Breeding semi-dwarf cultivars has long been a major objective for wheat improvement due to the inseparable association between plant height (PH) and grain yield. Although the utilization of Rht-B1b and Rht-D1b genes successfully achieved semi-dwarfism in the 1960s, these genes were associated with undesirable traits. The current wheat breeding urgently requires continuously exploring PH-controlling genes and their regulatory mechanisms, which will expand the genetic diversity of the PH gene pool to achieve precise PH regulation while maintaining or even increasing the grain yield potential. In this study, we identified a gibberellin (GA)-sensitive dwarf mutant, designated wph3 (wheat plant height 3). It showed GA biosynthesis deficiency and had pleiotropic effects on PH, spike length, grain weight, and grain number per spike. Using Exome Capture Sequencing for Bulked Segregant Analysis and molecular marker mapping, a novel recessive nuclear dwarfing gene was identified and localized into a 3.9 Mb physical interval on chromosome 2B, designated Rht29 (Reduced height 29). Transcriptome analysis and candidate gene mining indicated that Rht29 may not encode a canonical key enzyme for GA biosynthesis, but participate in the GA biosynthesis by regulating the expression level of GA3ox. This study enriches the genetic resources available for wheat dwarfing breeding and establishes a foundation for further molecular characterization of phenotypic regulation by Rht29.

Leaf senescence is a turning point for grain development and closely related to yield and grain quality. Fine-tuning leaf senescence could be a vital strategy for yield improvement. However, our knowledge of the regulatory genes of leaf senescence is limited in wheat. In this study, we identified a methanesulfonate (EMS) mutant, wheat pale green 1 (wpg1), exhibiting obvious leaf chlorisis and premature senescence (PS) since the jointing stage. The chloroplast structure of the chlorisis leaf of wpg1 seemed intact, whereas its chlorophyll content was significantly decreased compared to the wild type (WT). The content of nitrogen (N), the core element for chlorophyll, was much lower in leaves of wpg1 than in WT. The spatio-temporal pattern analysis of nitrogen content further indicated accelerated N allocation from vegetation tissues to spike in wpg1, resulting in a significant decrease in nitrogen content in leaves, but a substantial increase in grains compared to WT. Genetic analysis showed that leaf chlorisis and PS is controlled by a single dominant locus, designated as Wheat Pale Green 1 (WPG1), which was further mapped to a physical interval of 34.69 M-41.19 M on chromosome 2A. Transcriptomic analysis revealed that expression of photosynthesis-related genes, and N absorption and transportation genes consistently decreased in wpg1, which revalidated the underlying relationship between N shortage and leaf chlorisis. The results presented here lays the basis for further dissecting the causal gene of WPG1 and the subsequent molecular mechanism underlying the regulation of leaf senescence, N allocation, and possibly the photosynthesis in wheat.

BACKGROUND:Plant height (PH), as a key trait of plant architecture, is the embodiment of biomass accumulation and plays a critical role in determining wheat yield. Excavating diverse PH genes and understanding their pleiotropic effects on important agronomic traits are essential to enrich the PH gene pool and facilitate their further application in breeding. RESULTS:In this study, five stable PH QTLs were identified on chromosome 2B, 4A, 4B, 5A and 6A in a double haploid (DH) population from the cross between two elite wheat cultivars, Chuanmai 42 and Kechengmai 1. The QPh.cib-4B and QPh.cib-6A were major QTL and had a significant additive effect on PH. The QPh.cib-4B was confirmed as the Rht-B1, and QPh.cib-6A might be a new QTL. The major QTLs were further validated in different genetic backgrounds using the Kompetitive Allele-Specific PCR (KASP) markers. Using near-isogenic lines (NILs), QPh.cib-6A was demonstrated to pleiotropically increase plant height (PH), thousand grain weight (TGW), and spike length (SL) without negatively affecting grain number per spike (GNS) or spikelet number per spike (SNS). In contrast, QPh.cib-4B exhibited significant effects on PH but had no influence on TGW, GNS, SL, or SNS. Notably, the frequency of elite haplotype of QPh.cib-6A remains relatively low in Chinese wheat varieties. Thus, the combination of QPh.cib-4B and QPh.cib-6A represents a promising genetic module with considerable potential for high-yield wheat breeding. Expression analysis in NILs and sequence characterization identified TraesCS6A02G234400 and TraesCS6A02G235300 as the candidate genes for QPh.cib-6A. CONCLUSIONS:This study identified five QTLs for PH in wheat. Two major QTLs were further validated in different genetic backgrounds, and their genetic effects on yield-related traits were analyzed in near-isogenic lines (NILs) to evaluate their potential in wheat breeding. Taken together, our results advance our understanding of the genetic basis for PH and enrich the PH QTL pool. CLINICAL TRIAL NUMBER:Not applicable.

