Molecular characterization and functional analysis of plant WRKY genes

WRKY genes are widely distributed in higher plants, and constitute one of the largest transcription factor families. Over recent decades, molecular characterization and functional analysis of WRKY have been extensively studied and reported to be involved in many physiological and biochemical processes. This review describes the current knowledge about their molecular, structural and functional characteristics, including the alternative splicing, the response to biotic and abiotic stress, the senescence, the morphological architecture and the evolution. It shows that WRKY transcription factors play a crucial role in plants’ developmental and physiological processes. Furthermore, the group-I WRKY genes may represent the ancestral form and the WRKY genes not only limited in the plant kingdom.Keywords: WRKY, structure characteristic, biotic and abiotic stress, senescence, development, evolutio

Genetic analysis and assessment of stay-green traits in hybrids of temperate and tropical maize germplasm

Leaf stay-green is a trait in which plants retain leaves with green tissue from flowering through physiological ma¬turity in maize. To assess whether this characteristic improved grain filling in maize, we analyzed five stay-green traits, five grain yield-related traits, and three photosynthetic parameters in 10 hybrids derived from an incomplete diallele cross mating design between five temperate and two tropical maize germplasm inbred lines. The hybrids were grown in three different environments. The degree of stay-green (DSG) was significantly positively correlated with grain yield, ear length, number of grains per row, number of visible green leaves at maturity (MNL), ratio of visible source leaves (RSL), and photosynthetic potential at maturity (MPP). The highest correlation between traits was between RSL and MNL. All five stay-green traits were significantly positively correlated with net photosyn¬thetic rate (Pn). RSL had the highest broad-sense heritability among the stay-green traits evaluated. Our findings suggest that RSL is an important stay-green trait and can be used as a selection criterion for improving stay-green traits in maize breeding programs

Effects of Low-Level Autonomic Stimulation on Prevention of Atrial Fibrillation Induced by Acute Electrical Remodeling

Background. Rapid atrial pacing (RAP) can induce electrical and autonomic remodeling and facilitate atrial fibrillation (AF). Recent reports showed that low-level vagosympathetic nerve stimulation (LLVNS) can suppress AF, as an antiarrhythmic effect. We hypothesized that LLVNS can reverse substrate heterogeneity induced by RAP. Methods and Results. Mongrel dogs were divided into (LLVNS+RAP) and RAP groups. Electrode catheters were sutured to multiple atrial sites, and LLVNS was applied to cervical vagosympathetic trunks with voltage 50% below the threshold slowing sinus rate by ⩽30 msec. RAP induced a significant decrease in effective refractory period (ERP) and increase in the window of vulnerability at all sites, characterized by descending and elevated gradient differences towards the ganglionic plexi (GP) sites, respectively. The ERP dispersion was obviously enlarged by RAP and more significant when the ERP of GP-related sites was considered. Recovery time from AF was also prolonged significantly as a result of RAP. LLVNS could reverse all these changes induced by RAP and recover the heterogeneous substrate to baseline. Conclusions. LLVNS can reverse the electrical and autonomic remodeling and abolish the GP-central gradient differences induced by RAP, and thus it can recover the homogeneous substrate, which may be the underlying mechanism of its antiarrhythmic effect

The Structure, Function, and Regulation of Starch Synthesis Enzymes SSIII with Emphasis on Maize

Starch biosynthesis is a complex and highly controlled process that requires coordinated activities among multiple enzymes. Starch synthase III (SSIII) is the largest protein in the starch synthase complex and its function is to lengthen long-chain amylopectin in starch synthesis. It potentially affects the activity of other key enzymes in starch synthesis through protein–protein interactions; therefore, its function and regulation play a predominant role in starch synthesis. In this review, we summarized the main research of SSIII including its biochemical characteristics, structural features, expression atlas, and regulation means. Structural features and expressional analysis indicated that SSIIIa is the main functional protein in maize endosperm rather than SSIIIb-a and SSIIIb-b, even though they are similar in the tertiary structures. The regulation investigation of SSIIIa showed that there are 13 transcription factors that control the transcription of SSIIIa. Interaction network analysis showed that SSIIIa could be involved with ten other key enzymes in starch synthesis. In conclusion, this review considerably extends our understanding of SSIII and provides the theoretical basis for improving starch synthesis by SSIII in maize

<i>DEK219</i> and <i>HSF17</i> Collaboratively Regulate the Kernel Length in Maize

