Genetic diversity and population structure of wheat landraces in Southern Winter Wheat Region of China.

BACKGROUND: Wheat landraces are considered a valuable source of genetic diversity for breeding programs. It is useful to evaluate the genetic diversity in breeding studies such as marker-assisted selection (MAS), genome-wide association studies (GWAS), and genomic selection. In addition, constructing a core germplasm set that represents the genetic diversity of the entire variety set is of great significance for the efficient conservation and utilization of wheat landrace germplasms. RESULTS: To understand the genetic diversity in wheat landrace, 2,023 accessions in the Jiangsu Provincial Crop Germplasm Resource Bank were used to explore the molecular diversity and population structure using the Illumina 15 K single nucleotide polymorphism (SNP) chip. These accessions were divided into five subpopulations based on population structure, principal coordinate and kinship analysis. A significant variation was found within and among the subpopulations based on the molecular variance analysis (AMOVA). Subpopulation 3 showed more genetic variability based on the different allelic patterns (Na, Ne and I). The M strategy as implemented in MStratv 4.1 software was used to construct the representative core collection. A core collection with a total of 311 accessions (15.37%) was selected from the entire landrace germplasm based on genotype and 12 different phenotypic traits. Compared to the initial landrace collections, the core collection displayed higher gene diversity (0.31) and polymorphism information content (PIC) (0.25), and represented almost all phenotypic variation. CONCLUSIONS: A core collection comprising 311 accessions containing 100% of the genetic variation in the initial population was developed. This collection provides a germplasm base for effective management, conservation, and utilization of the variation in the original set.

Physiological and genomic insights into a psychrotrophic drought-tolerant bacterial consortium for crop improvement in cold, semiarid regions.

The agricultural land in the Indian Himalayan region (IHR) is susceptible to various spells of snowfall, which can cause nutrient leaching, low temperatures, and drought conditions. The current study, therefore, sought an indigenous psychrotrophic plant growth-promoting (PGP) bacterial inoculant with the potential to alleviate crop productivity under cold and drought stress. Psychrotrophic bacteria preisolated from the night-soil compost of the Lahaul Valley of northwestern Himalaya were screened for phosphate (P) and potash (K) solubilization, nitrogen fixation, indole acetic acid (IAA) production, siderophore and HCN production) in addition to their tolerance to drought conditions for consortia development. Furthermore, the effects of the selected consortium on the growth and development of wheat (Triticum aestivum L.) and maize (Zea mays L.) were assessed in pot experiments under cold semiarid conditions (50 % field capacity). Among 57 bacteria with P and K solubilization, nitrogen fixation, IAA production, siderophore and HCN production, Pseudomonas protegens LPH60, Pseudomonas atacamensis LSH24, Psychrobacter faecalis LUR13, Serratia proteamaculans LUR44, Pseudomonas mucidolens LUR70, and Glutamicibacter bergerei LUR77 exhibited tolerance to drought stress (-0.73 MPa). The colonization of wheat and maize seeds with these drought-tolerant PGP strains resulted in a germination index >150, indicating no phytotoxicity under drought stress. Remarkably, a particular strain, Pseudomonas sp. LPH60 demonstrated antagonistic activity against three phytopathogens Ustilago maydis, Fusarium oxysporum, and Fusarium graminearum. Treatment with the consortium significantly increased the foliage (100 % and 160 %) and root (200 % and 133 %) biomasses of the wheat and maize plants, respectively. Furthermore, whole-genome sequence comparisons of LPH60 and LUR13 with closely related strains revealed genes associated with plant nutrient uptake, phytohormone synthesis, siderophore production, hydrogen cyanide (HCN) synthesis, volatile organic compound production, trehalose and glycine betaine transport, cold shock response, superoxide dismutase activity, and gene clusters for nonribosomal peptide synthases and polyketide synthetases. With their PGP qualities, biocontrol activity, and ability to withstand environmental challenges, the developed consortium represents a promising cold- and drought-active PGP bioinoculant for cereal crops grown in cold semiarid regions.

