Morphological, anatomical, and transcriptomics analysis reveals the regulatory mechanisms of cassava plant height development.

BACKGROUND: Cassava is one of three major potato crops and the sixth most important food crop globally. Improving yield remains a primary aim in cassava breeding. Notably, plant height significantly impacts the yield and quality of crops; however, the mechanisms underlying cassava plant height development are yet to be elucidated. RESULTS: In this study, we investigated the mechanisms responsible for cassava plant height development using phenotypic, anatomical, and transcriptomic analyses. Phenotypic and anatomical analysis revealed that compared to the high-stem cassava cultivar, the dwarf-stem cassava cultivar exhibited a significant reduction in plant height and a notable increase in internode tissue xylem area. Meanwhile, physiological analysis demonstrated that the lignin content of dwarf cassava was significantly higher than that of high cassava. Notably, transcriptome analysis of internode tissues identified several differentially expressed genes involved in cell wall synthesis and expansion, plant hormone signal transduction, phenylpropanoid biosynthesis, and flavonoid biosynthesis between the two cassava cultivars. CONCLUSIONS: Our findings suggest that internode tissue cell division, secondary wall lignification, and hormone-related gene expression play important roles in cassava plant height development. Ultimately, this study provides new insights into the mechanisms of plant height morphogenesis in cassava and identifies candidate regulatory genes associated with plant height that can serve as valuable genetic resources for future crop dwarfing breeding.

Ferroptosis inhibitor liproxstatin-1 alleviates metabolic dysfunction-associated fatty liver disease in mice: potential involvement of PANoptosis.

Ferroptosis is a new form of regulated cell death characterized by excessive iron accumulation and uncontrollable lipid peroxidation. The role of ferroptosis in metabolic dysfunction-associated fatty liver disease (MAFLD) is not fully elucidated. In this study we compared the therapeutic effects of ferroptosis inhibitor liproxstatin-1 (LPT1) and iron chelator deferiprone (DFP) in MAFLD mouse models. This model was established in mice by feeding a high-fat diet with 30% fructose in water (HFHF) for 16 weeks. The mice then received LPT1 (10 mg·kg-1·d-1, ip) or DFP (100 mg·kg-1·d-1, ig) for another 2 weeks. We showed that both LPT1 and DFP treatment blocked the ferroptosis markers ACSL4 and ALOX15 in MAFLD mice. Furthermore, LPT1 treatment significantly reduced the liver levels of triglycerides and cholesterol, lipid peroxidation markers 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA), and ameliorated the expression of lipid synthesis/oxidation genes (Pparα, Scd1, Fasn, Hmgcr and Cpt1a), insulin resistance, mitochondrial ROS content and liver fibrosis. Importantly, LPT1 treatment potently inhibited hepatic apoptosis (Bax/Bcl-xL ratio and TUNEL+ cell number), pyroptosis (cleavages of Caspase-1 and GSDMD) and necroptosis (phosphorylation of MLKL). Moreover, LPT1 treatment markedly inhibited cleavages of PANoptosis-related caspase-8 and caspase-6 in MAFLD mouse liver. In an in vitro MAFLD model, treatment with LPT1 (100 nM) prevented cultured hepatocyte against cell death induced by pro-PANoptosis molecules (TNF-α, LPS and nigericin) upon lipid stress. On the contrary, DFP treatment only mildly attenuated hepatic inflammation but failed to alleviate lipid deposition, insulin resistance, apoptosis, pyroptosis and necroptosis in MAFLD mice. We conclude that ferroptosis inhibitor LPT1 protects against steatosis and steatohepatitis in MAFLD mice, which may involve regulation of PANoptosis, a coordinated cell death pathway that involves apoptosis, pyroptosis and necroptosis. These results suggest a potential link between ferroptosis and PANoptosis.

First report of shoot and leaf blight caused by Botryosphaeria dothidea on Taxus × media in Sichuan province, China.

