Wheat Caryopses Research Articles

Adsorption of Ni(II) from Aqueous Media on Biodegradable Natural Polymers—Sarkanda Grass Lignin

Heavy metals are pollutants that pose a risk to living systems due to their high toxicity and ability to accumulate and contaminate. This study proposes an alternative approach to the static adsorption of Ni(II) from aqueous media using Sarkanda grass lignin crystals, the non-cellulosic aromatic component of biomass, as an adsorbent substrate. To determine the best experimental conditions, we conducted tests on several parameters, including the initial and adsorbent solution pH, the concentration of Ni(II) in the aqueous solution, the amount of adsorbent used, and the contact time at the interface. The lignin’s adsorption capacity was evaluated using the Freundlich and Langmuir models to establish equilibrium conditions. The Lagergren I and Ho–McKay II kinetic models were used to determine the adsorption mechanism based on surface analyses and biological parameters such as the number of germinated seeds, energy, and germination capacity in wheat caryopses (variety Glosa) incorporated in the contaminated lignin and in the filtrates resulting from phase separation. The results suggest that Sarkanda grass lignin is effective in adsorbing Ni(II) from aqueous media, particularly in terms of adsorbent/adsorbate dosage and interfacial contact time.

Changes in free amino acid and protein polymerization in wheat caryopsis and endosperm during filling after shading.

Over the past several decades, a decreasing trend in solar radiation has been observed during the wheat growing season. The effects of shade stress on grain yield formation have been extensively studied. However, little information on shade stress's effects on protein formation warrants further investigation. Two wheat cultivars were grown under three treatments, no shade as the control group (CK), shading from the joint to the anthesis stage (S1), and shading from the joint to the mature stage (S2), to investigate the effects of shade stress on the free amino acids of the caryopsis and endosperm and protein accumulation during grain filling. The dry mass of caryopsis and endosperm was significantly decreased under shade stress, whereas Glu, Ser, Ala, and Asp and protein relative content increased during grain filling. The observed increases in total protein in S1 and S2 were attributed to the increases in the SDS-isoluble and SDS-soluble protein extracts, respectively. S1 improved polymer protein formation, but S2 delayed the conversion of albumins and globulins into monomeric and polymeric proteins. Moreover, shade stress increased the proportion of SDS-unextractable polymeric protein, which represented an increase in the degree of protein polymerization. The polymerization of protein interrelations between protein components and accumulation in caryopsis and endosperm provided novel insights into wheat quality formation under shade stress.

Pericarp starch metabolism is associated with caryopsis development and endosperm starch accumulation in common wheat

The wheat pericarp is the main component of the caryopsis at the early development stage and ultimately converts into a tissue that covers the mature caryopsis. A large number of starch granules are accumulated in the pericarp, but the production of and the role of starch granules in caryopsis development remain- elusive. In the present study, the relationship between accumulated starch granules and starch metabolism-related genes in wheat pericarp was investigated using paraffin section observations, expression analysis, and mutant analysis. Starch synthesis is initiated before anthesis and is dependent on a sucrose uptake and conversion system similar to that in the endosperm. TaPTST2 is required to initiate the production of pericarp starch granules. Pericarp starch granules gradually disappeared at the filling stage with high expression levels of genes encoding β-amylase, sucrose-phosphate synthase, and sucrose-phosphate phosphatase. As a maternal tissue adjacent to the endosperm and embryo, the pericarp plays a temporary reservoir for excess nutrients delivered into the caryopsis during the early development stage and exported at the filling stage. The pericarp contributes to the development of the endosperm and embryo as well as the accumulation of endosperm starch. The metabolism of pericarp starch may affect the weight of the wheat caryopsis.

Visualized analysis of amino acids and organic acids in wheat caryopsis in response to multigenerational effects of elevated atmospheric CO2 concentration

The response of wheat to elevated atmospheric CO2 concentration (e[CO2]) within a single generation is being cumulatively studied, but multigenerational effects of e[CO2] on wheat is largely unknown. In this study, the emerging spatially resolved metabolomics was used to visualize the spatial distributions of amino acids and organic acids in wheat caryopsis exposed to multigenerational e[CO2]. These results showed that nine kinds of amino acids and three kinds of organic acids exhibited embryo-distribution pattern in wheat caryopsis under sequential atmospheric CO2 concentration (a[CO2]). Additionally, e[CO2] can induce nonuniformly spatial distribution of amino acids and organic acids. Further inspection of the differential accumulation of amino acids in embryo/endosperm under multigenerational e[CO2] exposure indicated that the abundance of valine, glutamine, glutamic acid and histidine in embryo was decreased by multigenerational e[CO2] exposure, whereas abundance of lysine, aspartic acid and glutamic acid in endosperm showed different trends. Multigenerational e[CO2] exposure decreased the abundance of ascorbic acid and cis-aconitic acid, regardless of regions, while increased the abundance of malic acid in endosperm. It was suggested that the long-term e[CO2] cause inconsistent changes in embryo and endosperm, which may lead to potential impacts on human dietary health and crop offspring vigor.

