The auxin response factor TaARF15-A1 negatively regulates senescence in common wheat (Triticum aestivum L.).

Auxin plays an important role in regulating leaf senescence. Auxin response factors (ARFs) are crucial components of the auxin signaling pathway; however, their roles in leaf senescence in cereal crops are unknown. In this study, we identified TaARF15-A1 as a negative regulator of senescence in wheat (Triticum aestivum L.) by analyzing TaARF15-A1 overexpression (OE) and RNA interference lines and CRISPR/Cas9-based arf15 mutants. OE of TaARF15-A1 delayed senescence, whereas knockdown lines and knockout mutants showed accelerated leaf senescence and grain ripening. RNA-seq analysis revealed that TaARF15-A1 delays leaf senescence by negatively regulating senescence-promoting processes and positively modulating senescence-delaying genes including senescence-associated phytohormone biosynthesis and metabolism genes as well as transcription factors (TFs). We also demonstrated that TaARF15-A1 physically interacts with TaMYC2, a core jasmonic acid (JA) signaling TF that positively modulates wheat senescence. Furthermore, TaARF15-A1 suppressed the expression of TaNAM-1 (TaNAM-A1 and TaNAM-D1) via protein-protein interaction and competition with TaMYC2 for binding to its promoter to regulate senescence. Finally, we identified two haplotypes of TaARF15-A1 in global wheat collections. Association analysis revealed that TaARF15-A1-HapI has undergone strong selection during wheat breeding in China, likely owing to its earlier maturity. Thus, we identify TaARF15-A1 as a negative regulator of senescence in common wheat and present another perspective on the crosstalk between auxin and JA signaling pathways in regulating plant senescence.

Molecular characterization of QTL for grain zinc and iron concentrations in wheat landrace Chinese Spring.

KEY MESSAGE: Three stable QTL for grain zinc concentration were identified in wheat landrace Chinese Spring. Favorable alleles were more frequent in landraces than in modern wheat cultivars. Wheat is a major source of dietary energy for the growing world population. Developing cultivars with enriched zinc and iron can potentially alleviate human micronutrient deficiency. In this study, a recombinant inbred line (RIL) population with 245 lines derived from cross Zhou 8425B/Chinese Spring was used to detect quantitative trait loci (QTL) for grain zinc concentration (GZnC) and grain iron concentration (GFeC) across four environments. Three stable QTL for GZnC with all favorable alleles from Chinese Spring were identified on chromosomes 3BL, 5AL, and 5BL. These QTL explaining maxima of 8.7%, 5.8%, and 7.1% of phenotypic variances were validated in 125 resequenced wheat accessions encompassing both landraces and modern cultivars using six kompetitive allele specific PCR (KASP) assays. The frequencies of favorable alleles for QGZnCzc.caas-3BL, QGZnCzc.caas-5AL and QGZnCzc.caas-5BL were higher in landraces (90.4%, 68.0%, and 100.0%, respectively) compared to modern cultivars (45.9%, 35.4%, and 40.9%), suggesting they were not selected in breeding programs. Candidate gene association studies on GZnC in the cultivar panel further delimited the QTL into 8.5 Mb, 4.1 Mb, and 47.8 Mb regions containing 46, 4, and 199 candidate genes, respectively. The 5BL QTL located in a region where recombination was suppressed. Two stable and three less stable QTL for GFeC with favorable alleles also from Chinese Spring were identified on chromosomes 4BS (Rht-B1a), 4DS (Rht-D1a), 1DS, 3AS, and 6DS. This study sheds light on the genetic basis of GZnC and GFeC in Chinese Spring and provides useful molecular markers for wheat biofortification.

The TaGW2-TaSPL14 module regulates the trade-off between tiller number and grain weight in wheat.