Seven stable QTLs for TGW, GW and GL were identified, and two major QTLs were stable in various genetic backgrounds and environments. Thousand grain weight (TGW), mainly determined by grain length (GL) and width (GW), is an important yield component of wheat. In the study, combined with phenotyping in four field trials and a high-quality genetic map constructed with the wheat 55 K SNP array, a total of seven stable QTLs for TGW, GW and GL were identified in a doubled haploid (DH) population derived from the cross between Chuanmai 42 (CM42) and Kechengmai 4 (K4), in which QTgw.CK4-cib-3D, QGw.CK4-cib-2D and QGl.CK4-cib-5 A.1 were novel, and QTgw/Gw.CK4-cib-6 A and QGl.CK4-cib-5 A.1 were major QTLs explaining more than 10

Tryptophan decarboxylase (TDC), the rate-limiting enzyme of tryptophan metabolism in plants, is essential for the production of a series of bioactive molecules, such as serotonin, melatonin and the plant hormone indole-3-acetic acid and therefore plays crucial roles in various aspects of growth and development. However, its roles in determining wheat grain quality and stress resilience capacity remain unknown, limiting its utilisation in wheat improvement. In this study, we found that overexpression of AevTDC1 (AevTDC1-OX) of Aegilops variabilis, a wheat relative, did not significantly impair yield-related traits of wheat, but remarkably elevated the content of tryptamine, serotonin, melatonin and gamma-aminobutyric acid in the grains. Additionally, AevTDC1-OX simultaneously improved the defensive capabilities to cereal cyst nematode (CCN) and drought stress. Besides the known role in responding to CCN infection by regulating salicylic acid biosynthesis, we further found that AevTDC1-OX increased the expression of TaXTH23 and consequently enhanced cell wall thickness in the root. On the other hand, we observed significantly promoted ethylene biosynthesis in AevTDC1-OX wheat, which contributed to improved drought tolerance by controlling stomatal aperture. Moreover, TaWRKY65, upregulated by both AevTDC1-OX and drought stress, was unveiled to positively regulate drought tolerance. We proved that this function was achieved, at least partly, through directly modulating ethylene biosynthesis via promoting the expression of TaACS, a key ethylene biosynthesis gene. These results provide new knowledge on the essential roles of TDC in the functional quality of grains and the stress resilience capacity in wheat, revealing great potential for the manipulation of tryptophan metabolism for application in wheat genetic improvement.

A major locus for spike compactness and length was mapped on chromosome 7H and its pleiotropic effects, candidate genes and transcriptional regulatory network were analyzed. Spike compactness (SC) and length (SL) are important traits of barley (Hordeum vulgare L.) due to their close association with grain yield. In this study, a major SC and SL locus QSc/Sl.cib-7H was primarily identified on chromosome 7H by bulked segregant analysis, and further fine mapped to a recombination cold spot expanding 244.36–388.09 Mb by developing a secondary population using residual heterozygous lines. This region is much more accurate than previously reported spike compactness loci on chromosome 7H. The strong effects of QSc/Sl.cib-7H on SL and SC were validated in two pair of near isogenic lines (NILs) and diverse genetic backgrounds. QSc/Sl.cib-7H exhibited pleiotropic effects on plant height (PH), thousand grain weight and grain length, and did not significantly influence the spikelet number of main spike (SMS) and grain width. Transcriptome analysis based on NILs showed that regulation of SC and SL might be related to the plant circadian rhythm pathway. The candidate genes were mined by analyzing variants and expression patterns of genes in the target region employing multiple genome and transcriptome data. This study takes a further step towards cloning of QSc/Sl.cib-7H, and the data obtained and the developed molecular markers will facilitate its utilization in barley breeding.

