Variations in protein concentration and nitrogen sources in different positions of grain in wheat

The distribution patterns of total protein and protein components in different layers of wheat grain were investigated using the pearling technique, and the sources of different protein components and pearling fractions were identified using (15)N isotope tracing methods. It was found that N absorbed from jointing to anthesis (JA) and remobilized to the grain after anthesis was the principal source of grain N, especially in the outer layer. For albumin and globulin, the amount of N absorbed during different stages all showed a decreasing trend from the surface layer to the center part. Whereas, for globulin and glutenin, the N absorbed after anthesis accounted for the main part indicating that for storage protein, the utilization of N assimilated after anthesis is greater than that of the stored N assimilated before anthesis. It is concluded that manipulation of the N application rate during different growth stages could be an effective approach to modulate the distribution of protein fractions in pearled grains for specific end-uses

Mechano-stimulated modifications in the chloroplast antioxidant system and proteome changes are associated with cold response in wheat

BACKGROUND: Mechanical wounding can cause morphological and developmental changes in plants, which may affect the responses to abiotic stresses. However, the mechano-stimulation triggered regulation network remains elusive. Here, the mechano-stimulation was applied at two different times during the growth period of wheat before exposing the plants to cold stress (5.6 °C lower temperature than the ambient temperature, viz., 5.0 °C) at the jointing stage. RESULTS: Results showed that mechano-stimulation at the Zadoks growth stage 26 activated the antioxidant system, and substantially, maintained the homeostasis of reactive oxygen species. In turn, the stimulation improved the electron transport and photosynthetic rate of wheat plants exposed to cold stress at the jointing stage. Proteomic and transcriptional analyses revealed that the oxidative stress defense, ATP synthesis, and photosynthesis-related proteins and genes were similarly modulated by mechano-stimulation and the cold stress. CONCLUSIONS: It was concluded that mechano-stimulated modifications of the chloroplast antioxidant system and proteome changes are related to cold tolerance in wheat. The findings might provide deeper insights into roles of reactive oxygen species in mechano-stimulated cold tolerance of photosynthetic apparatus, and be helpful to explore novel approaches to mitigate the impacts of low temperature occurring at critical developmental stages. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12870-015-0610-6) contains supplementary material, which is available to authorized users

Superior glucose metabolism supports NH4+ assimilation in wheat to improve ammonium tolerance

The use of slow-release fertilizers and seed-fertilizers cause localized high-ammonium (NH4+) environments in agricultural fields, adversely affecting wheat growth and development and delaying its yield. Thus, it is important to investigate the physiological responses of wheat and its tolerance to NH4+ stress to improve the adaptation of wheat to high NH4+ environments. In this study, the physiological mechanisms of ammonium tolerance in wheat (Triticum aestivum) were investigated in depth by comparative analysis of two cultivars: NH4+-tolerant Xumai25 and NH4+-sensitive Yangmai20. Cultivation under hydroponic conditions with high NH4+ (5 mM NH4+, AN) and nitrate (5 mM NO3-, NN), as control, provided insights into the nuanced responses of both cultivars. Compared to Yangmai20, Xumai25 displayed a comparatively lesser sensitivity to NH4+ stress, as evident by a less pronounced reduction in dry plant biomass and a milder adverse impact on root morphology. Despite similarities in NH4+ efflux and the expression levels of TaAMT1.1 and TaAMT1.2 between the two cultivars, Xumai25 exhibited higher NH4+ influx, while maintaining a lower free NH4+ concentration in the roots. Furthermore, Xumai25 showed a more pronounced increase in the levels of free amino acids, including asparagine, glutamine, and aspartate, suggesting a superior NH4+ assimilation capacity under NH4+ stress compared to Yangmai20. Additionally, the enhanced transcriptional regulation of vacuolar glucose transporter and glucose metabolism under NH4+ stress in Xumai25 contributed to an enhanced carbon skeleton supply, particularly of 2-oxoglutarate and pyruvate. Taken together, our results demonstrate that the NH4+ tolerance of Xumai25 is intricately linked to enhanced glucose metabolism and optimized glucose transport, which contributes to the robust NH4+ assimilation capacity

Hydrogen Peroxide and Abscisic Acid Mediate Salicylic Acid-Induced Freezing Tolerance in Wheat