IDEAL PLANT ARCHITECTURE1 (IPA1) is a pivotal gene controlling plant architecture and grain yield. However, little is known about the effects of Triticum aestivum SQUAMOSA PROMOTER-BINDING-LIKE 14 (TaSPL14), an IPA1 ortholog in wheat, on balancing yield traits and its regulatory mechanism in wheat (T. aestivum L.). Here, we determined that the T. aestivum GRAIN WIDTH2 (TaGW2)-TaSPL14 module influences the balance between tiller number and grain weight in wheat. Overexpression of TaSPL14 resulted in a reduced tiller number and increased grain weight, whereas its knockout had the opposite effect, indicating that TaSPL14 negatively regulates tillering while positively regulating grain weight. We further identified TaGW2 as a novel interacting protein of TaSPL14 and confirmed its ability to mediate the ubiquitination and degradation of TaSPL14. Based on our genetic evidence, TaGW2 acts as a positive regulator of tiller number, in addition to its known role as a negative regulator of grain weight, which is opposite to TaSPL14. Moreover, combinations of TaSPL14-7A and TaGW2-6A haplotypes exhibit significantly additive effects on tiller number and grain weight in wheat breeding. Our findings provide insight into how the TaGW2-TaSPL14 module regulates the trade-off between tiller number and grain weight and its potential application in improving wheat yield.

Conservatively transmitted alleles of key agronomic genes provide insights into the genetic basis of founder parents in bread wheat (Triticum aestivum L.).

BACKGROUND: Founder parents play extremely important roles in wheat breeding. Studies into the genetic basis of founder parents and the transmission rules of favorable alleles are of great significance in improving agronomically important traits in wheat. RESULTS: Here, a total of 366 founder parents, widely grown cultivars, and derivatives of four representative founder parents were genotyped based on efficient kompetitive allele-specific PCR (KASP) markers in 87 agronomically important genes controlling yield, quality, adaptability, and stress resistance. Genetic composition analysis of founder parents and widely grown cultivars showed a consistently high frequency of favorable alleles for yield-related genes. This analysis further showed that other alleles favorable for resistance, strong gluten, dwarf size, and early heading date were also subject to selective pressure over time. By comparing the transmission of alleles from four representative founder parents to their derivatives during different breeding periods, it was found that the genetic composition of the representative founder parents was optimized as breeding progressed over time, with the number and types of favorable alleles carried gradually increasing and becoming enriched. There are still a large number of favorable alleles in wheat founder parents that have not been fully utilized in breeding selection. Eighty-seven agronomically important genes were used to construct an enrichment map that shows favorable alleles of four founder parents, providing an important theoretical foundation for future identification of candidate wheat founder parents. CONCLUSIONS: These results reveal the genetic basis of founder parents and allele transmission for 87 agronomically important genes and shed light on breeding strategies for the next generation of elite founder parents in wheat.

TaTPP-7A positively feedback regulates grain filling and wheat grain yield through T6P-SnRK1 signalling pathway and sugar-ABA interaction.

Grain size and filling are two key determinants of grain thousand-kernel weight (TKW) and crop yield, therefore they have undergone strong selection since cereal was domesticated. Genetic dissection of the two traits will improve yield potential in crops. A quantitative trait locus significantly associated with wheat grain TKW was detected on chromosome 7AS flanked by a simple sequence repeat marker of Wmc17 in Chinese wheat 262 mini-core collection by genome-wide association study. Combined with the bulked segregant RNA-sequencing (BSR-seq) analysis of an F2 genetic segregation population with extremely different TKW traits, a candidate trehalose-6-phosphate phosphatase gene located at 135.0 Mb (CS V1.0), designated as TaTPP-7A, was identified. This gene was specifically expressed in developing grains and strongly influenced grain filling and size. Overexpression (OE) of TaTPP-7A in wheat enhanced grain TKW and wheat yield greatly. Detailed analysis revealed that OE of TaTPP-7A significantly increased the expression levels of starch synthesis- and senescence-related genes involved in abscisic acid (ABA) and ethylene pathways. Moreover, most of the sucrose metabolism and starch regulation-related genes were potentially regulated by SnRK1. In addition, TaTPP-7A is a crucial domestication- and breeding-targeted gene and it feedback regulates sucrose lysis, flux, and utilization in the grain endosperm mainly through the T6P-SnRK1 pathway and sugar-ABA interaction. Thus, we confirmed the T6P signalling pathway as the central regulatory system for sucrose allocation and source-sink interactions in wheat grains and propose that the trehalose pathway components have great potential to increase yields in cereal crops.