The genus Taxus is the natural material of the anticancer drug paclitaxel (Xiong et al. 2021). Harvesting sources of paclitaxel from the wild has greatly decreased the population of these trees. One of the taxus species, Taxus × media Rehder, a natural hybrid of taxus trees, has a higher paclitaxel content (Zhou et al. 2019). It has been introduced and cultivated in Sichuan, Chongqing, Yunnan, Zhejiang, Jiangxi, and other places in China. In 2021, approximately 20% of T. media (an average 30% of the affected area per tree) showed obvious shoot and leaf blight symptoms in a plantation of taxus trees (about 40 ha of the planting area), located in Sandaoyan county, Sichuan province, China (GPS, 103°94'60″N, 30°84'97″E). Initially, brown necrotic spots appeared on shoots. Gradually, the spots increased in number, expanded to the leaf attached to the branch, and caused wilting of the shoots and leaves. To identify the pathogen, symptomatic samples were randomly collected. Lesion margins of the diseased leaves and barks were surface sterilized for 1 min in 75% ethanol, rinsed with sterile distilled water three times, dried with sterile filter paper, placed on potato dextrose agar (PDA) amended with streptomycin sulfate (50 mg/liter), and incubated at 28°C in the dark. Six purified fungal isolates were obtained. Collected isolates with similar morphology were described as Botryosphaeria spp. (Zhang et al. 2021). The colonies were initially white, gradually became dark gray with dense erial mycelium after 5 days, and formed black pycnidia (Dimensions, 121.3 to 134.6 µm, n = 5) after 16 days. Conidia were fusiform, aseptate, transparent, and thin-walled (23.6 ± 1.2 × 7.27 ± 1.3 µm, n = 50), similar to B. dothidea (Hattori et al. 2021). For pathogenicity testing, ten 2-year-old seedlings of T. media were selected. Fungal cakes of the isolate Tmsdy-2 were applied to the punctured stems of seedlings and covered with Parafilm. Pieces of sterile medium were used as controls. All the seedlings were incubated at 25 ± 2°C, 50% relative humidity, and 16 h of light in a greenhouse. Four days later, the inoculated seedlings developed brown spots and were blighted in 14 days, with symptoms similar to the original diseased plants. The controls remained healthy. The same fungus was reisolated from the infected tissues and subsequently identified by morphological characteristics and DNA sequence analysis. The pathogenicity test was repeated three times with similar results, confirming Koch's postulates. For molecular identification, the DNA of the isolates was extracted using a Quick-DNA Extraction Kit (Tiangen Biotech, Beijing). The ITS, LSU, SSU, TUB2, and TEF 1-α genes were amplified with the primer pairs ITS1/ITS4, LR0R/LR05, NS1/NS4 (Li et al. 2018), Bt2a/Bt2b, and EF1-728F/EF1-986R (Hattori et al. 2021), respectively. The generated sequences were deposited in GenBank with accession numbers OQ179939 (ITS), OQ179940 (LSU), OQ179942 (SSU), OQ268596 (TUB2), and OQ268597 (TEF 1-α). BLAST analyses showed >99.65% identity with previously deposited sequences of B. dothidea in GenBank. Based on the maximum likelihood method, phylogenetic analysis revealed 100% bootstrap support values with B. dothidea. The fungus was identified as B. dothidea based on morphological and multilocus phylogenetic analyses. To our knowledge, this is the first report of B. dothidea causing shoot and leaf blight of T. media in China. These results will contribute to developing control strategies for this disease.

Lopinavir-ritonavir alone or combined with arbidol in the treatment of 73 hospitalized patients with COVID-19: A pilot retrospective study.