Genetic Basis Identification of a NLR Gene, TaRGA5-like, That Confers Partial Powdery Mildew Resistance in Wheat SJ106.

Wheat powdery mildew is an important fungal disease that seriously jeopardizes wheat production, which poses a serious threat to food safety. SJ106 is a high-quality, disease-resistant spring wheat variety; this disease resistance is derived from Wheat-wheatgrass 33. In this study, the powdery mildew resistance genes in SJ106 were located at the end of chromosome 6DS, a new disease resistance locus tentatively named PmSJ106 locus. This interval was composed of a nucleotide-binding leucine-rich repeat (NLR) gene cluster containing 19 NLR genes. Five NLRs were tandem duplicated genes, and one of them (a coiled coil domain-nucleotide binding site-leucine-rich repeat (CC-NBS-LRR; CNL) type gene, TaRGA5-like) expressed 69-836-fold in SJ106 compared with the susceptible control. The genome DNA and cDNA sequences of TaRGA5-like were amplified from SJ106, which contain several nucleotide polymorphisms in LRR regions compared with susceptible individuals and Chinese Spring. Overexpression of TaRGA5-like significantly increased resistance to powdery mildew in susceptible receptor wheat Jinqiang5. However, Virus induced gene silence (VIGS) of TaRGA5-like resulted in only a small decrease of SJ106 in disease resistance, presumably compensated by other NLR duplicated genes. The results suggested that TaRGA5-like confers partial powdery mildew resistance in SJ106. As a member of the PmSJ106 locus, TaRGA5-like functioned together with other NLR duplicated genes to improve wheat resistance to powdery mildew. Wheat variety SJ106 would become a novel and potentially valuable germplasm for powdery mildew resistance.

Root Hairs: An under-explored target for sustainable cereal crop production.

To meet the demands of a rising human population, plant breeders will need to develop improved crop varieties that maximize yield in the face of increasing pressure on crop production. Historically, the optimization of crop root architecture has represented a challenging breeding target due to the inaccessibility of the root systems. Root hairs, single cell projections from the root epidermis, are perhaps the most overlooked component of root architecture traits. Root hairs play a central role in facilitating water, nutrient uptake, and soil cohesion. Current root hair architectures may be suboptimal under future agricultural production regimes, coupled with an increasingly variable climate. Here, we review the genetic control of root hair development in the world's three most important crops: rice, maize and wheat, and highlight conservation of gene function between monocots and the model dicot species Arabidopsis. Advances in genomic techniques including Gene-Editing combined with traditional plant breeding methods have the potential to overcome many inherent issues associated with the design of improved root hair architectures. Ultimately, this will enable detailed characterization of the effects of contrasting root hair morphology strategies on crop yield and resilience, and the development of new varieties better adapted to deliver future food security.

Analysis of the Effects of the Vrn-1 and Ppd-1 Alleles on Adaptive and Agronomic Traits in Common Wheat (Triticum aestivum L.).

Wheat heading time is primarily governed by two loci: VRN-1 (response to vernalization) and PPD-1 (response to photoperiod). Five sets of near-isogenic lines (NILs) were studied with the aim of investigating the effect of the aforementioned genes on wheat vegetative period duration and 14 yield-related traits. Every NIL was sown in the hydroponic greenhouse of the Institute of Cytology and Genetics, SB RAS. To assess their allelic composition at the VRN-1 and PPD-1 loci, molecular markers were used. It was shown that HT in plants with the Vrn-A1vrn-B1vrn-D1 genotype was reduced by 29 and 21 days (p < 0.001) in comparison to HT in plants with the vrn-A1Vrn-B1vrn-D1 and the vrn-A1vrn-B1Vrn-D1 genotypes, respectively. In our study, we noticed a decrease in spike length as well as spikelet number per spike parameter for some NIL carriers of the Vrn-A1a allele in comparison to carriers of the Vrn-B1 allele. PCA revealed three first principal components (PC), together explaining more than 70% of the data variance. Among the studied genetic traits, the Vrn-A1a and Ppd-D1a alleles showed significant correlations with PCs. Regarding genetic components, significant correlations were calculated between PC3 and Ppd-B1a (-0.26, p < 0.05) and Vrn-B1 (0.57, p < 0.05) alleles. Thus, the presence of the Vrn-A1a allele affects heading time, while Ppd-D1a is associated with plant height reduction.