HSP90.2 promotes CO2 assimilation rate, grain weight and yield in wheat.

Wheat fixes CO2 by photosynthesis into kernels to nourish humankind. Improving the photosynthesis rate is a major driving force in assimilating atmospheric CO2 and guaranteeing food supply for human beings. Strategies for achieving the above goal need to be improved. Here, we report the cloning and mechanism of CO2 ASSIMILATION RATE AND KERNEL-ENHANCED 1 (CAKE1) from durum wheat (Triticum turgidum L. var. durum). The cake1 mutant displayed a lower photosynthesis rate with smaller grains. Genetic studies identified CAKE1 as HSP90.2-B, encoding cytosolic molecular chaperone folding nascent preproteins. The disturbance of HSP90.2 decreased leaf photosynthesis rate, kernel weight (KW) and yield. Nevertheless, HSP90.2 over-expression increased KW. HSP90.2 recruited and was essential for the chloroplast localization of nuclear-encoded photosynthesis units, for example PsbO. Actin microfilaments docked on the chloroplast surface interacted with HSP90.2 as a subcellular track towards chloroplasts. A natural variation in the hexaploid wheat HSP90.2-B promoter increased its transcription activity, enhanced photosynthesis rate and improved KW and yield. Our study illustrated an HSP90.2-Actin complex sorting client preproteins towards chloroplasts to promote CO2 assimilation and crop production. The beneficial haplotype of Hsp90.2 is rare in modern varieties and could be an excellent molecular switch promoting photosynthesis rate to increase yield in future elite wheat varieties.

Wheat NAC-A18 regulates grain starch and storage proteins synthesis and affects grain weight.

KEY MESSAGE: Wheat NAC-A18 regulates both starch and storage protein synthesis in the grain, and a haplotype with positive effects on grain weight showed increased frequency during wheat breeding in China. Starch and seed storage protein (SSP) directly affect the processing quality of wheat grain. The synthesis of starch and SSP are also regulated at the transcriptional level. However, only a few starch and SSP regulators have been identified in wheat. In this study, we discovered a NAC transcription factor, designated as NAC-A18, which acts as a regulator of both starch and SSP synthesis. NAC-A18, is predominately expressed in wheat developing grains, encodes a transcription factor localized in the nucleus, with both activation and repression domains. Ectopic expression of wheat NAC-A18 in rice significantly decreased starch accumulation and increased SSP accumulation and grain size and weight. Dual-luciferase reporter assays indicated that NAC-A18 could reduce the expression of TaGBSSI-A1 and TaGBSSI-A2, and enhance the expression of TaLMW-D6 and TaLMW-D1. A yeast one hybrid assay demonstrated that NAC-A18 bound directly to the cis-element "ACGCAA" in the promoters of TaLMW-D6 and TaLMW-D1. Further analysis indicated that two haplotypes were formed at NAC-A18, and that NAC-A18_h1 was a favorable haplotype correlated with higher thousand grain weight. Based on limited population data, NAC-A18_h1 underwent positive selection during Chinese wheat breeding. Our study demonstrates that wheat NAC-A18 regulates starch and SSP accumulation and grain size. A molecular marker was developed for the favorable allele for breeding applications.

Resistance of QYm.nau-2D to wheat yellow mosaic virus was derived from an alien introgression into common wheat.