Spike-related traits and plant height (PH) are greatly associated with wheat yield. Identification of stable quantitative trait loci (QTL) for these traits is crucial for understanding the genetic basis for yield and their further application in breeding. In this study, QTL analysis for spikelet number per spike (SNS), spike length (SL), spike compactness (SC) and PH was performed using a recombinant inbred line (RIL) population derived from a cross between wheat cultivars Mianmai902 (MM902) and Taichang29 (TC29). Thirteen stably expressed QTLs were identified, and the most favorable alleles were contributed by MM902. The mjaor QTL, QSNS-MT.cib-2D, QSL-MT.cib-2D, QSC-MT.cib-2D, QSC-MT.cib-6 A, QPH-MT.cib-4B and QPH-MT.cib-4D, were repeatedly detected in multiple environments and explained 5.77-47.11

Background Yield-related traits including thousand grain weight (TGW), grain number per spike (GNS), grain width (GW), grain length (GL), plant height (PH), spike length (SL), and spikelet number per spike (SNS) are greatly associated with grain yield of wheat ( Triticum aestivum L.). To detect quantitative trait loci (QTL) associated with them, 193 recombinant inbred lines derived from two elite winter wheat varieties Chuanmai42 and Chuanmai39 were employed to perform QTL mapping in six/eight environments. Results A total of 30 QTLs on chromosomes 1A, 1B, 1D, 2A, 2B, 2D, 3A, 4A, 5A, 5B, 6A, 6D, 7A, 7B and 7D were identified. Among them, six major QTLs QTgw.cib-6A.1 , QTgw.cib-6A.2 , QGw.cib-6A , QGl.cib-3A , QGl.cib-6A , and QSl.cib-2D explaining 5.96-23.75% of the phenotypic variance were detected in multi-environments and showed strong and stable effects on corresponding traits. Three QTL clusters on chromosomes 2D and 6A containing 10 QTLs were also detected, which showed significant pleiotropic effects on multiple traits. Additionally, three Kompetitive Allele Specific PCR (KASP) markers linked with five of these major QTLs were developed. Candidate genes of QTgw.cib-6A.1/QGl.cib-6A and QGl.cib-3A were analyzed based on the spatiotemporal expression patterns, gene annotation, and orthologous search. Conclusions Six major QTLs for TGW, GL, GW and SL were detected. Three KASP markers linked with five of these major QTLs were developed. These QTLs and KASP markers will be useful for elucidating the genetic architecture of grain yield and developing new wheat varieties with high and stable yield in wheat.

Protein phosphatase 2Cs (PP2Cs) are negative regulators in the classic abscisic acid (ABA)-mediated drought stress signaling network. However, some members of PP2Cs can regulate the resistant to abiotic stresses positively, which provided a new way to solve the problem of low yield under severe environment. PP2C genes have been studied in many plants, but not been reported in Tibetan hulless barley, which survived from harsh environment and can be used as a good subject for analyzing drought tolerance mechanism. Fifty-four PP2C genes were identified in hulless barley under dehydration stress from our previous RNA-Seq data. Of these PP2Cs, 12 were significantly induced under dehydration stress and may be considered drought resistance candidate genes. Phylogenetic study showed that these HvPP2Cs can be classified into 12 major clusters (group A-I, K-M). HvPP2C59, which belongs to group F, showed remarkable continuously upregulated pattern during dehydration stress, was cloned in this study. Bioinformatics analysis identified motifs such as ABRE, MeJA, and G-box (light responsiveness) within its promoter region. Expression analysis indicated that HvPP2C59 can be promoted under drought, NaCl, and polyethylene glycol (PEG) 6000 stress, suppressed under dark, but was almost unaffected with ABA treatment. HvPP2C59-silenced plants had higher leaf water loss rate (WLR) and lower survival rate (SR) compared with controls under dehydration stress. The silenced plants also showed retarded vegetative growth under normal condition. Silencing of HvPP2C59 resulted in restrained expression of cold-regulated gene, LEA genes, and JA bio-synthesis key gene AOC. The study of PP2C genes in hulless barley will provide practical support to further expound the specific mechanism of plant response to drought stress.