OBJECTIVES: This study aimed to evaluate the antiviral efficacy of lopinavir-ritonavir alone or combined with arbidol in the treatment of hospitalized patients with common coronavirus disease-19 (COVID-19). MATERIALS AND METHODS: In this retrospective observational study, hospitalized COVID-19 patients were identified and divided into two groups based on the antiviral agents during their hospitalization. Patients in group LR were treated with lopinavir-ritonavir 400 mg/100 mg, twice a day, while patients in group LR+Ar were treated with lopinavir-ritonavir 400 mg/100 mg twice a day and arbidol 200 mg three times a day for at least 3 days. Data from these patients were collected from electronic medical record management system. RESULTS: 73 patients were divided into two groups: group LR (34 cases) and group LR+Ar (39 cases), according to the antiviral agents. The overall cure rate of COVID-19 in group LR+Ar and group LR were 92.3% and 97.1%, respectively, with no significant difference (p = 0.62). In a modified intention-to-treat analysis, lopinavir-ritonavir combined with arbidol led to a median time of hospital stay that was shorter by 1.5 days than in group LR (12.5 days vs. 14 days). The percentages of -COVID-19 RNA clearance was 92.3 in group LR and 97.1 in group LR+Ar which was similar to the cure rate. The median time to nucleic acid turning negative = (date of first negative PCR test) - (date of last positive PCR test) was 8.0 days in both groups with no significant difference (p = 0.59). Treatment of lopinavir-ritonavir combined with arbidol did not significantly accelerate main symptom improvement and promote the image absorption of pulmonary inflammation. CONCLUSION: No benefit was observed in the antiviral effect of lopinavir-ritonavir combined with arbidol compared with lopinavir-ritonavir alone in the hospitalized patients with COVID-19. More clinical observations in COVID-19 patients may help to confirm or exclude the effect of antiviral agents.

The detection and analysis of differential regulatory communities in lung cancer.

The tumorgenesis process of lung cancer involves the regulatory dysfunctions of multiple pathways. Although many signaling pathways have been identified to be associated with lung cancer, there are little quantitative models of how inactions between genes change during the process from normal to cancer. These changes belong to different dynamic co-expressions patterns. We quantitatively analyzed differential co-expression of gene pairs in four datasets. Each dataset included a large number of lung cancer and normal samples. By overlapping their results, we got 14 highly confident gene pairs with consistent co-expression change patterns. Some of they, such as ARHGAP30 and GIMAP4, had been recorded in STRING network database while some of them were novel discoveries, such as C9orf135 and MORN5, TEKT1 and TSPAN1 were positively correlated in both normal and cancer but more correlated in normal than cancer. These gene pairs revealed the underlying mechanisms of lung cancer occurrence.

Design, synthesis and biological evaluation of acridone analogues as novel STING receptor agonists.

STING (Stimulator of Interferon Genes) has become a focal point in immunology research and a target in drug discovery. The discovery of a potent human-STING agonist is expected to revolutionize current anti-virus or cancer immunotherapy. Inspired by the structure and function of murine STING-specific agonists (DMXAA and CMA), we rationally designed and synthesized four series of novel compounds for the enhancement of human sensitivity. In the cell-based assay, we identified six compounds from all the synthetic small molecules: 2g, 9g, and 12b are STING agonists that are efficacious across species, and all have the skeleton of acridone; 1b, 1c, and 12c just function in the murine STING pathway. Notably, 12b exhibits the best activity among the six agonists, and its inductions of both human and murine STING-dependent signalling are similar to that of 2'3'-cGAMP, which is a well-known STING inducer. While a protein assay indicated that 2 g, 9 g, and 12b could activate the pathway by directly binding human STING, 12b also displayed the strongest binding affinity. Additionally, our studies show that 12b can induce faster, more powerful, and more durable responses of assorted cytokines in a native system than 2'3'-cGAMP. Consequently, our team is the first to successfully modify murine STING agonists to obtain human sensitivity, and these results suggest that 12b is a potent direct-human-STING agonist. Additionally, the acridone analogues demonstrate tremendous potential in the treatment of tumours or viral infections.

Transcriptional reference map of hormone responses in wheat spikes.

BACKGROUND: Phytohormones are key regulators of plant growth, development, and signalling networks involved in responses to diverse biotic and abiotic stresses. Transcriptional reference maps of hormone responses have been reported for several model plant species such as Arabidopsis thaliana, Oryza sativa, and Brachypodium distachyon. However, because of species differences and the complexity of the wheat genome, these transcriptome data are not appropriate reference material for wheat studies. RESULTS: We comprehensively analysed the transcriptomic responses in wheat spikes to seven phytohormones, including indole acetic acid (IAA), gibberellic acid (GA), abscisic acid (ABA), ethylene (ET), cytokinin (CK), salicylic acid (SA), and methyl jasmonic acid (MeJA). A total of 3386 genes were differentially expressed at 24 h after the hormone treatments. Furthermore, 22.7% of these genes exhibited overlapping transcriptional responses for at least two hormones, implying there is crosstalk among phytohormones. We subsequently identified genes with expression levels that were significantly and differentially induced by a specific phytohormone (i.e., hormone-specific responses). The data for these hormone-responsive genes were then compared with the transcriptome data for wheat spikes exposed to biotic (Fusarium head blight) and abiotic (water deficit) stresses. CONCLUSION: Our data were used to develop a transcriptional reference map of hormone responses in wheat spikes.

