively during germination. Label-free, coherent Raman microscopy (CRM) combined with bulk biochemical measurements revealed the temporal and spatial regulation of oil bodies in native soya bean cotyledons during the first eight days of germination. Oil bodies undergo a cycle of growth and shrinkage that is paralleled by lipid and protein compositional changes. Specifically, the total protein concentration associated with oil bodies increases in the first phase of germination and subsequently decreases. Lipids contained within the oil bodies change in saturation and chain length during germination. Our results show that CRM is a well-suited platform to monitor in situ lipid dynamics and local chemistry and that oil bodies are actively remodelled during germination. This underscores the dynamic role of lipid reservoirs in plant development.