Morphological, genetic and transcriptomic characterizations of an EMS-induced wheat paired spikelets (PS) mutant were performed. A novel qualitative locus WPS1 on chromosome 1D was identified. Grain yield of wheat is significantly associated with inflorescence or spike architecture. However, few genes related to wheat spike development have been identified and their underlying mechanisms are largely unknown. In this study, we characterized an ethyl methanesulfonate (EMS)-induced wheat mutant, wheat paired spikelets 1 (wps1). Unlike a single spikelet that usually develops at each node of rachis, a secondary spikelet appeared below the primary spikelet at most of the rachis nodes of wps1. The microscope observation showed that the secondary spikelet initiated later than the primary spikelet. Genetic analysis suggested that the PS of wps1 is controlled by a single dominant nuclear gene, designated WHEAT PAIRED SPIKELETS 1 (WPS1). Further RNA-seq based bulked segregant analysis and molecular marker mapping localized WPS1 in an interval of 208.18–220.92 Mb on the chromosome arm 1DL, which is different to known genes related to spike development in wheat. By using wheat omics data, TraesCS1D02G155200 encoding a HD-ZIP III transcription factor was considered as a strong candidate gene for WPS1. Transcriptomic analysis indicated that PS formation in wps1 is associated with auxin-related pathways and may be regulated by networks involving TB1, Ppd1, FT1, VRN1, etc. This study laid the solid foundation for further validation of the causal gene of WPS1 and explored its regulatory mechanism in PS formation and inflorescence development, which may benefit to kernel yield improvement of wheat based on optimization or design of spike architecture in the future.

Decisive role of reduced vrs1 transcript abundance in six-rowed spike of barley carrying vrs1.a4 was genetically proved and its potential causes were preliminarily analyzed. Six-rowed spike 1 (vrs1) is the major determinant of the six-rowed spike phenotype of barley (Hordeum vulgare L.). Alleles of Vrs1 have been extensively investigated. Allele vrs1.a4 in six-rowed barley is unique in that it has the same coding sequence as Vrs1.b4 in two-rowed barley. The determinant of row-type in vrs1.a4 carriers has not been experimentally identified. Here, we identified Vrs1.b4 in two-rowed accessions and vrs1.a4 in six-rowed accessions from the Qinghai–Tibet Plateau at high frequency. Genetic analyses revealed a single nuclear gene accounting for row-type alteration in these accessions. Physical mapping identified a 0.08-cM (~ 554-kb) target interval on chromosome 2H, wherein Vrs1 was the most likely candidate gene. Further analysis of Vrs1 expression in offspring of the mapping populations or different Vrs1.b4 and vrs1.a4 lines confirmed that downregulated expression of vrs1.a4 causes six-rowed spike. Regulatory sequence analysis found a single ‘TA’ dinucleotide deletion in vrs1.a4 carriers within a ‘TA’ tandem-repeat–enriched region ~ 1 kb upstream of the coding region. DNA methylation levels did not correspond to the expression difference and therefore did not affect Vrs1 expression. More evidence is needed to verify the causal link between the ‘TA’ deletion and the downregulated Vrs1 expression and hence the six-rowed spike phenotype.

