New insights into the role of cyanide in the promotion of seed germination in tomato

Background Cyanide is a natural metabolite that exists widely in plants, and it is speculated to be involved in the regulation of various growth and development processes of plants in addition to being regarded as toxic waste. Previous studies have shown that exogenous cyanide treatment helps to improve seed germination, but the mechanism is still unclear. In this study, tomato (Solanum lycopersicum cv. Alisa Craig) was used as the material, and the effects of cyanide pretreatment at different concentrations on tomato seed germination were investigated. Results The results showed that exogenous application of a lower concentration of cyanide (10 μmol/L KCN) for 12 h strongly increased the tomato seed germination rate. RNA-Seq showed that compared with the control, a total of 15,418 differentially expressed genes (P<0.05) were obtained after pretreatment with KCN for 12 h, and in the next 12 h, a total of 13,425 differentially expressed genes (P<0.05) were regulated. GO and KEGG analyses demonstrated that exogenous KCN pretreatment was involved in regulating the expression (mainly downregulation) of seed storage proteins, thereby accelerating the degradation of stored proteins for seed germination. In addition, KCN pretreatment was also involved in stimulating glycolysis, the TCA cycle and oxidative phosphorylation. Notably, it is shown that KCN acted on the regulation of plant hormone biosynthesis and perception, i.e., down-regulated the gene expression of ABA biosynthesis and signal transduction, but up-regulated the expression of genes related to GA biosynthesis and response. Consistent with this, plant hormone measurements confirmed that the levels of ABA were reduced, but GA levels were induced after pretreatment with KCN. Conclusion These findings provide new insights into the regulation of seed germination by cyanide, that is cyanide-mediated seed germination occurs in a time- and dose-dependent manner, and is related to the mobilization of energy metabolism and the regulation of some plant hormone signals.

Mobilization of seed storage proteins is crucial to high vigor in common bean seeds

ABSTRACT: Seed germination is a complex process controlled by many factors, in which physical and biochemical mechanisms are involved and the mobilization of reserves is crucial for this process to occur. Although, seed reserve mobilization is usually thought to be a post-germination process, seed reserve proteins mobilization occurs during germination. This study quantified seed proteins of bean genotypes during different hydration times, in order to understand the process of protein mobilization and whether there is relationship of this biochemical component with seed vigor. This study was conducted using seeds with different levels of vigor, genotypes with highest (13, 42, 55 and 81) and lowest (07, 23, 44, 50, IPR-88-Uirapurú and Iapar 81) physiological quality. High vigor genotypes showed greater efficiency in hydrolysis and mobilization of protein component, because they presented low globulins content in cotyledons at radicle protrusion in relation to low vigor genotypes (07, 23 and 50). The protein alpha-amylase inhibitor, observed in all genotypes, is involved with the longer time needed for radicle protrusion, according to the band intensity difference in genotypes 07, 44 and Iapar 81.

Functions and Composition Variations of Wheat Glutenin Proteins in Steamed Bread and Noodles

As a major food crop, wheat offers indispensable energy and nutrients to humans worldwide. With the living standards rising, the demand of high-quality wheat increases sharply. Wheat gluten proteins (glutenins and gliadins) are important components of seed storage proteins that affect the elasticity, strength or viscosity of dough. In this review, we summarize the composition of glutenin subunits in wheat grain and analyze the impact of glutenin on the traditional Chinese foods: steamed bread and noodles. Furthermore, we summarize the molecular markers used for wheat quality breeding. The advent of the recent wheat genomic will speed up the identification and quality breeding of novel glutenins.

Progressive Aggregation of 16 kDa Gamma-Zein during Seed Maturation in Transgenic Arabidopsis thaliana

Prolamins constitute a unique class of seed storage proteins, present only in grasses. In the lumen of the endoplasmic reticulum (ER), prolamins form large, insoluble heteropolymers termed protein bodies (PB). In transgenic Arabidopsis (Arabidopsis thaliana) leaves, the major maize (Zea mays) prolamin, 27 kDa γ-zein (27γz), assembles into insoluble disulfide-linked polymers, as in maize endosperm, forming homotypic PB. The 16 kDa γ-zein (16γz), evolved from 27γz, instead forms disulfide-bonded dispersed electron-dense threads that enlarge the ER lumen without assembling into PB. We have investigated whether the peculiar features of 16γz are also maintained during transgenic seed development. We show that 16γz progressively changes its electron microscopy appearance during transgenic Arabidopsis embryo maturation, from dispersed threads to PB-like, compact structures. In mature seeds, 16γz and 27γz PBs appear very similar. However, when mature embryos are treated with a reducing agent, 27γz is fully solubilized, as expected, whereas 16γz remains largely insoluble also in reducing conditions and drives insolubilization of the ER chaperone BiP. These results indicate that 16γz expressed in the absence of the other zein partners forms aggregates in a storage tissue, strongly supporting the view that 16γz behaves as the unassembled subunit of a large heteropolymer, the PB, and could have evolved successfully only following the emergence of the much more structurally self-sufficient 27γz.

