Brassinazole Resistant 1 Activity Is Organ-Specific and Genotype-Dependent in Barley Seedlings

Brassinosteroids (BRs) control many plant developmental processes by regulating different groups of transcription factors, and consequently gene expressions. The most known is BZR1, the main member of the BES1 family. However, to date, it is poorly characterized in crop species. The main goal of the presented study was to identify HvBZR1 and determine its activity in 5-day-old barley (the stage is related to one leaf on the main shoot and a few seminal roots) using two cultivars with different sensitivities to BRs. Using the anti-OsBZR1 antibody, we identified the forms of HvBZR1 transcription factor with different molecular weights, which can be related to different phosphorylated forms of serine/threonine residues. Two phosphorylated forms in the shoots and one dephosphorylated form in the roots were determined. A minor amount of the dephosphorylated form of the HvBZR1 in the Haruna Nijo shoots was also found. The phosphorylated forms gave a higher band intensity for Golden Promise than Haruna Nijo. The bands were similar in their intensity, when two different phosphorylated forms were compared in Golden Promise, while a reduced intensity was detected for the phosphorylated form with a lower molecular weight for Haruna Nijo. Degradation of the phosphorylated forms in the shoots (complete degradation in Golden Promise and significant but not complete in Haruna Nijo) and the presence of the dephosphorylated form in the roots were proven for the etiolated barley. In the case of Haruna Nijo, a wider range of the regulators of the BR biosynthesis and signaling pathways induced the expected effects, 24-EBL (0.001 µM) and bikinin (10 and 50 µM) caused low amount of the phosphorylated forms, and at the same time, a tiny band of dephosphorylated form was detected. However, the expression of genes related to the BR biosynthesis and signaling pathways was not a determinant for the protein amount.

Germination and morphological responses of Triticum aestivum L. to different concentrations of fluoride

A laboratory experiment was conducted on germination papers to study the effect of fluoride (F) at 0 (T1), 50 (T2), 100 (T3), 200 (T4), 250 (T5) and 300 (T6) ppm on germination and morphological parameters in wheat (Triticum aestivum L.) variety, HUW-234 at 2, 4 and 6 days after initiation of germination process. Fluoride toxicity caused reduction in germination per cent, germination index, coefficient of velocity of germination and germination energy (%) while mean germination time increased with fluoride concentration. Root and shoot lengths and dry matters decreased with increased concentrations of fluoride. Ratio of root: shoot weight increased with increased concentration of fluoride. Elongation of seminal roots was adversely affected by increased fluoride level. Increased fluoride level in the germination medium decreased RGR of seedlings progressively. Present study revealed that enhanced fluoride concentration in germination medium caused reduction in germination and germination related parameters.

Optimization of a Pre-Sowing Treatment of Corn Seeds with Low-Frequency Pulse Electric Field to Improve the Germination and Development of Seedlings

Corn is one of the key forage crops in agriculture. However, corn production in Russia still remains behind of its demand, so the search and development of technologies allowing to improve its yield are very relevant. Pre-sowing treatment of seeds of corn and other crops with physical fields provides stimulation of the growth and development of plants, but its efficiency depends on some parameters including duration of such treatment. The laboratory evaluation of the effect of a pre-planting treatment of corn seeds with low-frequency pulse electric field for 1–9 h on their germination, average lengths of the coleoptile and radicle root, and the number of seminal roots made it possible to determine the optimum exposure time (4 h) providing a significant improvement of germination (+26.7% of the control) and increase in the coleoptile length (+21.2% of the control). The maximum negative effect was revealed for a 5-h exposure; it resulted in a significant reduction of the coleoptile and radicle root lengths (421.7 and 16.3% of the control, respectively), as well as the reduction of the average number of seminal roots (4.8% of the control).

Evaluation and GWAS of radicle gravitropic response in a core rice germplasm population

Aims Since gravitropism is one of the primary determinants of root development, facilitating root penetration into soil and subsequent absorption of water and nutrients, we studied this response in rice. Methods The gravitropism of 226 Chinese rice micro-core accessions and drought-resistant core accessions were assessed through the modified gravity-bending experiment and genome-wide association analysis (GWAS) was used to map the associated QTLs. Results The average value of gravitropic response speed of seminal roots was 41.05°/h, ranging from 16.77°/h to 62.83°/h. The gravity response speed of Indica (42.49°/h) was significantly (P < 0.002) higher than Japonica (39.71°/h) subspecies. The gravitational response speed of seminal roots was significantly positively correlated with the number of deep roots (r = 0.16), the growth speed of seminal roots (r = 0.21) and the drought resistance coefficient (r = 0.14). Conclusions In total, 3 QTLs (quantitative traits) associated with gravitropic response speed were identified on chromosome 4, 11 and 12. There are some known QTLs relating to roots traits and drought resistance located nearby the QTLs identified here, which confirms the close relationship between radicle gravitropism and the drought resistance. From within these intervals, 5 candidate genes were screened and verified by qPCR in a few rice varieties with extreme phenotypic values, demonstrating that gene LOC_Os12g29350 may regulate gravitropism negatively. This may be a promising candidate to be confirmed in further studies.