Preliminary Study on the Impact of Non-Thermal Plasma Activated Water on the Quality of Triticum aestivum L. cv. Glosa Sprouts

The present study aimed to investigate the effects of non-thermal plasma-activated water (PAW) on Triticum aestivum L. cv. Glosa sprouts. Two types of PAW were generated by exposing distilled water to a high-voltage electric discharge. Wheat caryopses were treated either with PAW1 (25 mg/L NO3−, 4 mg/L NO2−, and 6 mg/L H2O2) or PAW2 (35 mg/L NO3−, 5 mg/L NO2−, and 7.5 mg/L H2O2) for 8 days, with samples being collected at days 1, 2, 3, and 8. The germination rate, growth parameters, protein, photosynthetic pigments, total phenolic contents, antioxidant activity of free and bound phenolic fractions, and activity of antioxidant enzymes were evaluated. Both PAW1 and PAW2 had positive effects on Triticum aestivum L. cv. Glosa sprouts. PAW2 had a better impact on sprouts with respect to growth parameters, free phenolic content, and antioxidant activity of the free phenolic fraction (day 3), the accumulation of proteins, and photosynthetic pigments (day 8). In conclusion, exposure to PAW increases the quality of Triticum aestivum L. cv. Glosa sprouts. Further optimization of PAW treatment is required for the most favorable impact on the accumulation of biomass and health-promoting compounds in sprouts.

The Role of Resorcinolic Lipids of Caryopsis Surface in the Process of Cereal Infection by Rhizoctonia solani and Fusarium culmorum

Cereal caryopses are rich in 5-n-alk(en)ylresorcinols, antimicrobial compounds. In this paper, the correlation between the presence of resorcinolic lipids on the surface of cereal grains and the susceptibility of their seedlings to infection by Rhizoctonia solani or Fusarium culmorum was evaluated. The declines in length of both the roots and coleoptiles were observed in barley seedlings of Scarlett and Rabel cultivars grown from the wax-impoverished seeds infected with F92 and F93 strains of Rhizoctonia solani, respectively. Regarding wheat, R. solani F93 significantly reduced only the coleoptile growth. Resorcinolic lipids, being the mixture of homologues with C17–C25 carbon chains, were the only compounds washed off wheat caryopses by chloroform. Moreover, the better anti-Rhizoctonia solani F93 activity of 5-n-alk(en)ylresorcinols of wheat grains than that of rye caryopsis lipids was proven by the poisoned medium technique. Two saturated homologues (C21:0 and C23:0) were the most effective inhibitors of the mycelial growth of this fungus. Thus, the susceptibilities of barley and wheat seedlings to some fungal pathogens have been found to be related to the content and composition of 5-n-alk(en)ylresorcinols in the waxy layer of cereal grains, confirming the protective role of these compounds, during the early stages of cereal development.

RESEARCH ON OBTAINING LIQUID MYCELIA FROM PLEUROTUS SPP. STRAINS AND TESTING THEIR FRUITING POTENTIAL

The paper focuses on the obtaining biotechnology and in vitro propagation of edible and/or medicinal macromycetes mycelia from the genus Pleurotus in submerged cultures in order to produce the biological “seeding” material - spawn. The quality and biological purity of the spawn is critical to the success of mushroom production and productivity. Starting from stock cultures from the collection of the RDIVFG Vidra, the mother cultures were obtained, the biological material being represented by two strains of Pleurotus ostreatus and one strain of Pleurotus citrinopileatus, each of them being cultivated in PDB + K2HPO4 (1,5g/l), pH 6.5 medium at different stirring speeds (0/100/150 rpm). The submerged growing biomass was used to inoculate wheat caryopsis, that evolved into spawn after complete colonization. The lignocellulosic substrate was obtained from wheat straws with the addition of nutritional supplements (wheat and maize bran and sunflower middlings) and distributed in the polypropylene bags. Their yielding capacity was verified in the fruiting chamber of the laboratory micro-mushroom farm test facility.