KEY MESSAGE: The QYm.nau-2D locus conferring wheat yellow mosaic virus resistance is an exotic introgression and we developed 11 diagnostic markers tightly linked to QYm.nau-2D. Wheat yellow mosaic virus (WYMV) is a serious disease of winter wheat in China. Breeding resistant varieties is the most effective strategy for WYMV control. A WYMV resistant locus QYm.nau-2D on the chromosome arm 2DL has been repeatedly reported but the mapped region is large. In the present study, we screened recombinants using a biparental population and mapped QYm.nau-2D into an 18.8 Mb physical interval. By genome-wide association studies of 372 wheat varieties for WYMV resistance in four environments, we narrowed down QYm.nau-2D into a 16.4 Mb interval. Haplotype analysis indicated QYm.nau-2D were present as six different states due to recombination during hybridization breeding. QYm.nau-2D was finally mapped into a linkage block of 11.2 Mb. Chromosome painting using 2D specific probes and collinearity analysis among the published sequences corresponding to QYm.nau-2D region indicated the block was an exotic introgression. The Illumina-sequenced reads of four diploid Aegilops species were mapped to the sequence of Fielder, a variety having the introgression. The mapping reads were significantly increased at the putative introgression regions of Fielder. Ae. uniaristata (NN) had the highest mapping reads, suggesting that QYm.nau-2D was possibly an introgression from genome N. We investigated the agronomic performances of different haplotypes and observed no linkage drag of the alien introgression for the 15 tested traits. For marker-assisted selection of QYm.nau-2D, we developed 11 diagnostic markers tightly linked to the locus. This research provided a case study of an exotic introgression, which has been utilized in wheat improvement for WYMV resistance.

Optimization of single-tube nested PCR for the detection of Echinococcus spp.

Echinococcosis is a serious zoonotic life-threatening parasitic disease caused by metacestodes of Echinococcus spp., and appropriate sensitive diagnosis and genotyping techniques are required to detect infections and study the genetic characterization of Echinococcus spp. isolates. In this study, a single-tube nested PCR (STNPCR) method was developed and evaluated for the detection of Echinococcus spp. DNA based on the COI gene. STNPCR was 100 times more sensitive than conventional PCR and showed the same sensitivity to common nested PCR (NPCR); but with a lower risk of cross-contamination. The limit of detection of the developed STNPCR method was estimated to be 10 copies/µL of the recombinant standard plasmids of Echinococcus spp. COI gene. In clinical application, 8 cyst tissue samples and 12 calcification tissue samples were analysed by conventional PCR with outer and inner primers and resulted in 100.00% (8/8) and 8.33% (1/12), 100.00% (8/8) and 16.67% (2/12) positive reactions, respectively, while STNPCR and NPCR were all able to identify the presence of genomic DNA in 100.00% (8/8) and 83.33% (10/12) of the same samples. Due to its high sensitivity combined with the potential for the elimination of cross-contamination, the STNPCR method was suitable for epidemiological investigations and characteristic genetic studies of Echinococcus spp. tissue samples. The STNPCR method can effectively amplify low concentrations of genomic DNA from calcification samples and cyst residues infected with Echinococcus spp. Subsequently, the sequences of positive PCR products were obtained, which were useful for haplotype analysis, genetic diversity, and evolution studies of Echinococcus spp., and understanding of Echinococcus spp. dissemination and transmission among the hosts.

Identification and prevalence of fluke infection in yak and Tibetan sheep around Qinghai Lake, China.

Liver flukes (Fasciola spp.) and rumen flukes (Paramphistomum spp.) are significant parasites in livestock worldwide, and Fasciola spp. are considered an important zoonotic parasite. To our knowledge, there are no reports on fluke species identification and epidemiological prevalence in yak and Tibetan sheep around Qinghai Lake, China. Therefore, this study aimed to identify the major fluke species and determine the prevalence of fluke infections among yak and Tibetan sheep in this area. A total of 307 fecal samples were collected and fluke eggs identified using morphology and molecular methods. Our study is the first to display that the predominant fluke species were F. hepatica and P. leydeni in yak and Tibetan sheep around Qinghai Lake. The overall prevalence of fluke infections in yak and Tibetan sheep was 57.7% (177/307). Specifically, the prevalences of F. hepatica and P. leydeni were 15.0% (46/307) and 31.6% (97/307), respectively, and the co-infection of both species was 11.1% (34/307). No significant difference existed in the prevalence of overall fluke infection between yak and Tibetan sheep (p < 0.05). However, F. hepatica prevalence was significantly different in yak and Tibetan sheep (p < 0.05) but not P. leydeni. The findings of this study provide useful information about the current status of natural fluke invasion in yak and Tibetan sheep around Qinghai Lake, which could be important for monitoring and controlling these parasites in the region.

Genome-wide phylogenetic and genetic evolutionary analyses of mitochondria in Hypoderma bovis and H. sinense on the Qinghai-Tibetan Plateau.

