Jasmonate-based warfare between the pathogenic intruder and host plant: who wins?

Plants and microbial pathogens often engage in a fierce war that determines their survival. Host plants have evolved sophisticated regulatory mechanisms to fine-tune defense responses to counter attacks from pathogens, while pathogens often hijack the lipid-derived phytohormone jasmonate to cause hormonal signaling imbalances for efficient infection. This review focuses on the jasmonate-based warfare between host plants and pathogenic intruders, and further discusses approaches to uncouple plant growth and defense tradeoffs in crop breeding.

Prevalence and descriptive epidemiology of Turner syndrome in the United States, 2000-2017: A report from the National Birth Defects Prevention Network.

The lack of United States population-based data on Turner syndrome limits assessments of prevalence and associated characteristics for this sex chromosome abnormality. Therefore, we collated 2000-2017 data from seven birth defects surveillance programs within the National Birth Defects Prevention Network. We estimated the prevalence of karyotype-confirmed Turner syndrome diagnosed within the first year of life. We also calculated the proportion of cases with commonly ascertained birth defects, assessed associations with maternal and infant characteristics using prevalence ratios (PR) with 95% confidence intervals (CI), and estimated survival probability. The prevalence of Turner syndrome of any pregnancy outcome was 3.2 per 10,000 female live births (95% CI = 3.0-3.3, program range: 1.0-10.4), and 1.9 for live birth and stillbirth (≥20 weeks gestation) cases (95% CI = 1.8-2.1, program range: 0.2-3.9). Prevalence was lowest among cases born to non-Hispanic Black women compared to non-Hispanic White women (PR = 0.5, 95% CI = 0.4-0.6). Coarctation of the aorta was the most common defect (11.6% of cases), and across the cohort, individuals without hypoplastic left heart had a five-year survival probability of 94.6%. The findings from this population-based study may inform surveillance practices, prenatal counseling, and diagnosis. We also identified racial and ethnic disparities in prevalence, an observation that warrants further investigation.

Post-translational modifications: emerging regulators manipulating jasmonate biosynthesis and signaling.

Jasmonate (JA) is one of the key phytohormones essential for plant development and defense processes. The core JA biosynthetic and signaling pathways have been well-characterized. Notably, post-translational modifications (PTMs), which affect the protein structures and functions, have emerged as critical mechanisms to modulate JA output at different spatiotemporal levels. Disruption of PTMs in JA biosynthesis and signaling would cause the dysfunction of vital biological processes. Here, we give an overview of the PTMs that have been identified in JA biosynthetic and signaling pathways, and provide insights into the mechanisms by which PTMs define JA responses.

The role of N-myristoylation in homeostasis of brassinosteroid signaling kinase 1.

MAIN CONCLUSION: The N-myristoylation is required for BSK1 proper plasma membrane targeting and protein turnover. Brassinosteroid (BR) signaling kinase 1 (BSK1), with a myristoylation site at its N-terminus to anchor at plasma membrane (PM), is involved in BR-regulated plant growth and flg22-triggered immunity responses. However, little is known about the role of N-myristoylation in BSK1 protein homeostasis. Here, we revealed that N-myristoylation is critical to the PM targeting and protein stability of BSK1. The N-myristoylation-deficient mutant BSK1G2A mainly distributed in the cytoplasm and retained in the endoplasmic reticulum. We further found that the BSK1G2A proteins were unstable and degraded through ATG8e-labled autophagic pathway. This study provides a new insight into the regulation of plant protein homeostasis.

Changes in Spina Bifida Lesion Level after Folic Acid Fortification in the US.