Influence of Drought and Salt Stress on Durum Wheat Grain Quality and Composition: A Review.

Durum wheat is a staple crop for the Mediterranean diet because of its adaptability to environmental pressure and for its large use in cereal-based food products, such as pasta and bread, as a source of calories and proteins. Durum wheat whole grains are also highly valued for their peculiar amount of dietary fiber and minerals, as well as bioactive compounds of particular interest for their putative health-beneficial properties, including polyphenols, carotenoids, tocopherols, tocotrienols, and phytosterols. In Mediterranean environments, durum wheat is mostly grown under rainfed conditions, where the crop often experiences environmental stresses, especially water deficit and soil salinity that may induce a hyperosmotic stress. In particular, changes in C and N accumulation due to these abiotic conditions, during grain filling, can influence starch and storage protein amount and composition in durum wheat caryopsis, thus influencing yield and quality traits. Recent advancements regarding the influence of water deficit and salinity stress on durum wheat are critically discussed. In particular, a focus on stress-induced changes in (a) grain protein content and composition in relation to technological and health quality; (b) starch and dietary fiber accumulation and composition; (c) phytochemical composition; (d) health-related grain micronutrient accumulation, such as Fe and Zn.

The relationship between characteristics of root morphology and grain filling in wheat under drought stress.

Drought is a common yield limiting factor in wheat production and has become a significant threat to global food security. Root system is the organ responsible for water uptake from soil and root growth is closely associated with yield and quality of wheat. However, the relationship between morphological and structural characteristics of root growth and caryopsis enrichment in wheat under drought stress is unclear. In this study, two wheat cultivars (YM13 and YN19) were treated with drought from flowering to caryopsis maturity stage. The changes in morphological structure of roots and characteristics of endosperm enrichment were investigated. Drought stress significantly reduced the root length, plant height, root dry weight and aboveground parts dry weight, whereas the root-shoot ratio of YM13 and YN19 increased by 17.65% and 8.33% under drought stress, respectively. The spike length, spike weight, grains number per spike and 1,000-grains weight of mature wheat also significantly declined under drought stress. Meanwhile, the cross section structure of roots was changed with the enlargement of vascular cylinder and dense distribution of xylem vessels under drought stress. Additionally, drought stress affected the substance enrichment in wheat caryopses, decreasing starch accumulation and increasing protein accumulation of endosperm. Correlation analysis suggested that the root length was closely correlated with the relative areas of amyloplast (0.51) and protein body (0.70), and drought stress increased the correlation coefficient (0.79 and 0.78, respectively). While the root dry weight had a significantly positive correlation with the plant height and aboveground parts dry weight. The results can provide theoretical basis for root architecture optimization, water-saving and high-yield cultivation and quality improvement in wheat.

THE EFFICIENCY OF USING NITROGEN FERTILIZERS IN WHEAT CROP

Nitrogen has its undeniable role in increasing crop productivity and quality. However, used improperly, it can cause serious environmental damage. Increasing the efficiency of the use of chemical nitrogen fertilizers (NUE) is a goal of the future¸ necessary for a sustainable and competitive agriculture. The wheat crop studied is part of a long-term experiment, established in Lovrin in 1967. The experimental factors studied are: factor A - nitrogen, with the following graduations: N0, N30, N60, N90 and N120 and factor B - phosphorus, with the following graduations: P0, P40, P80, P120 and P160. From the combination of the two studied factors results 25 experimental variants, placed in the field according to the method of subdivided plots, in four repetitions. Chemical fertilizers with phosphorus - 46% superphosphate - were administered to the wheat crop in autumn and were incorporated under the basic plowing. Nitrogen fertilizers - 33.5% ammonium nitrate - were applied in fractions: 40% of the dose at start of vegetation, in the spring and 60% at straw elongation. The wheat culture is part of a three-year crop rotation - soybeans-wheat-corn. Following in rotation after soybeans, no nitrogen fertilizers were applied at the establishment of the crop. The variety studied is the Ciprian variety, created at SCDA Lovrin. For the evaluation of NUE, Plant N Uptake, Nitrogen Use Effciency and Partial Factor Productivity were analyzed in this paper. In the climatic conditions of the two experimental years, a distinctly significant positive correlation is established between the nitrogen dose administered and production, the value of the correlation coefficient being 0.56 **. Between the nitrogen dose, the protein content and the amount of protein per ha the correlation is very significant, with the following values ​​of the correlation coefficients: r = 0.96 *** (for protein) and r = 0.90 *** (for N uptake). Nitrogen use efficiency correlates negatively, very significantly, with the administered dose - r = -0.87 ***. This study also reveals the importance of phosphorus in the absorption and accumulation of nitrogen in wheat caryopsis. The amount of nitrogen accumulated increases with increasing dose of phosphorus, up to 80 kg ha-1, with the gradual reduction of the amount accumulated to high values ​​of phosphorus administered (120 kg ha-1 and 160 kg ha-1, respectively).