Hypoderma bovis (H. bovis) and Hypoderma sinense (H. sinense) are insects that cause hypodermosis in yaks and Bos taurus. Hypodermosis is a severe skin condition that not only impairs the development of local animal husbandry but also poses threats to human health as a zoonosis. The Qinghai-Tibetan Plateau (QTP) is known as the "Roof of the World." Its unique geographical environment and climate conditions have supported the growth of a wide range of mammals, providing favorable conditions for Hypoderma spp. to complete their life cycles. In this study, the whole mitochondrial genomes of H. bovis and H. sinense collected from the QTP were sequenced and phylogenetically analyzed. We found that the whole genomes of H. bovis and H. sinense are 16,283 bp and 16,300 bp in length, respectively. Both the H. bovis and H. sinense genomes have 37 mitochondrial genes, which include two rRNA genes (16S rRNA and 12S rRNA), 22 tRNA genes, the control region (D-loop region), the light chain replication initiation region, and 13 protein-coding genes (PCGs). The phylogenetic tree generated based on the 13 PCGs revealed close phylogenetic relationships between H. sinense, H. bovis, and Hypoderma lineatum. A similar result was also found in our phylogenetic analysis based on 18S rRNA and 28S rRNA. However, analysis of cytochrome oxidase subunit I (COI) showed cluster of H. bovis, H. sinense, and Cuterebra spp. on the same branch, all belonging to Oestridae. The differentiation time generated based on 13 PCGs indicates that H. bovis and H. sinense differentiated and formed ~4.69 million years ago (Mya) and ~4.06 Mya, respectively. This timing coincides with the differentiation and appearance of yak and Bos taurus in the Pliocene (~4.7 Mya), indicating that the parasites and mammals diverged in close temporal proximity. Of note, this period also witnessed a rapid uplift of the QTP, causing significant climate and environmental changes. Thus, we conjecture that the differentiation of Hypoderma spp. is potentially related to the differentiation of their host species, as well as climate changes caused by the uplift of the QTP. Overall, our study can provide valuable data to support further studies on the phylogeny and differentiation of Hypoderma spp. on the QTP.

Transcriptome Analysis of Roots from Wheat (Triticum aestivum L.) Varieties in Response to Drought Stress.

Under climate change, drought is one of the most limiting factors that influences wheat (Triticum aestivum L.) production. Exploring stress-related genes is vital for wheat breeding. To identify genes related to the drought tolerance response, two common wheat cultivars, Zhengmai 366 (ZM366) and Chuanmai 42 (CM42), were selected based on their obvious difference in root length under 15% PEG-6000 treatment. The root length of the ZM366 cultivar was significantly longer than that of CM42. Stress-related genes were identified by RNA-seq in samples treated with 15% PEG-6000 for 7 days. In total, 11,083 differentially expressed genes (DEGs) and numerous single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) were identified. GO enrichment analysis revealed that the upregulated genes were mainly related to the response to water, acidic chemicals, oxygen-containing compounds, inorganic substances, and abiotic stimuli. Among the DEGs, the expression levels of 16 genes in ZM366 were higher than those in CM42 after the 15% PEG-6000 treatment based on RT-qPCR. Furthermore, EMS-induced mutants in Kronos (T. turgidum L.) of 4 representative DEGs possessed longer roots than the WT after the 15% PEG-6000 treatment. Altogether, the drought stress genes identified in this study represent useful gene resources for wheat breeding.

Integrated Analysis of Metabolome and Transcriptome Reveals Insights for Low Phosphorus Tolerance in Wheat Seedling.