Regulation of Sixth Seminal Root Formation by Jasmonate in Triticum aestivum L.

A well-developed root system is an important characteristic of crop plants, which largely determines their productivity, especially under conditions of water and nutrients deficiency. Being Poaceous, wheat has more than one seminal root. The number of grown seminal roots varies in different wheat accessions and is regulated by environmental factors. Currently, the molecular mechanisms determining the number of germinated seminal roots remain poorly understood. The analysis of the root system development in germinating seeds of genetically modified hexaploid wheat plants with altered activity of jasmonate biosynthesis pathway and seeds exogenously treated with methyl jasmonate revealed the role of jasmonates in the regulation of sixth seminal root development. This regulatory effect strongly depends on the jasmonate concentration and the duration of the exposure to this hormone. The maximum stimulatory effect of exogenously applied methyl jasmonate on the formation of the sixth seminal root was achieved at 200 μM concentration after 48 h of treatment. Further increase in concentration and exposure time does not increase the stimulating effect. While 95% of non-transgenic plants under non-stress conditions possess five or fewer seminal roots, the number of plants with developed sixth seminal root reaches up to 100% when selected transgenic lines are treated with methyl jasmonate.

Genome-wide association analysis unveils novel QTLs for seminal root system architecture traits in Ethiopian durum wheat

Background Genetic improvement of root system architecture is essential to improve water and nutrient use efficiency of crops or to boost their productivity under stress or non-optimal soil conditions. One hundred ninety-two Ethiopian durum wheat accessions comprising 167 historical landraces and 25 modern cultivars were assembled for GWAS analysis to identify QTLs for root system architecture (RSA) traits and genotyped with a high-density 90 K wheat SNP array by Illumina. Results Using a non-roll, paper-based root phenotyping platform, a total of 2880 seedlings and 14,947 seminal roots were measured at the three-leaf stage to collect data for total root length (TRL), total root number (TRN), root growth angle (RGA), average root length (ARL), bulk root dry weight (RDW), individual root dry weight (IRW), bulk shoot dry weight (SDW), presence of six seminal roots per seedling (RT6) and root shoot ratio (RSR). Analysis of variance revealed highly significant differences between accessions for all RSA traits. Four major (− log10P ≥ 4) and 34 nominal (− log10P ≥ 3) QTLs were identified and grouped in 16 RSA QTL clusters across chromosomes. A higher number of significant RSA QTL were identified on chromosome 4B particularly for root vigor traits (root length, number and/or weight). Conclusions After projecting the identified QTLs on to a high-density tetraploid consensus map along with previously reported RSA QTL in both durum and bread wheat, fourteen nominal QTLs were found to be novel and could potentially be used to tailor RSA in elite lines. The major RGA QTLs on chromosome 6AL detected in the current study and reported in previous studies is a good candidate for cloning the causative underlining sequence and identifying the beneficial haplotypes able to positively affect yield under water- or nutrient-limited conditions.

Benedict de Spinoza’s Virtue

Benedict de Spinoza (1632–1677) was about the most radical of the early modern philosophers who developed a unique metaphysics that inspired an intriguing moral philosophy, fusing insights from ancient Stoicism, Cartesian metaphysics, Hobbes and medieval Jewish rationalism. While helping to ground the Enlightenment, Spinoza’s thoughts, against the intellectual mood of the time, divorced transcendence from divinity, equating God with nature. His extremely naturalistic views of reality constructed an ethical structure that links the control of human passion to virtue and happiness. By denying objective significance to things aside from human desires and beliefs, he is considered an anti-realist; and by endorsing a vision of reality according to which everyone ought to seek their own advantage, he is branded ethical egoist. This essay identified the varying influences of Spinoza’s moral anti-realism and ethical egoism on post-modernist thinkers who decried the “naïve faith” in objective and absolute truth, but rather propagated perspective relativity of reality. It recognized that modern valorization of ethical relativism, which in certain respects, detracts from the core values of the Enlightenment, has its seminal roots in his works.