Contribution of Antioxidant System Components to the Long-Term Physiological and Protective Effect of Salicylic Acid on Wheat under Salinity Conditions.

Salicylic acid (SA) plays a crucial role in regulating plant growth and development and mitigating the negative effects of various stresses, including salinity. In this study, the effect of 50 µM SA on the physiological and biochemical parameters of wheat plants under normal and stress conditions was investigated. The results showed that on the 28th day of the growing season, SA pretreatment continued to stimulate the growth of wheat plants. This was evident through an increase in shoot length and leaf area, with the regulation of leaf blade width playing a significant role in this effect. Additionally, SA improved photosynthesis by increasing the content of chlorophyll a (Chl a) and carotenoids (Car), resulting in an increased TAP (total amount of pigments) index in the leaves. Furthermore, SA treatment led to a balanced increase in the levels of reduced glutathione (GSH) and oxidized glutathione (GSSG) in the leaves, accompanied by a slight but significant accumulation of ascorbic acid (ASA), hydrogen peroxide (H2O2), proline, and the activation of glutathione reductase (GR) and ascorbate peroxidase (APX). Exposure to salt stress for 28 days resulted in a reduction in length and leaf area, photosynthetic pigments, and GSH and ASA content in wheat leaves. It also led to the accumulation of H2O2 and proline and significant activation of GR and APX. However, SA pretreatment exhibited a long-term growth-stimulating and protective effect under stress conditions. It significantly mitigated the negative impacts of salinity on leaf area, photosynthetic pigments, proline accumulation, lipid peroxidation, and H2O2. Furthermore, SA reduced the salinity-induced depletion of GSH and ASA levels, which was associated with the modulation of GR and APX activities. In small-scale field experiments conducted under natural growing conditions, pre-sowing seed treatment with 50 µM SA improved the main indicators of grain yield and increased the content of essential amino acids in wheat grains. Thus, SA pretreatment can be considered an effective approach for providing prolonged protection to wheat plants under salinity and improving grain yield and quality.

Comprehensive identification, characterization and expression analysis of genes underpinning heat acclimatization in Triticum durum and Aegilops tauschii.

Wheat (Triticum aestivum L.) is an important cereal crop cultivated and consumed worldwide. Global warming-induced escalation of temperature during the seedling and grain-filling phase adversely affects productivity. To survive under elevated temperatures, most crop plants develop natural mechanisms at molecular level by activating heat shock proteins. However, other heat stress-related proteins like heat acclimatization (HA) proteins are documented in hexaploid wheat but have not been explored in detail in its diploid and tetraploid progenitors, which might help to overcome elevated temperature regimes for short periods. Our study aims to explore the potential HA genes in progenitors Triticum durum and Aegilops tauschii that perform well at higher temperatures. Seven genes were identified and phylogenetically classified into three families: K homology (KH), Chloroplast protein-enhancing stress tolerance (CEST), and heat-stress-associated 32 kDa (HSA32). Protein-protein interaction network revealed partner proteins that aid mRNA translation, protein refolding, and reactive species detoxification. Syntenic analysis displayed highly conserved relationships. RT-qPCR-based expression profiling revealed HA genes to exhibit diverse and dynamic patterns under high-temperature regimes, suggesting their critical role in providing tolerance to heat stress. The present study furnishes genetic landscape of HA genes that might help in developing climate-resilient wheat with higher acclimatization potential.

Mapping QTLs for adult-plant resistance to powdery mildew and stripe rust using a recombinant inbred line population derived from cross Qingxinmai × 041133.