Re-acquisition of the brittle rachis trait via a transposon insertion in domestication gene Q during wheat de-domestication.

De-domestication is a unique evolutionary process during which crops re-acquire wild-like traits to survive and persist in agricultural fields without the need for human cultivation. The re-acquisition of seed dispersal mechanisms is crucial for crop de-domestication. Common wheat is an important cereal crop worldwide. Tibetan semi-wild wheat is a potential de-domesticated common wheat subspecies. However, the crucial genes responsible for its brittle rachis trait have not been identified. Genetic mapping, functional analyses and phylogenetic analyses were completed to identify the gene associated with Qbr.sau-5A, which is a major locus for the brittle rachis trait of Tibetan semi-wild wheat. The cloned Qbr.sau-5A gene is a new Q allele (Qt ) with a 161-bp transposon insertion in exon 5. Although Qt is expressed normally, its encoded peptide lacks some key features of the APETALA2 family. The abnormal functions of Qt in developing wheat spikes result in brittle rachises. Phylogenetic and genotyping analyses confirmed that Qt originated from Q in common wheat and is naturally distributed only in Tibetan semi-wild wheat populations. The identification of Qt provides new evidence regarding the origin of Tibetan semi-wild wheat, and new insights into the re-acquisition of wild traits during crop de-domestication.

Design, Synthesis and Biological Evaluation of 1-Phenyl-2-(phenylamino) Ethanone Derivatives as Novel MCR-1 Inhibitors.

Polymyxins are considered to be the last-line antibiotics that are used to treat infections caused by multidrug-resistant (MDR) gram-negative bacteria; however, the plasmid-mediated transferable colistin resistance gene (mcr-1) has rendered polymyxins ineffective. Therefore, the protein encoded by mcr-1, MCR-1, could be a target for structure-based design of inhibitors to tackle polymyxins resistance. Here, we identified racemic compound 3 as a potential MCR-1 inhibitor by virtual screening, and 26 compound 3 derivatives were synthesized and evaluated in vitro. In the cell-based assay, compound 6g, 6h, 6i, 6n, 6p, 6q, and 6r displayed more potent activity than compound 3. Notably, 25 µΜ of compound 6p or 6q combined with 2 µg·mL-1 colistin could completely inhibit the growth of BL21(DE3) expressing mcr-1, which exhibited the most potent activity. In the enzymatic assay, we elucidate that 6p and 6q could target the MCR-1 to inhibit the activity of the protein. Additionally, a molecular docking study showed that 6p and 6q could interact with Glu246 and Thr285 via hydrogen bonds and occupy well the cavity of the MCR-1 protein. These results may provide a potential avenue to overcome colistin resistance, and provide some valuable information for further investigation on MCR-1 inhibitors.

Alternative splicing results in a lack of starch synthase IIa-D in Chinese wheat landrace.

We evaluated the SGP-1 protein composition of 368 Chinese wheat landraces using SDS-PAGE. The SGP-D1 null type was identified in three accessions (Xiaoqingmang, Pushanbamai, and P119). An 18-bp deletion and 9-bp variation were found at the junction region of the 7th intron and 8th exon, leading to deletion of the intron-exon junction recognition site AG when aligned the 8261-bp DNA sequence of TaSSIIa-D in Pushanbamai with that of Chinese Spring. Four cDNA types with mis-spliced isoforms were subsequently detected through amplification of TaSSIIa-D cDNAs. Among these, nine type II cDNAs with a 16-bp deletion in the 8th exon were detected, indicating that the major transcriptional pattern of TaSSIIa in Pushanbamai is type II. In the type IV cDNA, a 97-bp sequence remains undeleted in the end of the 5th exon. The amylose content in Pushanbamai was significantly higher than that in all control lines under field conditions, which suggested that deletion of SGP-D1 has an efficient impact on amylose content. As the TaSSIIa gene plays an important role in regulating the content of amylose, it is anticipated that these natural variants of TaSSIIa-D will provide useful resources for quality improvement in wheat.