Genotypic variability of root and shoot traits of bread wheat (Triticum aestivum L.) at seedling stage

The evaluation of the embryonic root and stem of bread wheat (Triticum aestivum L.) in the early stage of development (seedling stage) can be a powerful tool in wheat breeding aimed at obtaining progenies with a greater early vigour. It is revealed that genotypes with faster early vigour have produced higher biomass and grain yield. In this study, the evaluation of traits of the embryonic root and the embryonic stem of 101 bread wheat genotypes was preformed at the 10-day old seedlings. The following eight morphological traits of roots and stems were analysed: primary root length, branching interval, the number of roots, total length of lateral roots, angle of seminal roots, stem length, root dry weight and the stem dry weight. Analysed lateral roots included seminal roots. The greatest, i.e. the smallest variability of observed traits was detected in the branching interval, i.e. the stem length, respectively. The highest positive correlation was determined between the primary root length and the total length of lateral roots. The cluster analysis, based on observed traits, shows that genotypes were clearly divided into two main clusters, A and B. The two clusters essentially differed from each other in the values of the following traits: primary root length, total length of lateral roots, root dry weight, stem dry weight and the stem length. Genotypes with shorter primary and lateral roots, lower root and stem dry weight and a shorter stem were grouped in the cluster B. On the other hand, the cluster A encompassed genotypes with values of these traits above or around the average. The values of the remaining analysed traits: the angle of seminal roots, the number of lateral roots and the branching interval varied greatly between obtained clusters. The cluster analysis showed the homogeneity of genotypes originating from Serbia and the region; their values of the root and stem length and weight were mostly around and below the average. However, the values of the angle of seminal roots, number of lateral roots and the branching interval were above average.

INFLUENCE OF SEED SIZE ON MAIZE SEEDLINGS WHEN SOWN UNDER WATER DEFICIT CONDITIONS

Seed size may affect the initial development of seedlings, especially under adverse conditions such as water deficit. The objective of this study was to characterize the influence of seed size on traits presented by maize seedlings under contrasting conditions of water availability. The experiment was conducted with a tolerant line (L91), a non-tolerant line (L57), and with the F2 resulting from the cross between those lines. The seeds were classified with the use of round-hole sieves and those retained on sieves of sizes 22, 20 and 18/64” were used. The seeds were sown in trays containing sand and, in order to simulate water deficit, the water retention capacity was adjusted to 10% (stress) and 70% (control). Four replications were used, with 25 seeds per treatment, which were stored in a growth chamber at 25 ºC for 7 days. Then the number of seminal roots, length of root and shoot, and their weights (fresh, dry and total) were evaluated. The seed size directly influences the development of maize seedlings, when subjected to water restriction, regardless of whether they are lines or F2. In this case, the larger-size sieves (22 and 20) were superior when compared with the size 18. In the early stages, the L57 was more tolerant to water restriction when compared with L91.

Increased seed carbohydrate reserves associated with domestication influence the optimal seminal root number of Zea mays

Background and AimsDomesticated maize (Zea mays ssp. mays) generally forms between two and six seminal roots, while its wild ancestor, Mexican annual teosinte (Zea mays ssp. parviglumis), typically lacks seminal roots. Maize also produces larger seeds than teosinte, and it generally has higher growth rates as a seedling. Maize was originally domesticated in the tropical soils of southern Mexico, but it was later brought to the Mexican highlands before spreading to other parts of the continent, where it experienced different soil resource constraints. The aims of this study were to understand the impact of increased seminal root number on seedling nitrogen acquisition and to model how differences in maize and teosinte phenotypes might have contributed to increased seminal root number in domesticated maize.MethodsSeedling root architectural models of a teosinte accession and a maize landrace were constructed by parameterizing the functional-structural plant model OpenSimRoot using plants grown in mesocosms. Seedling growth was simulated in a low-phosphorus environment, multiple low-nitrogen environments, and at variable planting densities. Models were also constructed to combine individual components of the maize and teosinte phenotypes.Key ResultsSeminal roots contributed about 35% of the nitrogen and phosphorus acquired by maize landrace seedlings in the first 25 days after planting. Increased seminal root number improved plant N acquisition under low-N environments with varying precipitation patterns, fertilization rates, soil textures, and planting densities. Models suggested that the optimal number of seminal roots for nutrient acquisition in teosinte is constrained by its limited seed carbohydrate reserves.ConclusionsSeminal roots can improve the acquisition of both nitrogen and phosphorus in maize seedlings, and the increase in seed size associated with maize domestication may have facilitated increased seminal root number.