OBJECTIVE: To assess whether the severity of cases of spina bifida changed after the institution of mandatory folic acid fortification in the US. STUDY DESIGN: Six active population-based birth defects programs provided data on cases of spina bifida for 1992-1996 (prefortification period) and 1999-2016 (postfortification period). The programs contributed varying years of data. Case information included both a medical record verbatim text description of the spina bifida diagnosis and spina bifida codes (International Classification of Diseases, Clinical Modification, or a modified birth defects surveillance coding system). Comparing the prefortification and postfortification periods, aORs for case severity (upper-level lesions [cervical, thoracic] vs lower-level lesions [lumbar, sacral]) and prevalence ratios (PRs) were estimated. RESULTS: A total of 2593 cases of spina bifida (out of 7 816 062 live births) met the inclusion criteria, including 573 cases from the prefortification period and 2020 cases from the postfortification period. Case severity decreased by 70% (aOR, 0.30; 95% CI, 0.26-0.35) between the fortification periods. The decrease was most pronounced for non-Hispanic White mothers. Overall spina bifida prevalence declined by 23% (PR, 0.77; 95% CI, 0.71-0.85), with similar reductions seen across the early, mid, and recent postfortification periods. A statistically significant decrease in upper-level lesions occurred in the postfortification period compared with the prefortification period (PR, 0.28; 95% CI, 0.22-0.34), whereas the prevalence of lower-level lesions remained relatively similar (PR, 0.94; 95% CI, 0.84-1.05). CONCLUSIONS: The severity of spina bifida cases decreased after mandatory folic acid fortification in the US. Further examination is warranted to better understand the potential effect of folic acid on spina bifida severity.

Phosphorylation-Mediated Dynamics of Nitrate Transceptor NRT1.1 Regulate Auxin Flux and Nitrate Signaling in Lateral Root Growth.

The dual-affinity nitrate transceptor NITRATE TRANSPORTER1.1 (NRT1.1) has two modes of transport and signaling, governed by Thr-101 (T101) phosphorylation. NRT1.1 regulates lateral root (LR) development by modulating nitrate-dependent basipetal auxin export and nitrate-mediated signal transduction. Here, using the Arabidopsis (Arabidopsis thaliana) NRT1.1T101D phosphomimetic and NRT1.1T101A nonphosphorylatable mutants, we found that the phosphorylation state of NRT1.1 plays a key role in NRT1.1 function during LR development. Single-particle tracking revealed that phosphorylation affected NRT1.1 spatiotemporal dynamics. The phosphomimetic NRT1.1T101D form showed fast lateral mobility and membrane partitioning that facilitated auxin flux under low-nitrate conditions. By contrast, nonphosphorylatable NRT1.1T101A showed low lateral mobility and oligomerized at the plasma membrane (PM), where it induced endocytosis via the clathrin-mediated endocytosis and microdomain-mediated endocytosis pathways under high-nitrate conditions. These behaviors promoted LR development by suppressing NRT1.1-controlled auxin transport on the PM and stimulating Ca2+-ARABIDOPSIS NITRATE REGULATED1 signaling from the endosome.

Adverse Pregnancy and Neonatal Outcomes Among Marshallese Women Living in the United States.

Objective Despite heterogeneity among Pacific Islanders, most studies aggregate them regardless of origin. Thus, limited information is available about perinatal outcomes among various subgroups of Pacific Islanders in the United States, including immigrants from the Republic of the Marshall Islands. We sought to evaluate perinatal outcomes among Marshallese women. Methods We conducted a cross-sectional study of women with at least one singleton live birth between 1997 and 2013 in two Arkansas counties using birth certificate data from the Arkansas Department of Health. Unadjusted and adjusted prevalence ratios (PR) and 95% confidence intervals (CI) were calculated from modified Poisson regression models. Results Of the 91,662 singleton births in both counties during the study period, 2488 were to Marshallese women. In adjusted analyses, Marshallese women had higher prevalence of "other medical risk factors" (PR = 1.47; 95% CI 1.30, 1.65) than NH White women. Marshallese women had higher rates of precipitous labor and fetal distress during labor compared to NH White women (PR = 2.65; 95% CI 2.22, 3.17 and 1.89; 95% CI 1.62, 2.21, respectively). Marshallese were also more likely to have tocolysis (PR = 1.43; 95% CI 1.16, 1.76), forceps (PR = 1.68; 95% CI 1.16, 2.43) or vacuum (PR = 1.89; 95% CI 1.60, 2.22) used in delivery and cesarean section (PR = 1.13; 95% CI 1.01, 1.27). Marshallese infants had higher rates of anemia (PR = 3.10; 95% CI 2.01, 4.77), birth injury (PR = 2.13; 95% CI 1.50, 3.03), assisted ventilation < 30 min (PR = 2.11; 95% CI 1.64, 2.71), preterm birth (PR = 1.67; 95% CI 1.50, 1.83), and small-for-gestational age (PR = 1.25; 95% CI 1.12, 1.39) than NH White infants. Conclusions Marshallese women and infants had higher rates of adverse perinatal outcomes compared to their NH White counterparts. Additional studies are needed to determine if perinatal outcomes among the Marshallese differed from other Pacific Islander subgroups.