A recombinant inbred line (RIL) population derived from wheat landrace Qingxinmai and breeding line 041133 exhibited segregation in resistance to powdery mildew and stripe rust in five and three field tests, respectively. A 16K genotyping by target sequencing (GBTS) single-nucleotide polymorphism (SNP) array-based genetic linkage map was used to dissect the quantitative trait loci (QTLs) for disease resistance. Four and seven QTLs were identified for adult-plant resistance (APR) against powdery mildew and stripe rust. QPm.caas-1B and QPm.caas-5A on chromosomes 1B and 5A were responsible for the APR against powdery mildew in line 041133. QYr.caas-1B, QYr.caas-3B, QYr.caas-4B, QYr.caas-6B.1, QYr.caas-6B.2, and QYr.caas-7B detected on the five B-genome chromosomes of line 041133 conferred its APR to stripe rust. QPm.caas-1B and QYr.caas.1B were co-localized with the pleiotropic locus Lr46/Yr29/Sr58/Pm39/Ltn2. A Kompetitive Allele Specific Polymorphic (KASP) marker KASP_1B_668028290 was developed to trace QPm/Yr.caas.1B. Four lines pyramiding six major disease resistance loci, PmQ, Yr041133, QPm/Yr.caas-1B, QPm.caas-2B.1, QYr.caas-3B, and QPm.caas-6B, were developed. They displayed effective resistance against both powdery mildew and stripe rust at the seedling and adult-plant stages.

Identification and characterization of the CRK gene family in the wheat genome and analysis of their expression profile in response to high temperature-induced male sterility.

Cysteine-rich receptor-like kinases (CRKs) play many important roles during plant development, including defense responses under both biotic and abiotic stress, reactive oxygen species (ROS) homeostasis, callose deposition and programmed cell death (PCD). However, there are few studies on the involvement of the CRK family in male sterility due to heat stress in wheat (Triticum aestivum L.). In this study, a genome-wide characterization of the CRK family was performed to investigate the structural and functional attributes of the wheat CRKs in anther sterility caused by heat stress. A total of 95 CRK genes were unevenly distributed on 18 chromosomes, with the most genes distributed on chromosome 2B. Paralogous homologous genes with Ka/Ks ratios less than 1 may have undergone strong purifying selection during evolution and are more functionally conserved. The collinearity analysis results of CRK genes showed that wheat and Arabidopsis (A. thaliana), foxtail millet, Brachypodium distachyon (B. distachyon), and rice have three, 12, 15, and 11 pairs of orthologous genes, respectively. In addition, the results of the network interactions of genes and miRNAs showed that five miRNAs were in the hub of the interactions map, namely tae-miR9657b-5p, tae-miR9780, tae-miR9676-5p, tae-miR164, and tae-miR531. Furthermore, qRT-PCR validation of the six TaCRK genes showed that they play key roles in the development of the mononuclear stage anthers, as all six genes were expressed at highly significant levels in heat-stressed male sterile mononuclear stage anthers compared to normal anthers. We hypothesized that the TaCRK gene is significant in the process of high-temperature-induced sterility in wheat based on the combination of anther phenotypes, paraffin sections, and qRT-PCR data. These results improve our understanding of their relationship.

Deacclimation and reacclimation processes in winter wheat: novel perspectives from time-series transcriptome analysis.