BACKGROUND:Tibetan hulless barley (Hordeum vulgare var. nudum), adjusting to the harsh environment on Qinghai-Tibet Plateau, is a good subject for analyzing drought tolerance mechanism. Several unannotated differentially expressed genes (DEGs) were identified through our previous RNA-Seq study using two hulless barley accessions with contrasting drought tolerance. One of these DEGs, HVU010048.2, showed up-regulated pattern under dehydration stress in both drought tolerant (DT) and drought susceptible (DS) accessions, while its function in drought resistance remains unknown. This new gene was named as HvLRX (light responsive X), because its expression was induced under high light intensity while suppressed under dark.OBJECTIVE:To provide preliminary bioinformatics prediction, expression pattern, and drought resistance function of this new gene.METHODS:Bioinformatics analysis of HvLRX were conducted by MEGA, PlantCARE, ProtParam, CELLO et al. The expression pattern of HvLRX under different light intensity, dehydration shock, gradual drought stress, NaCl stress, polyethylene glycol (PEG) 6000 stress and abscisic acid (ABA) treatment was investigated by quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The function of HvLRX was analyzed by virus induced gene silencing (VIGS) in hulless barley and by transgenic method in tobacco.RESULTS:Full cDNAs of HvLRX were cloned and compared in three hulless barley accessions. Homologues of HvLRX protein in other plants were excavated and their phylogenetic relationship was analyzed. Several light responsive elements (ATC-motif, Box 4, G-box, Sp1, and chs-CMA1a) were identified in its promoter region. Its expression can be promoted under high light intensity, dehydration shock, gradual drought stress, PEG 6000, and NaCl stress, but was almost unchanged in ABA treatment. HvLRX-silenced plants had a higher leaf water loss rate (WLR) and a lower survival rate (SR) compared with controls under dehydration stress. The infected leaves of HvLRX-silenced plants lost their water content quickly and became withered at 10 dpi. The SR of HvLRX overexpressed transgenic tobacco plants was significantly higher than that of wild-type plants. These results indicated HvLRX play a role in drought resistance. Besides, retarded vegetative growth was detected in HvLRX-silenced hulless barley plants, which suggested that this gene is important for plant development.CONCLUSIONS:This study provided data of bioinformatics, expression pattern, and function of HvLRX. To our knowledge, this is the first report of this new dehydration and light responsive gene.

A novel qualitative locus regulating the uppermost internode elongation of barley was identified and mapped on 6H, and the candidate gene mining was performed by employing various barley genomic resources. The stem of grass crops, such as barley and wheat, is composed of several interconnected internodes. The extent of elongation of these internodes determines stem height, and hence lodging, canopy architecture, and grain yield. The uppermost internode (UI) is the last internode to elongate. Its elongation contributes largely to stem height and facilitates spike exsertion, which is crucial for final grain yield. Despite the molecular mechanism underlying regulation of UI elongation was extensively investigated in rice, little is known in barley. In this study, we characterized a barley spontaneous mutant, Sheathed Spike 1 (SS1), showing significantly shortened UI and sheathed spike (SS). The extension of UI parenchyma cell in SS1 was significantly suppressed. Exogenous hormone treatments and RNA-seq analysis indicated that the suppression of UI elongation is possibly related to insufficient content of endogenous bioactive gibberellin. Genetic analysis showed that SS1 is possibly controlled by a qualitative dominant nuclear factor. Bulked segregant analysis and further molecular marker mapping identified a novel major locus, HvSS1, in a recombination cold spot expanding 173.44–396.33 Mb on chromosome 6H. The candidate gene mining was further conducted by analyzing sequence differences, spatiotemporal expression patterns, and variant distributions of genes in the candidate interval by employing various barley genomic resources of worldwide collections of barley accessions. This study made insight into genetic control of UI elongation in barley and laid a solid foundation for further gene cloning and functional characterization. The results obtained here also provided valuable information for similar research in wheat.