Synthesis and accumulation of amylase-trypsin inhibitors and changes in carbohydrate profile during grain development of bread wheat (Triticum aestivum L.)

BackgroundRecent studies indicate that amylase-trypsin inhibitors (ATIs) and certain carbohydrates referred to as FODMAPs (fermentable oligo-, di-, monosaccharides and polyols) play an important role in promoting wheat sensitivity. Hitherto, no study has investigated the accumulation of ATIs during the development of the wheat caryopsis. We collected caryopses of common wheat cv. ‘Arnold’ at eight different grain developmental stages to study compositional changes in ATI and FODMAP content.ResultsThe harvested caryopses were analysed for their size, protein and carbohydrate concentrations. ATIs were further characterized by MALDI-TOF MS, and their trypsin inhibition was evaluated by an enzymatic assay. The results showed that ATI accumulation started about 1 week after anthesis and subsequently increased steadily until physiological maturity. However, the biological activity of ATIs in terms of enzyme inhibition was not detectable before about 4 weeks after anthesis. Carbohydrate analysis revealed the abundance of short-chain fructans in early stages of grain development, whereas non-water-soluble carbohydrates increased during later developmental stages.ConclusionsThe results provide new insights into the complex metabolisms during grain filling and maturation, with particular emphasis on the ATI content as well as the inhibitory potential towards trypsin. The time lag between ATI accumulation and development of their biological activity is possibly attributed to the assembling of ATIs to dimers and tetramers, which seems to be crucial for their inhibitory potential.

Monitoring of changes in 5-n-alkylresorcinols during wheat seedling development.

For seven days of wheat growth, caryopsis remained the main source of 5-n-alkylresorcinols with C19 and/or C21 homolog as a main compound. Shoot contained small amount of these phenolic lipids; their average content was 3.23% of level obtained in the whole seedling. Moreover, 41.38% of resorcinolic lipids of seven-day-old shoot was accumulated in part of leaf covered by coleoptile. Interestingly, a removal of 1.07% of the primary pool of kernel alkylresorcinols by short-term washing (10s) of wheat seed with acetone before planting decreased their level only in seed of seven-day old seedling. Compared to the respective controls, this treatment did not affect the amount of these lipids in the green part of seedling that proved that de novo synthesis of 5-n-alkylresorcinols takes place in shoots. The very similar homolog profiles of these lipids in four- and seven-day-old shoots turned out to be markedly less diversified than those found in respective seed samples. Compared to the mature wheat caryopsis, the rise in the content of very-long-chain homologs was observed only in the oldest shoot. Their increased accumulation was probably connected with formation of cuticular layer providing the defensive barrier against various phytopathogens.

New insights into the mechanism of storage protein biosynthesis in wheat caryopsis under different nitrogen levels.

Effect of different nitrogen levels (0, 150, and 300kghm-2) at booting stage on storage protein biosynthesis and processing quality of wheat was investigated using microstructural and ultrastructural observation, RNA sequencing, and quality analysis in this study. The results showed that the storage protein genes encoding ω- and γ-gliadin and low molecular weight glutenin subunit were upregulated at N150, and the genes encoding α- or β-gliadin and avenin-like protein were upregulated at N300. Two nitrogen levels induced expression of some interesting regulating genes, such as USE1, STX1B_2_3, SEC23, SEC24, SEC61A, HSP A1_8, HSP20, and HSP90B/TRA1. These regulatory genes were enriched in the KEGG pathway protein export, SNARE interactions in vesicular transport, and protein processing in endoplasmic reticulum. The amount, morphology, and accumulation pattern of protein body in four different endosperm regions in developing caryopsis show different response to N150 and N300, of which N300 had greater influence than N150. N150 and N300 both enhanced the contents of protein components, endosperm fullness, grain hardness, and parameters of processing quality, with the latter showing a greater degree of influence. Contrary to the accumulation pattern of protein body, N300 reduced the ratio of the amount of starch granules to the area ratio of protein body to starch granule. Results suggested that the difference of different nitrogen levels affecting storage protein biosynthesis might be through affecting the expression of the encoding and regulating gene of storage protein.