Wheat Proteins: A Valuable Resources to Improve Nutritional Value of Bread

Triticum aestivum, commonly known as bread wheat, is one of the most cultivated crops globally. Due to its increasing demand, wheat is the source of many nutritious products including bread, pasta, and noodles containing different types of seed storage proteins. Wheat seed storage proteins largely control the type and quality of any wheat product. Among various unique wheat products, bread is the most consumed product around the world due to its fast availability as compared to other traditional food commodities. The production of highly nutritious and superior quality bread is always a matter of concern because of its increasing industrial demand. Therefore, new and more advanced technologies are currently being applied to improve and enrich the bread, having increased fortified nutrients, gluten-free, highly stable with enhanced shelf-life, and long-lasting. This review focused on bread proteins with improving wheat qualities and nutritional properties using modern technologies. We also describe the recent innovations in processing technologies to improve various quality traits of wheat bread. We also highlight some modern forms of bread that are utilized in different industries for various purposes and future directions.

Genetic diversity of the Algerian peanut population analyzed using morphological markers and seed storage proteins

Background. The peanut is one of the most important oil crops suitable for cultivation in the tropical areas of the world. Despite its agronomic importance, few studies have been carried out to assess the morphogenetic diversity of Arachis hypogaea L., especially in East African countries. The major interest of this morphologic study lies in the potential of this species to provide useful genes for the improvement of cultivated peanuts. To date, no study has been performed in Algeria to characterize local peanut varieties.Materials and methods. Thirty peanut accessions were collected from four principal areas of peanut production in Algeria. Genetic characterization using 15 agronomic characters and 25 morphological descriptors showed a high level of diversity among accessions. Principal Component Analysis and the Hierarchical Ascendant Classification were made to clarify the genetic relationship between peanut accessions.Results and discussion. Results showed that leaflet size (length and width), seed shape and size, oil content, and branching pattern were the principal characters to discriminate the screened A. hypogaea accessions. In addition to that, the weights of 10 pods and 100 seeds were the most variable traits and presented a CV of 42.53% and 40.12%, respectively. On the other hand, total storage proteins extracted were separated using SDS-PAGE and revealed thirty bands that were used to generate a matrix and make a cluster analysis using the UPGMA method, exhibiting different storage proteins compositions. Moreover , the phenotypic diversity observed agrees with the storage protein profile diversity, while the accessions grouped in similar clusters belong to the two subspecies of A. hypogaea. The results of the current study show that morphological traits and seed storage proteins can be useful for exploring the diversity among A. hypogaea accessions.

Protein reservoirs of seeds are composites of amyloid and amyloid-like structures

Seed storage proteins, well-known for their nutritional functions are sequestered in protein bodies. However, their biophysical properties at the molecular level remain elusive. Based on the structure and function of protein bodies found in other organisms, we hypothesize that the seed protein bodies might be present as amyloid structures. When visualized with a molecular rotor Thioflavin-T and a recently discovered Proteostat® probe with enhanced sensitivity, the seed sections showed amyloid-like signatures in the protein storage bodies of the aleurone cells of monocots and cotyledon cells of dicots. To make the study compliant for amyloid detection, gold-standard Congo red dye was used. Positive apple-green birefringence due to Congo red affinity in some of the areas of ThT and Proteostat® binding, suggests the presence of both amyloid-like and amyloid deposits in the protein storage bodies. Further, diminishing amyloid signature in germinating seeds implies the degradation of these amyloid structures and their utilization. This study will open new research avenues for a detailed molecular-level understanding of the formation and utilization of aggregated protein bodies as well as their evolutionary roles.

Transcriptomic, Metabolomic, and Physiological Analyses Reveal That the Culture Temperatures Modulate the Cryotolerance and Embryogenicity of Developing Somatic Embryos in Picea glauca

Cryopreservation is one of the key technologies for the mass propagation of conifers via somatic embryogenesis. Cryotolerance and embryogenecity of conifer somatic embryos (SEs) could be affected by different temperature treatments, for which the underlying mechanisms were unknown. In this study, the developing SEs of Picea glauca obtained their cryotolerance with a survival rate of 100% when cultured on maturation medium at either 23°C for 4 weeks or 4°C for 10 weeks. However, only the embryos that underwent 4°C acclimation remained high embryogenicity, i.e., 91.7% based on cryovials or 29.3% on the plant tissue. Analysis of differentially expressed genes (DEGs) revealed that both 23 and 4°C treatments led to drastic changes in the gene expression, i.e., 21,621 and 14,906 genes, respectively, and the general increase in many oligosaccharides and flavonoids, in addition to the content change of proline (1.9- and 2.3-fold at 23 or 4°C) and gallic acid (6,963- and 22,053-fold). There were 249 significantly different metabolites between the samples of 23 and 4°C treatments and the changing trend of the sorbitol, fatty acids, and monosaccharides differed between these samples. During 4°C-acclimation, the metabolites of the arginine biosynthesis pathway increased between 2.4- and 8.1-fold, and the expression of antioxidant genes was up-regulated significantly. At 4°C, the up-regulated genes were for germ-like proteins, instead of seed storage proteins at 23°C. Concentrations of abscisic acid and jasmonic acid increased up to 2- and 1.5-fold, respectively, in the cold-acclimated embryos. After 10 weeks at 4°C, the embryos stayed at pre-cotyledonary stage with 17.1% less DNA methylation and fewer storage substances than those at 23°C for 4 weeks, which developed cotyledons. This research provides new insights into mechanisms underlying the response of SEs to different culture temperatures and benefits method development for germplasm conservation in conifers.