Winter wheat achieves freezing tolerance (FT) through cold acclimation (CA) - a process which is induced by low positive temperatures in autumn. The increasing occurrences of temperature fluctuations in winter lead to deacclimation (DEA), causing premature loss of FT, and the cultivars capable of reacclimation (REA) are more likely to survive the subsequent cold spells. The genetic mechanisms of DEA and REA remain poorly understood, necessitating further research to bolster climate resilience in winter wheat. Here, we selected two winter wheat genotypes with contrasting levels of FT and conducted a ten-week-long experiment imitating low-temperature fluctuations after CA under controlled conditions. Crown and leaf tissue samples for RNA-sequencing were collected at CA, DEA, and REA time-points. It is the first transcriptomic study covering both short- and long-term responses to DEA and REA in winter wheat. The study provides novel knowledge regarding CA, DEA, and REA and discusses the gene expression patterns conferring FT under temperature fluctuations. The freezing-tolerant genotype "Lakaja DS" showed elevated photosynthetic activity in leaf tissue and upregulated cryoprotective protein-encoding genes in crowns after CA when compared to the freezing-susceptible "KWS Ferrum". "Lakaja DS" also expressed cold acclimation-associated transcripts at a significantly higher level after 1 week of DEA. Following REA, "Lakaja DS" continued to upregulate dehydrin-related genes in crowns and exhibited significantly higher expression of chitinase transcripts in leaves, when compared to "KWS Ferrum". The findings of this study shed light on the genetic mechanisms governing DEA and REA in winter wheat, thus addressing the gaps in knowledge regarding FT under low-temperature fluctuations. The identified genes should be further examined as potential molecular markers for breeding strategies focused on developing freezing-tolerant winter-type crops. Publicly available datasets generated in this study are valuable resources for further research into DEA and REA, contributing towards the enhancement of winter wheat under global climate change.

Salicylic acid and Tocopherol improve wheat (Triticum aestivum L.) Physio-biochemical and agronomic features grown in deep sowing stress: a way forward towards sustainable production.

BACKGROUND: The rate of germination and other physiological characteristics of seeds that are germinating are impacted by deep sowing. Based on the results of earlier studies, conclusions were drawn that deep sowing altered the physio-biochemical and agronomic characteristics of wheat (Triticum aestivum L.). RESULTS: In this study, seeds of wheat were sown at 2 (control) and 6 cm depth and the impact of exogenously applied salicylic acid and tocopherol (Vitamin-E) on its physio-biochemical and agronomic features was assessed. As a result, seeds grown at 2 cm depth witnessed an increase in mean germination time, germination percentage, germination rate index, germination energy, and seed vigor index. In contrast, 6 cm deep sowing resulted in negatively affecting all the aforementioned agronomic characteristics. In addition, deep planting led to a rise in MDA, glutathione reductase, and antioxidants enzymes including APX, POD, and SOD concentration. Moreover, the concentration of chlorophyll a, b, carotenoids, proline, protein, sugar, hydrogen peroxide, and agronomic attributes was boosted significantly with exogenously applied salicylic acid and tocopherol under deep sowing stress. CONCLUSIONS: The results of the study showed that the depth of seed sowing has an impact on agronomic and physio-biochemical characteristics and that the negative effects of deep sowing stress can be reduced by applying salicylic acid and tocopherol to the leaves.

Features of the Effect of Quercetin on Different Genotypes of Wheat under Hypoxia.

Hypoxia is one of the common abiotic stresses that negatively affects the development and productivity of agricultural crops. Quercetin is used to protect plants from oxidative stress when exposed to environmental stressors. O2 deficiency leads to impaired development and morphometric parameters in wheat varieties Orenburgskaya 22 (Triticum aestivum L.) and varieties Zolotaya (Triticum durum Desf.). Cytological analysis revealed various types of changes in the cytoplasm under conditions of hypoxia and treatment with quercetin. The most critical changes in the cytoplasm occur in the Zolotaya variety during pretreatment with quercetin followed by hypoxia, and in the Orenburgskaya 22 variety during hypoxia. Quercetin has a protective effect only on the Orenburgskaya 22 variety, and also promotes a more effective recovery after exposure to low O2 content. Hypoxia causes an increase in reactive oxygen species and activates the antioxidant system. It has been shown that the most active components of the antioxidant system in the Orenburgskaya 22 variety are MnSOD and Cu/ZnSOD, and in the Zolotaya variety GSH. We have shown that quercetin provides resistance only to the wheat genotype Orenburgskaya 22, as a protective agent against abiotic stress, which indicates the need for a comprehensive study of the effects of exogenous protectors before use in agriculture.

The Evaluation of a Long-Term Experiment on the Relationships between Weather, Nitrogen Fertilization, Preceding Crop, and Winter Wheat Grain Yield on Cambisol.