Neural Visual Detection of Grain Weevil (Sitophilus granarius L.)

A significant part of cereal production is intended for agri-food processing, which implies a necessity to search for and implement modern storage systems for this product. Stored grain is exposed to many unfavorable factors, particularly caryopsis macro-damage caused mainly by grain weevil (Sitophilus granarius L.). This triggers a substantial decrease in the value of the stored material, thus resulting in serious economic losses. Due to this fact, it is necessary to take steps to effectively detect this pest’s presence when grain is delivered to storage facilities. The purpose of this work was to identify the representative physical characteristics of wheat caryopsis affected by grain weevil. An automated visual system was developed to ease the detection of damaged kernels and adult weevils. In order to obtain the empirical data, a decision was made to take advance of SKCS 4100 (the Perten Single Kernel Characterization System). The measurements obtained were used to build the training sets necessary in the process of ANN (artificial neural network) learning with digital neural classifiers. Next, a set of identifying neural models was created and verified, and then the optimal topology was selected. The utilitarian goal of the research was to support the decision-making process taking place during grain storage.

Changes in spatiotemporal protein and amino acid gradients in wheat caryopsis after N-topdressing

Wheat grain nitrogen content displays large variations within different pearling fractions of grains because of radial gradients in the protein content. We identified how spatiotemporal mechanisms regulate this. The protein gradients emerged clearly at 19 days after anthesis, with the highest N content in aleurone and seed coat, followed by outer endosperm, whereas the lowest was in middle and inner endosperm. Laser microdissection, qRT-PCR and LC–MS were used to dissect tissue from aleurone, outer endosperm, middle endosperm, inner endosperm and transfer cells, measure gene expression and levels of free and protein-bound amino acids, respectively. The results showed that different FAA transportation pathways worked in parallel during grain filling stage while the grain protein gradient did not follow spatial expression of storage proteins. Additionally, two nitrogen (N) topdressing timings were conducted, either at the emergence of top third leaf (standard timing) or top first leaf (delayed timing), finding that delayed N topdressing enhanced both amino acids supply and protein synthesis capacity. The results provide insight into protein synthesis and amino acid transport pathways in endosperm and suggest targets for the enhancement of specialty pearled wheat with higher quality.

Graphene oxide effects in early ontogenetic stages of Triticum aestivum L. seedlings

Nanomaterials are being used increasingly in various areas such as electronic devices manufacture, medicine, mechanical devices production, and even food industry. Therefore, the evaluation of their toxicity is mandatory. Graphene oxide (GO) has been shown to have both positive as well as negative impact on different crop plants, depending on species, dose, and duration of exposure. The current study evaluated the impact of GO sheets at different concentrations (500, 1000 and 2000 mg/L) on physiological, biochemical and genetic levels to determine the possible toxic action. Wheat caryopses were treated with GO for 48 h and 7 days. The germination rate and roots elongation decreased in a dose-response manner, except the sample treated with GO at a concentration of 1000 mg/L. Mitotic index has ascendant trend; its increase may be due to the accumulation of prophases GO induced significant accumulation of the cells with aberrations, their presence suggests a clastogenic/aneugenic effect of these carbon nanomaterials. Regarding enzymatic and non-enzymatic antioxidant system defence, the activity varied depending on the dose of GO. Thus, chlorophyll a pigments content decreased significantly at high dose (2000 mg/L), while the carotenoid pigments had lower content at 500 mg/L of GO, and no statistical difference encountered in case of chlorophyll b amount. The antioxidant enzyme activity (CAT, POD, and SOD) was higher at low dose of GO, indicating the presence of oxidative stress generated as a response to the GO treatment. Also, the free radical scavenging activity of the polyphenolic compounds was enhanced upon GO exposure. The GO accumulation has been identified by transmission electron microscopy only at plumules level, near the intercellular space.

The antimicrobial properties of the puroindolines, a review.