Spikelet number is an important target trait for wheat yield improvement. Thus, the identification and verification of novel quantitative trait locus (QTL)/genes controlling spikelet number are essential for dissecting the underlying molecular mechanisms and hence for improving grain yield. In the present study, we constructed a high-density genetic map for the Kechengmai1/Chuanmai42 doubled haploid (DH) population using 13,068 single-nucleotide polymorphism (SNP) markers from the Wheat 55K SNP array. A comparison between the genetic and physical maps indicated high consistence of the marker orders. Based on this genetic map, a total of 27 QTLs associated with total spikelet number per spike (TSN) and fertile spikelet number per spike (FSN) were detected on chromosomes 1B, 1D, 2B, 2D, 3D, 4A, 4D, 5A, 5B, 5D, 6A, 6B, and 7D in five environments. Among them, five QTLs on chromosome 2D, 3D, 5A, and 7D were detected in multiple environments and combined QTL analysis, explaining the phenotypic variance ranging from 3.64% to 23.28%. Particularly, QTsn/Fsn.cib-3D for TSN and FSN [phenotypic variation explained (PVE) = 5.97–23.28%, limit of detection (LOD) = 3.73–18.51] is probably a novel locus and located in a 4.5-cM interval on chromosome arm 3DL flanking by the markers AX-110914105 and AX-109429351. This QTL was further validated in other two populations with different genetic backgrounds using the closely linked Kompetitive Allele-Specific PCR (KASP) marker KASP_AX-110914105. The results indicated that QTsn/Fsn.cib-3D significantly increased the TSN (5.56–7.96%) and FSN (5.13–9.35%), which were significantly correlated with grain number per spike (GNS). We also preliminary analyzed the candidate genes within this locus by sequence similarity, spatial expression patterns, and collinearity analysis. These results provide solid foundation for future fine mapping and cloning of QTsn/Fsn.cib-3D. The developed and validated KASP markers could be utilized in molecular breeding aiming to increase the grain yield in wheat.

Key message Two major and stable QTLs for spike compactness and length were detected and validated in multiple genetic backgrounds and environments, and their pleiotropic effects on yield-related traits were analyzed. Spike compactness (SC) and length (SL) are greatly associated with wheat (Triticum aestivum L.) grain yield. To detect quantitative trait loci (QTL) associated with SC and SL, two biparental populations derived from crosses of Chuanmai42/Kechengmai1 and Chuanmai42/Chuannong16 were employed to perform QTL mapping in five environments. A total of 34 QTLs were identified, in which six major QTLs were repeatedly detected in more than four environments and the best linear unbiased prediction datasets, explaining 7.13-33.6% of phenotypic variation. These major QTLs were co-located in two genomic regions on chromosome 5A and 6A, namely QSc/Sl.cib-5A and QSc/Sl.cib-6A, respectively. By developing kompetitive allele-specific PCR (KASP) markers that linked to them, the two loci were validated in different genetic backgrounds, and their interactions were also analyzed. Comparison analysis showed that QSc/Sl.cib-5A was not Vrn-A1 and Q, and QSc/Sl.cib-6A was likely a new locus for SC and SL. Both QSc/Sl.cib-5A and QSc/Sl.cib-6A had pleiotropic effects on other yield-related traits including plant height, thousand grain weight and grain length. Therefore, the two loci combined with the developed KASP markers might be potentially applicable in wheat breeding. Furthermore, based on the spatiotemporal expression patterns, gene annotation, orthologous search and sequence differences, TraesCS5A01G301400 and TraesCS6A01G090300 were considered as potential candidates for QSc/Sl.cib-5A and QSc/Sl.cib-6A, respectively. These results provided valuable information for fine mapping and cloning of the two loci in the future.

KEY MESSAGE:Six major QTLs for wheat grain size and weight were identified on chromosomes 4A, 4B, 5A and 6A across multiple environments, and were validated in different genetic backgrounds. Grain size and weight are crucial components of wheat yield. Dissection of their genetic control is thus essential for the improvement of yield potential in wheat breeding. We used a doubled haploid (DH) population to detect quantitative trait loci (QTLs) for grain width (GW), grain length (GL), and thousand grain weight (TGW) in five environments. Six major QTLs, QGw.cib-4B.2, QGl.cib-4A, QGl.cib-5A.1, QGl.cib-6A, QTgw.cib-4B, and QTgw.cib-5A, were consistently identified in at least three individual environments and in best linear unbiased prediction (BLUP) datasets, and explained 5.65-34.06% of phenotypic variation. QGw.cib-4B.2, QTgw.cib-4B, QGl.cib-5A.1 and QGl.cib-6A had no effect on grain number per spike (GNS). In addition to QGl.cib-4A, the other major QTLs were further validated by using Kompetitive Allele Specific PCR (KASP) markers in different genetic backgrounds. Moreover, significant interactions between the three major GL QTLs and two major TGW QTLs were observed. Comparison analysis showed that QGl.cib-5A.1 and QGl.cib-6A are likely new loci. Notably, QGw.cib-4B.2 and QTgw.cib-4B were co-located on chromosome 4B and improved TGW by increasing only GW, unlike nearby or overlapped loci reported previously. Three genes associated with grain development within the QGw.cib-4B.2/QTgw.cib-4B interval were identified by searches on sequence similarity, spatial expression patterns, and orthologs. The major QTLs and KASP markers reported here will be useful for elucidating the genetic architecture of grain size and weight and for developing new wheat cultivars with high and stable yield.