In this paper, a sequence (1979-2022) of a long-term trial established in Lukavec in 1956 (Czech Republic) focusing on the effect of weather, various nitrogen (N) fertilization methods (control, PK, N1PK, N2PK, and N3PK) and preceding crops (cereals, legumes, and oil plants) on winter wheat grain yield is presented. The weather significantly changed at the site of the long-term trial. While the trend in the mean temperature significantly increased, precipitation did not change significantly over the long term. Four relationships between weather and grain yield were evaluated to be significant: (a) the mean temperature in February (r = -0.4) and the precipitation in (b) February (r = -0.4), (c) March (r = -0.4), and (d) May (r = 0.5). The yield trends for all the fertilizer treatments increased, including the unfertilized control. The N3PK treatment provided the highest mean grain yields, while the unfertilized control had the lowest yields. Comparing the preceding crops, the highest yields were harvested when the wheat followed the legumes. On the other hand, the cereals were evaluated as the least suitable preceding crop in terms of grain yield. According to the linear-plateau model, the optimal nitrogen (N) dose for modern wheat varieties, following legumes and under the trial's soil climate conditions, was 131 kg ha-1 N, corresponding to a mean grain yield of 8.2 t ha-1.

Genome-Wide Identification and Expression Profiling of the ABF Transcription Factor Family in Wheat (Triticum aestivum L.).

Members of the abscisic acid (ABA)-responsive element (ABRE) binding factor (ABF) and ABA-responsive element binding protein (AREB) families play essential roles in the regulation of ABA signaling pathway activity and shape the ability of plants to adapt to a range of stressful environmental conditions. To date, however, systematic genome-wide analyses focused on the ABF/AREB gene family in wheat are lacking. Here, we identified 35 ABF/AREB genes in the wheat genome, designated TaABF1-TaABF35 according to their chromosomal distribution. These genes were further classified, based on their phylogenetic relationships, into three groups (A-C), with the TaABF genes in a given group exhibiting similar motifs and similar numbers of introns/exons. Cis-element analyses of the promoter regions upstream of these TaABFs revealed large numbers of ABREs, with the other predominant elements that were identified differing across these three groups. Patterns of TaABF gene expansion were primarily characterized by allopolyploidization and fragment duplication, with purifying selection having played a significant role in the evolution of this gene family. Further expression profiling indicated that the majority of the TaABF genes from groups A and B were highly expressed in various tissues and upregulated following abiotic stress exposure such as drought, low temperature, low nitrogen, etc., while some of the TaABF genes in group C were specifically expressed in grain tissues. Regulatory network analyses revealed that four of the group A TaABFs (TaABF2, TaABF7, TaABF13, and TaABF19) were centrally located in protein-protein interaction networks, with 13 of these TaABF genes being regulated by 11 known miRNAs, which play important roles in abiotic stress resistance such as drought and salt stress. The two primary upstream transcription factor types found to regulate TaABF gene expression were BBR/BPC and ERF, which have previously been reported to be important in the context of plant abiotic stress responses. Together, these results offer insight into the role that the ABF/AREB genes play in the responses of wheat to abiotic stressors, providing a robust foundation for future functional studies of these genes.

GWAS in a Collection of Bulgarian Old and Modern Bread Wheat Accessions Uncovers Novel Genomic Loci for Grain Protein Content and Thousand Kernel Weight.