Low phosphorus (LP) stress leads to a significant reduction in wheat yield, primarily in the reduction of biomass, the number of tillers and spike grains, the delay in heading and flowering, and the inhibition of starch synthesis and grouting. However, the differences in regulatory pathway responses to low phosphorus stress among different wheat genotypes are still largely unknown. In this study, metabolome and transcriptome analyses of G28 (LP-tolerant) and L143 (LP-sensitive) wheat varieties after 72 h of normal phosphorus (CK) and LP stress were performed. A total of 181 and 163 differentially accumulated metabolites (DAMs) were detected for G28CK vs. G28LP and L143CK vs. L143LP, respectively. Notably, the expression of pilocarpine (C07474) in G28CK vs. G28LP was significantly downregulated 4.77-fold, while the expression of neochlorogenic acid (C17147) in L143CK vs. L143LP was significantly upregulated 2.34-fold. A total of 4023 differentially expressed genes (DEGs) were acquired between G28 and L143, of which 1120 DEGs were considered as the core DEGs of LP tolerance of wheat after LP treatment. The integration of metabolomics and transcriptomic data further revealed that the LP tolerance of wheat was closely related to 15 metabolites and 18 key genes in the sugar and amino acid metabolism pathway. The oxidative phosphorylation pathway was enriched to four ATPases, two cytochrome c reductase genes, and fumaric acid under LP treatment. Moreover, PHT1;1, TFs (ARFA, WRKY40, MYB4, MYB85), and IAA20 genes were related to the Pi starvation stress of wheat roots. Therefore, the differences in LP tolerance of different wheat varieties were related to energy metabolism, amino acid metabolism, phytohormones, and PHT proteins, and precisely regulated by the levels of various molecular pathways to adapt to Pi starvation stress. Taken together, this study may help to reveal the complex regulatory process of wheat adaptation to Pi starvation and provide new genetic clues for further study on improving plant Pi utilization efficiency.

TaTIP41 and TaTAP46 positively regulate drought tolerance in wheat by inhibiting PP2A activity.

Drought is a major environmental stress limiting global wheat (Triticum aestivum) production. Exploring drought tolerance genes is important for improving drought adaptation in this crop. Here, we cloned and characterized TaTIP41, a novel drought tolerance gene in wheat. TaTIP41 is a putative conserved component of target of rapamycin (TOR) signaling, and the TaTIP41 homoeologs were expressed in response to drought stress and abscisic acid (ABA). The overexpression of TaTIP41 enhanced drought tolerance and the ABA response, including ABA-induced stomatal closure, while its downregulation using RNA interference (RNAi) had the opposite effect. Furthermore, TaTIP41 physically interacted with TaTAP46, another conserved component of TOR signaling. Like TaTIP41, TaTAP46 positively regulated drought tolerance. Furthermore, TaTIP41 and TaTAP46 interacted with type-2A protein phosphatase (PP2A) catalytic subunits, such as TaPP2A-2, and inhibited their enzymatic activities. Silencing TaPP2A-2 improved drought tolerance in wheat. Together, our findings provide new insights into the roles of TaTIP41 and TaTAP46 in the drought tolerance and ABA response in wheat, and their potential application in improving wheat environmental adaptability.

DIW1 encoding a clade I PP2C phosphatase negatively regulates drought tolerance by de-phosphorylating TaSnRK1.1 in wheat.

Drought seriously impacts wheat production (Triticum aestivum L.), while the exploitation and utilization of genes for drought tolerance are insufficient. Leaf wilting is a direct reflection of drought tolerance in plants. Clade A PP2Cs are abscisic acid (ABA) co-receptors playing vital roles in the ABA signaling pathway, regulating drought response. However, the roles of other clade PP2Cs in drought tolerance, especially in wheat, remain largely unknown. Here, we identified a gain-of-function drought-induced wilting 1 (DIW1) gene from the wheat Aikang 58 mutant library by map-based cloning, which encodes a clade I protein phosphatase 2C (TaPP2C158) with enhanced protein phosphatase activity. Phenotypic analysis of overexpression and CRISPR/Cas9 mutant lines demonstrated that DIW1/TaPP2C158 is a negative regulator responsible for drought resistance. We found that TaPP2C158 directly interacts with TaSnRK1.1 and de-phosphorylates it, thus inactivating the TaSnRK1.1-TaAREB3 pathway. TaPP2C158 protein phosphatase activity is negatively correlated with ABA signaling. Association analysis suggested that C-terminal variation of TaPP2C158 changing protein phosphatase activity is highly correlated with the canopy temperature, and seedling survival rate under drought stress. Our data suggest that the favorable allele with lower phosphatase activity of TaPP2C158 has been positively selected in Chinese breeding history. This work benefits us in understanding the molecular mechanism of wheat drought tolerance, and provides elite genetic resources and molecular markers for improving wheat drought tolerance.