Fusarium graminearum ATP-Binding Cassette Transporter Gene FgABCC9 Is Required for Its Transportation of Salicylic Acid, Fungicide Resistance, Mycelial Growth and Pathogenicity towards Wheat.

ATP-binding cassette (ABC) transporters hydrolyze ATP to transport a wide range of substrates. Fusarium graminearum is a major causal agent of Fusarium head blight, which is a severe disease in wheat worldwide. FgABCC9 (FG05_07325) encodes an ABC-C (ABC transporter family C) transporter in F. graminearum, which was highly expressed during the infection in wheat and was up-regulated by the plant defense hormone salicylic acid (SA) and the fungicide tebuconazole. The predicted tertiary structure of the FgABCC9 protein was consistent with the schematic of the ABC exporter. Deletion of FgABCC9 resulted in decreased mycelial growth, increased sensitivity to SA and tebuconazole, reduced accumulation of deoxynivalenol (DON), and less pathogenicity towards wheat. Re-introduction of a functional FgABCC9 gene into ΔFgABCC9 recovered the phenotypes of the wild type strain. Transgenic expression of FgABCC9 in Arabidopsis thaliana increased the accumulation of SA in its leaves without activating SA signaling, which suggests that FgABCC9 functions as an SA exporter. Taken together, FgABCC9 encodes an ABC exporter, which is critical for fungal exportation of SA, response to tebuconazole, mycelial growth, and pathogenicity towards wheat.

Transposon insertion resulted in the silencing of Wx-B1n in Chinese wheat landraces.

KEY MESSAGE: A novel Wx-B1 allele was characterized; a transposon insertion resulted in the loss of its function, which is different from the previously reported gene silencing mechanisms at the Wx-B1 locus. The waxy protein composition of 53 Chinese wheat landraces was analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional gel electrophoresis; of these, 10 did not show the expression of Wx-A1 (four accession) or Wx-B1 (six accessions) protein. The results of molecular marker detection revealed that the Wx-B1 allele (Wx-B1n) showed normal expression, inconsistent with the findings of SDS-PAGE for the Xiaobaipi accession. Further cloning of the 9160-bp region covering the Wx-B1 coding region and 3'-downstream region revealed that a 2178-bp transposon fragment had been inserted at 2462 bp within the tenth exon of Wx-B1n ORF, leading to the absence of Wx-B1 protein. Sequence analysis indicated that the insertion possessed the structural features of invert repeat and target repeat elements, we deduced that it was a transposon. Further PCR analysis revealed that this fragment had moved, but not copied itself, from 3B chromosome to the current location in Wx-B1n. Therefore, the reason for the inactivation of Wx-B1n was considerably different from those for the inactivation of Wx-B1b, Wx-B1k, and Wx-B1m; to our knowledge, this kind of structural mutation has never been reported in Wx-B1 alleles. This novel allele is interesting, because it was not associated with the deletion of other quality-related genes included in the 67 kb region lost with the common null allele Wx-B1b. The null Wx-B1n might be useful for investigating gene inactivation and expression as well as for enriching the genetic resource pool for the modification of the amylose/amylopectin ratio, thereby improving wheat quality.

Identification and characterization of genes on a single subgenome in the hexaploid wheat (Triticum aestivum L.) genotype 'Chinese Spring'.