Genetic enhancement of grain production and quality is a priority in wheat breeding projects. In this study, we assessed two key agronomic traits-grain protein content (GPC) and thousand kernel weight (TKW)-across 179 Bulgarian contemporary and historic varieties and landraces across three growing seasons. Significant phenotypic variation existed for both traits among genotypes and seasons, and no discernible difference was evident between the old and modern accessions. To understand the genetic basis of the traits, we conducted a genome-wide association study with MLM using phenotypic data from the crop seasons, best linear unbiased estimators, and genotypic data from the 25K Infinium iSelect array. As a result, we detected 16 quantitative trait nucleotides (QTNs) associated with GPC and 15 associated with TKW, all of which passed the false discovery rate threshold. Seven loci favorably influenced GPC, resulting in an increase of 1.4% to 8.1%, while four loci had a positive impact on TKW with increases ranging from 1.9% to 8.4%. While some loci confirmed previously published associations, four QTNs linked to GPC on chromosomes 2A, 7A, and 7B, as well as two QTNs related to TKW on chromosomes 1B and 6A, may represent novel associations. Annotations for proteins involved in the senescence-associated nutrient remobilization and in the following buildup of resources required for seed germination have been found for selected putative candidate genes. These include genes coding for storage proteins, cysteine proteases, cellulose-synthase, alpha-amylase, transcriptional regulators, and F-box and RWP-RK family proteins. Our findings highlight promising genomic regions for targeted breeding programs aimed at improving grain yield and protein content.

Temperature fluctuation in soil alters the nanoplastic sensitivity in wheat.

Despite the wide acknowledgment that plastic pollution and global warming have become serious agricultural concerns, their combined impact on crop growth remains poorly understood. Given the unabated megatrend, a simulated soil warming (SWT, +4 °C) microcosm experiment was carried out to provide a better understanding of the effects of temperature fluctuations on wheat seedlings exposed to nanoplastics (NPs, 1 g L-1 61.71 ± 0.31 nm polystyrene). It was documented that SWT induced oxidative stress in wheat seedlings grown in NPs-contaminated soil, with an 85.56 % increase in root activity, while decreasing plant height, fresh weight, and leaf area by 8.72 %, 47.68 %, and 15.04 % respectively. The SWT also resulted in reduced photosynthetic electron-transfer reaction and Calvin-Benson cycle in NPs-treated plants. Under NPs, SWT stimulated the tricarboxylic acid (TCA) metabolism and bio-oxidation process. The decrease in photosynthesis and the increase in respiration resulted in an 11.94 % decrease in net photosynthetic rate (Pn). These results indicated the complicated interplay between climate change and nanoplastic pollution in crop growth and underscored the potential risk of nanoplastic pollution on crop production in the future climate.

QTL mapping for the flag leaf-related traits using RILs derived from Trititrigia germplasm line SN304 and wheat cultivar Yannong15 in multiple environments.

BACKGROUND: Developing and enriching genetic resources plays important role in the crop improvement. The flag leaf affects plant architecture and contributes to the grain yield of wheat (Triticum aestivum L.). The genetic improvement of flag leaf traits faces problems such as a limited genetic basis. Among the various genetic resources of wheat, Thinopyrum intermedium has been utilized as a valuable resource in genetic improvement due to its disease resistance, large spikes, large leaves, and multiple flowers. In this study, a recombinant inbred line (RIL) population was derived from common wheat Yannong15 and wheat-Th. intermedium introgression line SN304 was used to identify the quantitative trait loci (QTL) for flag leaf-related traits. RESULTS: QTL mapping was performed for flag leaf length (FLL), flag leaf width (FLW) and flag leaf area (FLA). A total of 77 QTLs were detected, and among these, 51 QTLs with positive alleles were contributed by SN304. Fourteen major QTLs for flag leaf traits were detected on chromosomes 2B, 3B, 4B, and 2D. Additionally, 28 QTLs and 8 QTLs for flag leaf-related traits were detected in low-phosphorus and drought environments, respectively. Based on major QTLs of positive alleles from SN304, we identified a pair of double-ended anchor primers mapped on chromosome 2B and amplified a specific band of Th. intermedium in SN304. Moreover, there was a major colocated QTL on chromosome 2B, called QFll/Flw/Fla-2B, which was delimited to a physical interval of approximately 2.9 Mb and contained 20 candidate genes. Through gene sequence and expression analysis, four candidate genes associated with flag leaf formation and growth in the QTL interval were identified. CONCLUSION: These results promote the fine mapping of QFll/Flw/Fla-2B, which have pleiotropic effects, and will facilitate the identification of candidate genes for flag leaf-related traits. Additionally, this work provides a theoretical basis for the application of Th. intermedium in wheat breeding.