The wheat ABA receptor gene TaPYL1-1B contributes to drought tolerance and grain yield by increasing water-use efficiency.

The role of abscisic acid (ABA) receptors, PYR1/PYL/RCAR (PYLs), is well established in ABA signalling and plant drought response, but limited research has explored the regulation of wheat PYLs in this process, especially the effects of their allelic variations on drought tolerance or grain yield. Here, we found that the overexpression of a TaABFs-regulated PYL gene, TaPYL1-1B, exhibited higher ABA sensitivity, photosynthetic capacity and water-use efficiency (WUE), all contributed to higher drought tolerance than that of wild-type plants. This heightened water-saving mechanism further increased grain yield and protected productivity during water deficit. Candidate gene association analysis revealed that a favourable allele TaPYL1-1BIn-442 , carrying an MYB recognition site insertion in the promoter, is targeted by TaMYB70 and confers enhanced expression of TaPYL1-1B in drought-tolerant genotypes. More importantly, an increase in frequency of the TaPYL1-1BIn-442 allele over decades among modern Chinese cultivars and its association with high thousand-kernel weight together demonstrated that it was artificially selected during wheat improvement efforts. Taken together, our findings illuminate the role of TaPYL1-1B plays in coordinating drought tolerance and grain yield. In particular, the allelic variant TaPYL1-1BIn-442 substantially contributes to enhanced drought tolerance while maintaining high yield, and thus represents a valuable genetic target for engineering drought-tolerant wheat germplasm.

The miR319/TaGAMYB3 module regulates plant architecture and improves grain yield in common wheat (Triticum aestivum).

Plant architecture is a key determinant of crop productivity and adaptation. The highly conserved microRNA319 (miR319) family functions in various biological processes, but little is known about how miR319 regulates plant architecture in wheat (Triticum aestivum). Here, we determined that the miR319/TaGAMYB3 module controls plant architecture and grain yield in common wheat. Repressing tae-miR319 using short tandem target mimics resulted in favorable plant architecture traits, including increased plant height, reduced tiller number, enlarged spikes and flag leaves, and thicker culms, as well as enhanced grain yield in field plot tests. Overexpressing tae-miR319 had the opposite effects on plant architecture and grain yield. Although both TaPCF8 and TaGAMYB3 were identified as miR319 target genes, genetic complementation assays demonstrated that only miR319-resistant TaGAMYB3 (rTaGAMYB3) abolished tae-miR319-mediated growth inhibition of flag leaves and spikes. TaGAMYB3 functions as a transcriptional activator of downstream genes, including TaPSKR1, TaXTH23, TaMADS5 and TaMADS51, by binding to their promoters. Furthermore, TaGAMYB3 physically interacts with TaBA1, an important regulator of spike development, to additively activate the transcription of downstream genes such as TaMADS5. Our findings provide insight into how the miR319/TaGAMYB3 module regulates plant architecture and improves grain yield in common wheat.

TaGSNE, a WRKY transcription factor, overcomes the trade-off between grain size and grain number in common wheat and is associated with root development.

Wheat is one of the world's major staple food crops, and breeding for improvement of grain yield is a priority under the scenarios of climate change and population growth. WRKY transcription factors are multifaceted regulators in plant growth, development, and responses to environmental stimuli. In this study, we identify the WRKY gene TaGSNE (Grain Size and Number Enhancer) in common wheat, and find that it has relatively high expression in leaves and roots, and is induced by multiple abiotic stresses. Eleven single-nucleotide polymorphisms were identified in TaGSNE, forming two haplotypes in multiple germplasm collections, named as TaGSNE-Hap-1 and TaGSNE-Hap-2. In a range of different environments, TaGSNE-Hap-2 was significantly associated with increases in thousand-grain weight (TGW; 3.0%) and spikelet number per spike (4.1%), as well as with deeper roots (10.1%) and increased root dry weight (8.3%) at the mid-grain-filling stage, and these were confirmed in backcross introgression populations. Furthermore, transgenic rice lines overexpressing TaGSNE had larger panicles, more grains, increased grain size, and increased grain yield relative to the wild-type control. Analysis of geographic and temporal distributions revealed that TaGSNE-Hap-2 is positively selected in China and Pakistan, and TaGSNE-Hap-1 in Europe. Our findings demonstrate that TaGSNE overcomes the trade-off between TGW/grain size and grain number, leading us to conclude that these elite haplotypes and their functional markers could be utilized in marker-assisted selection for breeding high-yielding varieties.