The pathogen cereal cyst nematode (CCN) is deleterious to Triticeae crops and is a threat to the global crop yield. Accession no. 1 of Aegilops variabilis, a relative of Triticum aestivum (bread wheat), is highly resistant to CCN. Our previous study demonstrated that the expression of the phenylalanine ammonia lyase (PAL) gene AevPAL1 in Ae. variabilis is strongly induced by CCN. PAL, the first enzyme of phenylpropanoid metabolism, is involved in abiotic and biotic stress responses. However, its role in plant-CCN interaction remains unknown. In the present study, we proved that AevPAL1 helps to confer CCN resistance through affecting the synthesis of salicylic acid (SA) and downstream secondary metabolites. The silencing of AevPAL1 increased the incidence of CCN infection in roots and decreased the accumulation of SA and phenylalanine (Phe)-derived specialized metabolites. The exogenous pre-application of SA also improved CCN resistance. Additionally, the functions of PAL in phenylpropanoid metabolism correlated with tryptophan decarboxylase (TDC) functioning in tryptophan metabolism pathways. The silencing of either AevPAL1 or AevTDC1 exhibited a concomitant reduction in the expression of both genes and the contents of metabolites downstream of PAL and TDC. These results suggested that AevPAL1, possibly in coordination with AevTDC1, positively contributes to CCN resistance by altering the downstream secondary metabolites and SA content in Ae. variabilis. Moreover, AevPAL1 overexpression significantly enhanced CCN resistance in bread wheat and did not exhibit significant negative effects on yield-related traits, suggesting that AevPAL1 is valuable for the genetic improvement of CCN resistance in bread wheat.

[目的]对两份穗伸出差异显著的大麦(Hordeum vulgare L.)材料的最上节间(UI)进行全长转录组分析,为揭示大麦UI伸长调控机制奠定基础.[方法]以包穗大麦材料CDB0012和穗伸出正常大麦品种XL19为材料,利用Nanopore平台开展了UI全长转录组测序和生物信息分析.[结果]共获得46246条非冗余全长转录本,鉴定了2395个潜在新基因位点和44805条新转录本,开展了功能注释、可变剪切、差异表达基因鉴定等分析.[结论]构建了一套高质量大麦UI全长转录组数据集.

Numerous quantitative trait loci (QTLs) have been identified for wheat quality; however, most are confined to low-density genetic maps. In this study, based on specific-locus amplified fragment sequencing (SLAF-seq), a high-density genetic map was constructed with 193 recombinant inbred lines derived from Chuanmai 42 and Chuanmai 39. In total, 30 QTLs with phenotypic variance explained (PVE) up to 47.99% were identified for falling number (FN), grain protein content (GPC), grain hardness (GH), and starch pasting properties across three environments. Five NAM genes closely adjacent to QGPC.cib-4A probably have effects on GPC. QGH.cib-5D was the only one detected for GH with high PVE of 33.31–47.99% across the three environments and was assumed to be related to the nearest pina-D1 and pinb-D1genes. Three QTLs were identified for FN in at least two environments, of which QFN.cib-3D had relatively higher PVE of 16.58–25.74%. The positive effect of QFN.cib-3D for high FN was verified in a double-haploid population derived from Chuanmai 42 × Kechengmai 4. The combination of these QTLs has a considerable effect on increasing FN. The transcript levels of Basic 7S globulin and Basic 7S globulin 2 in QFN.cib-3D were significantly different between low FN and high FN bulks, as observed through bulk segregant RNA-seq (BSR). These QTLs and candidate genes based on the high-density genetic map would be beneficial for further understanding of the genetic mechanism of quality traits and molecular breeding of wheat.

[This corrects the article DOI: 10.3389/fpls.2018.01297.].