Salicylic acid (SA) can induce plant resistance to biotic and abiotic stresses through cross talk with other signaling molecules, whereas the interaction between hydrogen peroxide (H2O2) and abscisic acid (ABA) in response to SA signal is far from clear. Here, we focused on the roles and interactions of H2O2 and ABA in SA-induced freezing tolerance in wheat plants. Exogenous SA pretreatment significantly induced freezing tolerance of wheat via maintaining relatively higher dark-adapted maximum photosystem II quantum yield, electron transport rates, less cell membrane damage. Exogenous SA induced the accumulation of endogenous H2O2 and ABA. Endogenous H2O2 accumulation in the apoplast was triggered by both cell wall peroxidase and membrane-linked NADPH oxidase. The pharmacological study indicated that pretreatment with dimethylthiourea (H2O2 scavenger) completely abolished SA-induced freezing tolerance and ABA synthesis, while pretreatment with fluridone (ABA biosynthesis inhibitor) reduced H2O2 accumulation by inhibiting NADPH oxidase encoding genes expression and partially counteracted SA-induced freezing tolerance. These findings demonstrate that endogenous H2O2 and ABA signaling may form a positive feedback loop to mediate SA-induced freezing tolerance in wheat

Investigation of Salt Tolerance Mechanisms across a Root Developmental Gradient in Almond Rootstocks

The intensive use of groundwater in agriculture under the current climate conditions leads to acceleration of soil salinization. Given that almond is a salt-sensitive crop, selection of salt-tolerant rootstocks can help maintain productivity under salinity stress. Selection for tolerant rootstocks at an early growth stage can reduce the investment of time and resources. However, salinity-sensitive markers and salinity tolerance mechanisms of almond species to assist this selection process are largely unknown. We established a microscopy-based approach to investigate mechanisms of stress tolerance in and identified cellular, root anatomical, and molecular traits associated with rootstocks exhibiting salt tolerance. We characterized three almond rootstocks: Empyrean-1 (E1), Controller-5 (C5), and Krymsk-86 (K86). Based on cellular and molecular evidence, our results show that E1 has a higher capacity for salt exclusion by a combination of upregulating ion transporter expression and enhanced deposition of suberin and lignin in the root apoplastic barriers, exodermis, and endodermis, in response to salt stress. Expression analyses revealed differential regulation of cation transporters, stress signaling, and biopolymer synthesis genes in the different rootstocks. This foundational study reveals the mechanisms of salinity tolerance in almond rootstocks from cellular and structural perspectives across a root developmental gradient and provides insights for future screens targeting stress response

Genome-Wide Identification and Expression Analysis of GATA Gene Family under Different Nitrogen Levels in <i>Arachis hypogaea</i> L.

Nitrogen, one of the essential elements, is a key determinant for improving peanut growth and yield. GATA zinc finger transcription factors have been found to be involved in regulation of nitrogen metabolism. However, a systematic characterization of the GATA gene family and patterns of their expression under different nitrogen levels remains elusive. In this study, a total of 45 GATA genes distributed among 17 chromosomes were identified in the peanut genome and classified into three subfamilies I, II and III with 26, 13 and 6 members, respectively, whose physicochemical characteristics, gene structures and conserved motifs were also analyzed. Furthermore, the optimal level of nitrogen fertilizer on the growth of peanut cultivar Yuhua 23 was determined by pod yield and value cost ratio from 2020 to 2022, and the results revealed that 150 kg hm−2 nitrogen was the best for cultivation of peanut Yuhua 23 because of its highest pod yield and relatively higher VCR of more than four. In addition, expression patterns of peanut GATA genes under different nitrogen levels were detected by real-time quantitative PCR and several GATA genes were significantly changed under a nitrogen level of 150 kg hm−2. Overall, the above results would be helpful for further understanding biological functions of the GATA gene family in cultivated peanut

Predicting the Protein Content of Grain in Winter Wheat with Meteorological and Genotypic Factors

Meteorological conditions including temperature, sunshine and precipitation during grain growth are the primary factors determining the variation of the protein content of grain (PC) in wheat. On the basis of field experiments, a simplified regression model was developed for predicting the PC in winter wheat. From stepwise regression analysis, it was found that the PC of high-protein cultivars was correlated with the difference between daily maximum and minimum temperatures (∆T) when ∆ T variation under the environment was significant, but with the interaction of mean temperature (Tmean) × total sunshine hours from anthesis to maturity (TSUN) under the environment with ∆ T variation less than 5%. In medium-protein cultivars, the PC was correlated with TSUN, and in low-protein cultivars, with the combination of Tmean, total rainfall from anthesis to maturity (TR) and TSUN. The climatic factors influencing PC were further quantified incorporating five genetic parameters. The ∆ T and TSUN were linearly correlated with PC, and Tmean was quadratically correlated with PC. The precipitation was linearly correlated with PC if it was less than 50mm, otherwise quadratically. The average root mean square error (RMSE) values of the estimated PC relative to the observed value were less than 7 percent, indicating a good fit between the estimated and observed PC. Thus, it is concluded that the present model can predict the PC of different winter wheat cultivars under various climate environments