Antimicrobial proteins, and especially antimicrobial peptides (AMPs) hold great promise in the control of animal and plant diseases with low risk of pathogen resistance. The two puroindolines, a and b, from wheat control endosperm softness of the wheat caryopsis (grain), but have also been shown to inhibit the growth and kill various bacteria and fungi, while showing little toxicity to erythrocytes. Puroindolines are small (~ 13kDa) amphipathic proteins with a characteristic tryptophan-rich domain (TRD) that is part of an 18 or 19 amino acid residue loop subtended by a disulfide bond. This review presents a brief history of the puroindolines, their physical-chemical characteristics, their interaction with lipids and membranes, and their activity as antimicrobial proteins and AMPs. In this latter context, the use of the TRDs of puroindoline a and b in puroindoline AMP function is reviewed. The activity of puroindoline a and b and their AMPs appear to act through similar but somewhat different modes, which may involve membrane binding, membrane disruption and ion channel formation, and intra-cellular nucleic acid binding and metabolic disruption. Natural and synthetic mutants have identified key elements of the puroindolines for antimicrobial activity.

Infection pathways and penetration modes of Fusarium langsethiae

Fusarium langsethiae is one of the common Fusarium species infecting small grain cereals in the Nordic region and the UK. It is usually described as a weak pathogen, and with a strong preference for oats, although no studies have yet addressed the explanations for this at the microscopic level. Using microscope techniques we have studied the early steps of colonization of oat and wheat grain by F. langsethiae particularly addressing the role of pollen in the infection process and the fungal ability to penetrate plant cell wall. The aim was to better understand its non-aggressive colonization picture and why oat is preferred over wheat as a host. Spray inoculated oat and wheat plants were scored for fungal progression at 3, 6, 10 and 14 days post inoculation (dpi) using light microscopy and scanning electron microscopy (SEM). Fungal hyphae entered the grain at the apex, or along the sides in the overlapping zone between palea wings and lemma, then spread basipetally and laterally, with a clear directional growth towards the caryopsis. Hyphal growth was clearly aided by the presence of pollen. On oat proliferating hyphae developed a variety of penetration structures on all internal surfaces. F. langsethiae infection on wheat progressed along the same routes, however slower and overall with less hyphal mass. Interestingly, hyphae closely associated to the wheat caryopsis seemed to undergo degradation, and profuse conidiation was observed at 14 dpi. Explanations for the differences in F. langsethiae colonization of oat versus wheat are suggested in light of the results.

Comparison of Endosperm Amyloplast Development and Degradation in Waxy and Non-waxy Wheat

The waxy wheat shows special starch quality due to high amylopectin content. However, little information is available concerning the development and degradation of amyloplast from waxy wheat endosperm. To address this problem, waxy wheat variety, Yangnuo 1, and a non-waxy wheat variety, Yangmai 13, were chosen to investigate the development and degradation of endosperm amyloplast during wheat caryopsis development and germination stage respectively using histochemical staining and light microscopy. Changes of morphology, the soluble sugar and total starch content were indistinguishable in the process of caryopsis development of two wheat varieties. The developing endosperm of non-waxy was stained blue-black by I2-KI while the endosperm of waxy wheat was stained reddish-brown, but the pericarp of waxy and non-waxy wheat was stained blue-black. In contrast to nonwaxy wheat, endosperm amyloplast of waxy wheat had better development status and higher proportion of small amyloplast. During seed germination many small dissolution pores appeared on the surface of endosperm amyloplast and the pores became bigger and deeper until amyloplast disintegrated. The rate of degradation of waxy wheat endosperm amyloplast was faster than non-waxy wheat. Our results may also be helpful to the use of waxy starch in food and nonfood industry.

Novel Insights into miRNA Regulation of Storage Protein Biosynthesis during Wheat Caryopsis Development under Drought Stress.

Drought stress is a significant abiotic stress factor that affects wheat yield and quality. MicroRNA (miRNA) plays an important role in regulating caryopsis development in response to drought stress. However, little is known about the expression characteristics of miRNAs and how they regulate protein accumulation in wheat caryopsis under drought stress. To address this, two small RNA libraries of wheat caryopsis under control and drought stress conditions were constructed and sequenced. A total of 125 miRNAs were identified in the two samples, of which 110 were known and 15 were novel. A total of 1,981 miRNA target genes were predicted and functional annotations were obtained from various databases for 1,641 of them. Four miRNAs were identified as differential expression under drought stress, and the expression patterns of three of them were consistent with results obtained by reverse transcription polymerase chain reaction (RT-PCR) and reverse transcription quantitative polymerase chain reaction (RT-qPCR). Moreover, three miRNA-target pairs showed negative regulation tendency, as revealed by RT-qPCR. Functional enrichment and pathway analysis revealed that four pathways might be involved in storage protein biosynthesis. Furthermore, drought stress significantly increased the accumulation of protein bodies and protein content in wheat endosperm. In summary, our findings suggest that drought stress may enhance storage protein by regulating the expression of miRNAs and their target genes.