JA-Induced Endocytosis of AtRGS1 Is Involved in G-Protein Mediated JA Responses.

Arabidopsis heterotrimeric G proteins regulate diverse plant growth and defense processes by coupling to 7TM AtRGS1 proteins. Although G protein mutants display alterations in response to multiple plant hormones, the underlying mechanism by which G proteins participate in the regulation of hormone responses remains elusive. Here, we show that genetic disruption of Gα and Gß subunits results in reduced sensitivity to JA treatment. Furthermore, using confocal microscopy, VA-TIRFM, and FRET-FLIM, we provide evidence that stimulation by JA induces phosphorylation- and C-terminus-dependent endocytosis of AtRGS1, which then promotes dissociation of AtRGS1 from AtGPA1. In addition, SPT analysis reveals that JA treatment affects the diffusion dynamics of AtRGS1 and AtRGS1-ΔCt. Taken together, these findings suggest that the JA signal activates heterotrimeric G proteins through the endocytosis of AtRGS1 and dissociation of AtRGS1 from AtGPA1, thus providing valuable insight into the mechanisms of how the G protein system perceives and transduces phytohormone signals.

PDM3, a pentatricopeptide repeat-containing protein, affects chloroplast development.

The chloroplast, as the photosynthetic organelle of plants, plays a crucial role in plant development. Extensive studies have been conducted on chloroplast development; however, the related regulatory mechanism still remains elusive. Here, we characterized a mutant with defective chloroplasts in Arabidopsis, termed pigment-defective mutant3 (pdm3), which exhibits a distinct albino phenotype in leaves, eventually leading to pdm3 seedling lethality under autotrophic growth conditions. Electron microscopy demonstrated that the number of thylakoids was reduced and the structure of those thylakoids was disrupted in the pdm3 mutant, which eventually led to the breakdown of chloroplasts. Sequence analysis showed that PDM3 encodes a chloroplast protein consisting of 12 pentratricopeptide repeat domains that belongs to the P subgroup. Both confocal microscopic analysis and immunoblotting in the chloroplast protein fraction showed that PDM3 was located in the stroma. Furthermore, analysis of the transcript profiles of chloroplast genes revealed that plastid-encoded polymerase-dependent transcript levels were markedly reduced, while nuclear-encoded polymerase-dependent transcript levels were increased in pdm3 mutants. In addition, we found that the splicing of introns in trnA, ndhB, and clpP-1 is also affected in pdm3. Taken together, we propose that PDM3 plays an essential role in chloroplast development in Arabidopsis.

THESEUS1 positively modulates plant defense responses against Botrytis cinerea through GUANINE EXCHANGE FACTOR4 signaling.

The plant cell wall is an important interface for sensing pathogen attack and activating signaling pathways that promote plant immune responses. THESEUS1 (THE1) acts as a sensor of cell wall integrity that controls cell elongation during plant growth. However, no specific role for THE1 in plant defense responses has been reported. Here, we found that THE1 interacts with GUANINE EXCHANGE FACTOR4 (GEF4) and that both proteins play regulatory roles in plant resistance to the necrotrophic fungus Botrytis cinerea. Genetic analysis showed that THE1 and GEF4 function in the same genetic pathway to mediate plant defense responses. In addition, using transcriptome analysis, we identified various genes (such as defense-related, secondary metabolite-related, and transcription factor genes) that are likely downstream targets in the THE1-GEF4 signaling pathway. Our results suggest that THE1 functions as an upstream regulator of GEF4 signaling to positively regulate defense responses against B. cinerea in Arabidopsis.