Gene loss during the formation of hexaploid bread wheat has been repeatedly reported. However, our knowledge on genome-wide analysis of the genes present on a single subgenome (SSG) in bread wheat is still limited. In this study, by analysing the 'Chinese Spring' chromosome arm shotgun sequences together with high-confidence gene models, we detected 433 genes on a SSG. Greater gene loss was observed in A and D subgenomes compared with B subgenome. More than 79% of the orthologs for these SSG genes were detected in diploid and tetraploid relatives of hexaploid wheat. Unexpectedly, no bias in expression breadth or in the distribution patterns of GO (gene ontology) terms for these genes was detected among the high-confidence genes. Further, network and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses indicated that most of these genes were not functionally related to each other. Interestingly, 30.7% of these SSG genes were most highly expressed in root, showing biased distribution given the distribution of the whole high-confidence genes. Collectively, these results facilitate our understanding of the loss of the genes that were retained in a SSG during the formation of hexaploid wheat.

Identification of quantitative trait loci for seedling root traits from Tibetan semi-wild wheat (Triticum aestivum subsp. tibetanum).

As a primitive hexaploid wheat resource distributed only in Tibet, Tibetan semi-wild wheat (Triticum aestivum subsp. tibetanum Shao) possesses unique characteristics that could be exploited in wheat breeding programs. Its good root system could offer a stable platform for above-ground components. To detect possible excellent locus for root traits from Tibetan semi-wild wheat, we identified QTLs for root traits using a recombinant inbred line population derived from a cross between Tibetan semi-wild wheat Q1028 and Zhengmai 9023. A total of 15 QTLs on eight chromosomes were detected, including four major QTLs, QMrl.sau-7B, QTrl.sau-4B, QAd.sau-7A, and QSa.sau-4B. The phenotypic variation explained by each of these QTLs ranges from 5.67% to 16.68%. Positive alleles of six QTLs were derived from Q1028. Several novel QTLs for root traits were identified. In addition, significant correlations were detected amongst root traits and agronomic traits. Taken together, these results suggest that Tibetan semi-wild wheat and the newly identified novel QTLs could be useful in future breeding programs.

[Early intellectual developmental outcome of late preterm infants].

OBJECTIVE: To investigate the early intellectual developmental outcome of late preterm infants. METHODS: A total of 106 late preterm infants with a gestational age of 34-36+6 weeks who were admitted to the neonatal ward between January 2012 and January 2015, cured, discharged, and regularly followed up at the outpatient service for high-risk children were enrolled as the preterm group. A total of 120 healthy full-term infants during the same period were randomly selected as the term group. Neonatal behavioral neurological assessment (NBNA) was performed for late preterm infants at a corrected gestational age of 40 weeks and full-term infants at a gestational age of 40 weeks. The Gesell Developmental Scale was used for late preterm infants at a corrected age of 3, 6, and 12 months and full-term infants at an age of 3, 6, and 12 months. RESULTS: The preterm group had an NBNA score of <37 and a significantly lower NBNA score than the term group (P<0.05). At the corrected age of 3 months, the preterm group had significantly lower scores of gross motor, fine motor, and social competence than the term group (P<0.05). At the corrected age of 6 months, the preterm group had significantly lower scores of adaptability, gross motor, and fine motor than the term group (P<0.05). At the corrected age of 12 months, the preterm group had significantly lower scores of adaptability, gross motor, and social competence than the term group (P<0.05). CONCLUSIONS: Late preterm infants have early intellectual developmental delay. It is necessary to perform neurodevelopmental monitoring for late preterm infants.

A super twin T-DNA vector that allows independent gene expression during Agrobacterium-mediated transformation.

In this study, we designed and constructed a super twin T-DNA vector (pTRIDT313-g) containing two independent T-DNA cassettes-one for the selection gene Hyg and the other for the target gene Gus-to produce marker-free transgenic lines. The resulting vector was transformed into tobacco, and polymerase chain reaction (PCR) analysis showed four types of gene combinations in the T1 and T2 generations: Gus only, Hyg only, Gus+Hyg, and untransformed lines. The intermediate region from the T-DNA of the right border of Hyg to the left border of Gus in the Hyg and Gus lines was not amplified. Genome walking confirmed that the Hyg and Gus T-DNA cassettes were independently inserted in different regions of the tobacco genome. Thus, the two T-DNA cassettes were integrated randomly as independent loci into the tobacco genome. The results of reverse transcription-PCR indicated that Hyg could normally be expressed in the roots, stems, and leaves of transgenic lines, and the resistance test showed that all Hyg transgenic lines could grow in the presence of 50mg/L hygromycin. All Gus transgenic lines showed obvious blue coloration in enzyme activity tests, indicating that the Gus gene could be normally expressed in all the lines. Therefore, the super twin T-DNA vector (pTRIDT313-g) exhibits independent integration, heredity, and normal gene function from two T-DNA cassettes. This vector could be a useful and valuable tool in the production of marker-free transgenic lines.