Effects of rocuronium dosage on intraoperative neurophysiological monitoring in patients undergoing spinal surgery.

WHAT IS KNOWN AND OBJECTIVE: Intraoperative neurophysiological monitoring (IONM) has been widely used in clinical practice. Therefore, the influence of neuromuscular blockers essential for spinal anaesthesia on IONM is worthy of our attention, but no randomized study has evaluated the dose-response effect. This study investigated the effects of different doses of rocuronium bromide on the intraoperative monitoring of motor evoked potentials (MEPs). METHODS: We conducted a randomized, double-blind trial to assess the effects of three rocuronium bromide doses (6.0, 9.0, 12 µg·kg-1 ·min-1 ) combined with intravenous infusion of propofol 6-8 mg·kg-1 ·h-1 and remifentanil 10 µg·kg-1 ·h-1 on the amplitudes of somatosensory evoked potentials (SEPs) and MEPs at the time of the baseline recording (T1 ), before pedicle screw placement (T2 ) and before spinal canal decompression (T3 ). Secondary outcomes included measurement of neuromuscular function, the occurrence of unexpected intraoperative body movement and recovery of spontaneous breathing. RESULTS AND DISCUSSION: A total of 123 patients were enrolled, and 120 patients were ultimately analysed. No differences were observed in the amplitude of SEPs among the three groups (p > 0.05). The MEP amplitude differences at T1 , T2 and T3 in all limbs did not differ in patients receiving rocuronium at 6.0 µg·kg-1 ·min-1 and 9.0 µg·kg-1 ·min-1 (p > 0.05). However, when rocuronium was administered at 12.0 µg·kg-1 ·min-1 , MEP amplitudes at the time point T3 were significantly attenuated compared with the time points T1 and T2 in both right upper limb and left lower limb (p = 0.002, p = 0.025, respectively). In patients treated with rocuronium 6.0 µg·kg-1 ·min-1 , the incidence of unexpected body movement was significantly higher (p = 0.026), and the train-of-four count (TOF count) showed a significant increase at T2 and T3 (p < 0.001) compared to other doses. WHAT IS NEW AND CONCLUSION: Rocuronium bromide at a rate of 9.0 µg·kg-1 ·min-1 provided suitable and adequate muscle relaxation without inhibiting IONM; thus, this dose is recommended for spinal surgery.

InDels Identification and Association Analysis with Spike and Awn Length in Chinese Wheat Mini-Core Collection.

Diversity surveys of germplasm are important for gaining insight into the genomic basis for crop improvement; especially InDels, which are poorly understood in hexaploid common wheat. Here, we describe a map of 89,923 InDels from exome sequencing of 262 accessions of a Chinese wheat mini-core collection. Population structure analysis, principal component analysis and selective sweep analysis between landraces and cultivars were performed. Further genome-wide association study (GWAS) identified five QTL (Quantitative Trait Loci) that were associated with spike length, two of them, on chromosomes 2B and 6A, were detected in 10 phenotypic data sets. Assisted with RNA-seq data, we identified 14 and 21 genes, respectively that expressed in spike and rachis within the two QTL regions that can be further investigated for candidate genes discovery. Moreover, InDels were found to be associated with awn length on chromosomes 5A, 6B and 4A, which overlapped with previously reported genetic loci B1 (Tipped 1), B2 (Tipped 2) and Hd (Hooded). One of the genes TaAGL6 that was previously shown to affect floral organ development was found at the B2 locus to affect awn length development. Our study shows that trait-associated InDels may contribute to wheat improvement and may be valuable molecular markers for future wheat breeding.