Screening and Validation of Housekeeping Genes of the Root and Cotyledon of Cunninghamia lanceolata under Abiotic Stresses by Using Quantitative Real-Time PCR.

Cunninghamia lanceolata (Chinese fir) is a fast-growing and commercially important conifer of the Cupressaceae family. Due to the unavailability of complete genome sequences and relatively poor genetic background information of the Chinese fir, it is necessary to identify and analyze the expression levels of suitable housekeeping genes (HKGs) as internal reference for precise analysis. Based on the results of database analysis and transcriptome sequencing, we have chosen five candidate HKGs (Actin, GAPDH, EF1a, 18S rRNA, and UBQ) with conservative sequences in the Chinese fir and related species for quantitative analysis. The expression levels of these HKGs in roots and cotyledons under five different abiotic stresses in different time intervals were measured by qRT-PCR. The data were statistically analyzed using the following algorithms: NormFinder, BestKeeper, and geNorm. Finally, RankAggreg was applied to merge the sequences generated from three programs and rank these according to consensus sequences. The expression levels of these HKGs showed variable stabilities under different abiotic stresses. Among these, Actin was the most stable internal control in root, and GAPDH was the most stable housekeeping gene in cotyledon. We have also described an experimental procedure for selecting HKGs based on the de novo sequencing database of other non-model plants.

Secular trends of low birthweight and macrosomia and related maternal factors in Beijing, China: a longitudinal trend analysis.

BACKGROUND: Information tracking changes of birthweight is scarce in China. To examine trends of low birthweight (birthweight < 2500 g) and macrosomia (birthweight ≥ 4000 g) and potential risk factors in Beijing, hospital records from two major obstetrics and gynecology hospitals in urban districts in Beijing were analyzed. METHODS: Hospital records from 1996 to 2010 were retrieved. Information of prenatal examination and birth outcomes was entered into a structured database. Live births were used for trend analysis. Information of live births in 2010 was used to identify potential risk factors. RESULTS: A total of 63 661 live births were delivered during 1996-2010 in the study hospitals. The average birthweight increased from 3271 g in 1996 to 3 359 g in 2000 and slightly declined to 3 331 in 2010. The percentage of low birthweight fluctuated around 4.0%. No significant increase or decrease was observed. Preterm birth was the main cause of low birthweight, accounting for more than 73% of low birthweight. The average percentage of macrosomia was 7.6%. The percentages of macrosomia increased from 6.6% in 1996 to 9.5% in 2000 and declined to 7.0% in 2010. Excessive gestational weight gain and gestational diabetes were significantly associated with macrosomia. CONCLUSIONS: Continuously monitoring abnormal birthweight is needed and intervention should focus on appropriate gestational weight gain and reduction of preterm birth and gestational diabetes.

Hypospadias prevalence by severity and associated risk factors: A population-based active surveillance analysis.