Characterization of a wheat stable QTL for spike length and its genetic effects on yield-related traits.

Spike length (SL) is one of the most important agronomic traits affecting yield potential and stability in wheat. In this study, a major stable quantitative trait locus (QTL) for SL, i.e., qSl-2B, was detected in multiple environments in a recombinant inbred line (RIL) mapping population, KJ-RILs, derived from a cross between Kenong 9204 (KN9204) and Jing 411 (J411). The qSl-2B QTL was mapped to the 60.06-73.06 Mb region on chromosome 2B and could be identified in multiple mapping populations. An InDel molecular marker in the target region was developed based on a sequence analysis of the two parents. To further clarify the breeding use potential of qSl-2B, we analyzed its genetic effects and breeding selection effect using both the KJ-RIL population and a natural mapping population, which consisted of 316 breeding varieties/advanced lines. The results showed that the qSl-2B alleles from KN9204 showed inconsistent genetic effects on SL in the two mapping populations. Moreover, in the KJ-RILs population, the additive effects analysis of qSl-2B showed that additive effect was higher when both qSl-2D and qSl-5A harbor negative alleles under LN and HN. In China, a moderate selection utilization rate for qSl-2B was found in the Huanghuai winter wheat area and the selective utilization rate for qSl-2B continues to increase. The above findings provided a foundation for the genetic improvement of wheat SL in the future via molecular breeding strategies.

Foliar application of plant-derived peptides decreases the severity of leaf rust (Puccinia triticina) infection in bread wheat (Triticum aestivum L.).

BACKGROUND: Screening and developing novel antifungal agents with minimal environmental impact are needed to maintain and increase crop production, which is constantly threatened by various pathogens. Small peptides with antimicrobial and antifungal activities have been known to play an important role in plant defense both at the pathogen level by suppressing its growth and proliferation as well as at the host level through activation or priming of the plant's immune system for a faster, more robust response against fungi. Rust fungi (Pucciniales) are plant pathogens that can infect key crops and overcome resistance genes introduced in elite wheat cultivars. RESULTS: We performed an in vitro screening of 18 peptides predominantly of plant origin with antifungal or antimicrobial activity for their ability to inhibit leaf rust (Puccinia triticina, CCDS-96-14-1 isolate) urediniospore germination. Nine peptides demonstrated significant fungicidal properties compared to the control. Foliar application of the top three candidates, ß-purothionin, Purothionin-α2 and Defensin-2, decreased the severity of leaf rust infection in wheat (Triticum aestivum L.) seedlings. Additionally, increased pathogen resistance was paralleled by elevated expression of defense-related genes. CONCLUSIONS: Identified antifungal peptides could potentially be engineered in the wheat genome to provide an alternative source of genetic resistance to leaf rust.

pH change accompanying long-distance electrical signal controls systemic jasmonate biosynthesis.

Local damaging stimuli cause a rapid increase in the content of the defense phytohormone jasmonic acid (JA) and its biologically active derivative jasmonoyl-L-isoleucine (JA-Ile) in undamaged distal tissues. The increase in JA and JA-Ile levels was coincident with a rapid decrease in the levels of the precursor 12-oxo-phytodienoic acid (OPDA). The propagation of a stimulus-induced long-distance electrical signal, variation potential (VP), which is accompanied by intracellular changes in pH and Ca2+ levels, preceded systemic changes in jasmonate content. The decrease in pH during VP, mediated by transient inactivation of the plasma membrane H+-ATPase, induced the conversion of OPDA to JA, probably by regulating the availability of the OPDA substrate to JA biosynthetic enzymes. The regulation of systemic synthesis of JA and JA-Ile by the Ca2+ wave accompanying VP most likely occurs by the same mechanism of pH-induced conversion of OPDA to JA due to Ca2+-mediated decrease in pH as a result of H+-ATPase inactivation. Thus, the transient increase in intracellular Ca2+ levels and the transient decrease in intracellular pH are most likely the key mechanisms of VP-mediated regulation of jasmonate production in systemic tissues upon local stimulation.