Structure and expression of phosphoglucan phosphatase genes of Like Sex Four1 and Like Sex Four2 in barley.

Phosphoglucan phosphatases (Like-SEX4 1 and 2; LSF1 and LSF2) were reported to play roles in starch metabolism in leaves of Arabidopsis. In this study, we identified and mapped the LSF1 and LSF2 genes in barley (HvLSF1 and HvLSF2), characterized their gene and protein structures, predicted the cis-elements of their promoters, and analysed their expression patterns. HvLSF1 and HvLSF2 were mapped on the long arm of chromosome 1H (1HL) and 5H (5HL), respectively. Our results revealed varied exon-intron structures and conserved exon-intron junctions in both LSF1 and LSF2 from a range of analysed species. Alignment of protein sequences indicated that cTP and CT domains are much less varied than the functional domains (PDZ, DPS and CBM48). LSF2 was mainly expressed in anthers of barley and rice, and in leaf of Arabidopsis. LSF1 was mainly expressed in endosperm of barley and leaf of Arabidopsis and rice. The expression of LSF1 exhibited a diurnal pattern in rice only and that of LSF2 in both rice and Arabidopsis. Of the investigated stresses, only cold stress significantly reduced expression level of LSF1 and LSF2 in barley and LSF2 in Arabidopsis at late stages of the treatments. While heat treatment significantly decreased expression levels of LSF1 at middle stage (4 h) of a treatment in Arabidopsis only. The strong relationships detected between LSF2 and starch excess4 (SEX4), glucan, water dikinases or phosphoglucan, water dikinases were identified and discussed. Taken together, these results provide information of genetic manipulation of LSF1 and LSF2, especially in monocotyledon and further elucidate their regulatory mechanism in plant development.

Structure and expression analysis of genes encoding ADP-glucose pyrophosphorylase large subunit in wheat and its relatives.

ADP-glucose pyrophosphorylase (AGP), which consists of two large subunits (AGP-L) and two small subunits (AGP-S), controls the rate-limiting step in the starch biosynthetic pathway. In this study, a full-length open reading frame (ORF) of AGP-L gene (named as Agp2) in wheat and a series of Agp2 gene sequences in wheat relatives were isolated. The coding region of Agp2 contained 15 exons and 14 introns including a full-length ORF of 1566 nucleotides, and the deduced protein contained 522 amino acids (57.8 kDa). Generally, the phylogenetic tree of Agp2 indicated that sequences from A- and D-genome donor species were most similar to each other and sequences from B-genome donor species contained more variation. Starch accumulation and Agp2 expression in wheat grains reached their peak at 21 and 15 days post anthesis (DPA), respectively.

Identification of genes bordering breakpoints of the pericentric inversions on 2B, 4B, and 5A in bread wheat (Triticum aestivum L.).

Chromosome translocation is an important driving force in shaping genomes during evolution. Detailed knowledge of chromosome translocations in a given species and its close relatives should increase the efficiency and precision of chromosome engineering in crop improvement. To identify genes flanking the breakpoints of translocations and inversions as a step toward identifying breakpoints in bread wheat, we systematically analysed genes in the Brachypodium genome against wheat survey sequences and bin-mapped ESTs (expressed sequence tags) derived from the hexaploid wheat genotype 'Chinese Spring'. In addition to those well-known translocations between group 4, 5, and 7 chromosomes, this analysis identified genes flanking the three pericentric inversions on chromosomes 2B, 4B, and 5A. However, numerous chromosomal rearrangements reported in early studies could not be confirmed. The genes flanking the breakpoints reported in this study are valuable for isolating these breakpoints.