The kernel length is a crucial determinant of maize (Zea mays L.) yield; however, only a limited number of genes regulating kernel length have been validated, thus leaving our understanding of the mechanisms governing kernel length incomplete. We previously identified a maize kernel mutant, defective kernel219 (dek219), which encodes the DICER-LIKE1 protein that is essential for miRNA biogenesis. The present study revealed that dek219 consistently exhibits a stable phenotype characterized by a reduced kernel length. Further analysis indicated that dek219 may reduce the kernel length by inhibiting the expression of genes involved in regulating kernel length. By employing miRNA-target gene prediction, expression analysis, and correlation analysis, we successfully identified nine transcription factors that potentially participate in the regulation of kernel length under the control of DEK219. Among them, the upregulation fold change of HEAT SHOCK TRANSCRIPTION FACTOR17 (HSF17) expression was the highest, and the difference was most significant. The results of transient expression analysis and electrophoretic mobility shift assay (EMSA) indicated that HSF17 can inhibit the expression of DEFECTIVE ENDOSPERM18 (DE18), a gene involved in regulating kernel length. Furthermore, the hsf17 mutant exhibited a significant increase in kernel length, suggesting that HSF17 functions as a negative regulator of kernel length. The results of this study provide crucial evidence for further elucidating the molecular regulatory mechanism underlying maize kernel length and also offer valuable genetic resources for breeding high-yielding maize varieties

Genome-Wide Association Study Identifies Quantitative Trait Loci and Candidate Genes Involved in Deep-Sowing Tolerance in Maize (<i>Zea mays</i> L.)

Deep sowing is an efficient strategy for maize to ensure the seedling emergence rate under adverse conditions such as drought or low temperatures. However, the genetic basis of deep-sowing tolerance-related traits in maize remains largely unknown. In this study, we performed a genome-wide association study on traits related to deep-sowing tolerance, including mesocotyl length (ML), coleoptile length (CL), plumule length (PL), shoot length (SL), and primary root length (PRL), using 255 maize inbred lines grown in three different environments. We identified 23, 6, 4, and 4 quantitative trait loci (QTLs) associated with ML, CL, PL, and SL, respectively. By analyzing candidate genes within these QTLs, we found a γ-tubulin-containing complex protein, ZmGCP2, which was significantly associated with ML, PL, and SL. Loss of function of ZmGCP2 resulted in decreased PL, possibly by affecting the cell elongation, thus affecting SL. Additionally, we identified superior haplotypes and allelic variations of ZmGCP2 with a longer PL and SL, which may be useful for breeding varieties with deep-sowing tolerance to improve maize cultivation

Group B streptococcal colonization in mothers and infants in western China: prevalences and risk factors

Abstract Background The epidemiology of maternal and infant Group B streptococcus (GBS) colonization is poorly understood in China. The aim of this study is to explore the prevalence and risk factors associated with maternal and infant GBS colonization in Western China. Methods From January 2017 to June 2017, a prospective study was conducted to estimate the maternal and infant GBS colonization rate by maternal rectovaginal and infant nasopharynx, ear canal and umbilical swab culture. Patient demographics, clinical characteristics and outcomes were collected. Chi-square and logistic regression analyses were used to examine the risk factors associated with GBS colonization of mothers and infants. Results The GBS colonization rate in mothers and infants was 6.1 and 0.7%, respectively. The vertical transmission rate was 7.6%. The early onset GBS infection rate was 0.58 per 1000 live births and mortality was 0.29 per 1000 live births. Age younger than 40 years (p = 0.040) and minority ethnic status (p = 0.049) were associated with higher GBS colonization rate in pregnant women. Positive GBS status in the mother prior to delivery (p < 0.001) as well as longer duration of membrane rupture (≥12 h) (p < 0.001) and longer labor (≥4 h) (p < 0.001) were all significant risk factors for GBS colonization in infants. Compared to infants without GBS colonization, infants colonized with GBS were more likely to have had a temperature of ≥38 °C (p < 0.001), developed early onset infection (EOD) (p < 0.001), and been prescribed antibiotics (p < 0.001). Furthermore, infants with GBS were more likely to have been admitted to neonatal intensive unit (NICU) (p < 0.001) with a longer hospital length of stay (LOS) (p < 0.001). Conclusions Maternal GBS colonization, longer duration of membrane rupture and labor were all major risk factors associated with GBS colonization in Chinese infants. Infant GBS colonization was associated with increased risk of EOD and NICU admission as well as longer LOS

Gibberellin induced transcription factor bZIP53 regulates CesA1 expression in maize kernels.

Proper development of the maize kernel is of great significance for high and stable maize yield to ensure national food security. Gibberellin (GA), one of the hormones regulating plant growth, is involved in modulating the development of maize kernels. Cellulose, one of the main components of plant cells, is also regulated by gibberellin. The mechanism of hormone regulation during maize grain development is highly complicated, and reports on GA-mediated modulation of cellulose synthesis during maize grain development are rare. Our study revealed that during grain growth and development, the grain length and bulk density of GA-treated corn kernels improved significantly, and the cellulose content of grains increased, while seed coat thickness decreased. The transcription factor basic region/leucine zipper motif 53 (bZIP53), which is strongly correlated with cellulose synthase gene 1 (CesA1) expression, was screened by transcriptome sequencing and the expression of the cellulose synthase gene in maize grain development after GA treatment was determined. It was found that bZIP53 expression significantly promoted the expression of CesA1. Further, analysis of the transcription factor bZIP53 determined that the gene-encoded protein was localized in the cell and nuclear membranes, but the transcription factor bZIP53 itself showed no transcriptional activation. Further studies are required to explore the interaction of bZIP53 with CesA1