INTRODUCTION: Hypospadias is one of the most common congenital anomalies. Trends of hypospadias prevalence by severity are not well reported. Most prevalence studies consist of pooled data from different countries or states suffer from low data quality due to inconsistent methodologies, limited variables, and lack of categorization of hypospadias severity. OBJECTIVE: The objective of this study is to examine the prevalence of hypospadias by degrees of severity and associated risk factors using combined data sources from a stable and well-defined population. STUDY DESIGN: The study population includes infants born with hypospadias to mothers residing in Arkansas from 1997 to 2016. Cases were identified from an active population-based surveillance program of birth defects. Identified hypospadias cases from surveillance data were linked to birth certificate and to a clinical database. These two data sources provide more details on the location of the defect and maternal and infant characteristics. The prevalence and 95% confidence intervals were calculated using total male live births as denominator. Chi-square test was used to assess the association of nominal variables. Logistic regression was used to calculate adjusted odds ratio. RESULTS: A total 3230 hypospadias cases were identified from 1997 to 2016. The overall prevalence is 83.0 per 10,000 male births. A majority of cases (56.7%) were classified as first degree with the others having second degree (22.8%), third degree (4.7%) or not otherwise specified (15.6%). The highest prevalence of hypospadias was observed among Non-Hispanic whites. Higher prevalence also was observed among mothers in the older age group with no prenatal care in the first trimester and with gestational hypertension or diabetes. Premature or small for gestational age infants tend to have higher prevalence across all levels of severity. The number of hypospadias cases increased over time. After maternal age, race and education were adjusted, higher risk persisted for infants of restricted fetal growth, mothers with gestational hypertension or diabetes and the cohort of 2013-2016. CONCLUSION: There is an increase of hypospadias cases in Arkansas. Several maternal and infant characteristics associated with higher prevalence for all levels of severity are worth further investigation.

VA-TIRFM-based SM kymograph analysis for dwell time and colocalization of plasma membrane protein in plant cells.

BACKGROUND: The plasma membrane (PM) proteins function in a highly dynamic state, including protein trafficking and protein homeostasis, to regulate various biological processes. The dwell time and colocalization of PM proteins are considered to be two important dynamic features determining endocytosis and protein interactions, respectively. Dwell-time and colocalization detected using traditional fluorescence microscope techniques are often misestimated due to bulk measurement. In particular, analyzing these two features of PM proteins at the single-molecule level with spatiotemporal continuity in plant cells remains greatly challenging. RESULTS: We developed a single molecular (SM) kymograph method, which is based on variable angle-total internal reflection fluorescence microscopy (VA-TIRFM) observation and single-particle (co-)tracking (SPT) analysis, to accurately analyze the dwell time and colocalization of PM proteins in a spatial and temporal manner. Furthermore, we selected two PM proteins with distinct dynamic behaviors, including AtRGS1 (Arabidopsis regulator of G protein signaling 1) and AtREM1.3 (Arabidopsis remorin 1.3), to analyze their dwell time and colocalization upon jasmonate (JA) treatment by SM kymography. First, we established new 3D (2D+t) images to view all trajectories of the interest protein by rotating these images, and then we chose the appropriate point without changing the trajectory for further analysis. Upon JA treatment, the path lines of AtRGS1-YFP appeared curved and short, while the horizontal lines of mCherry-AtREM1.3 demonstrated limited changes, indicating that JA might initiate the endocytosis of AtRGS1. Analysis of transgenic seedlings coexpressing AtRGS1-YFP/mCherry-AtREM1.3 revealed that JA induces a change in the trajectory of AtRGS1-YFP, which then merges into the kymography line of mCherry-AtREM1.3, implying that JA increases the colocalization degree between AtRGS1 and AtREM1.3 on the PM. These results illustrate that different types of PM proteins exhibit specific dynamic features in line with their corresponding functions. CONCLUSIONS: The SM-kymograph method provides new insight into quantitively analyzing the dwell time and correlation degree of PM proteins at the single-molecule level in living plant cells.

Jasmonate perception: Ligand-receptor interaction, regulation, and evolution.

Phytohormones integrate external environmental and developmental signals with internal cellular responses for plant survival and multiplication in changing surroundings. Jasmonate (JA), which might originate from prokaryotes and benefit plant terrestrial adaptation, is a vital phytohormone that regulates diverse developmental processes and defense responses against various environmental stresses. In this review, we first provide an overview of ligand-receptor binding techniques used for the characterization of phytohormone-receptor interactions, then introduce the identification of the receptor COI1 and active JA molecules, and finally summarize recent advances on the regulation of JA perception and its evolution.

Phase separation of the nuclear pore complex facilitates selective nuclear transport to regulate plant defense against pathogen and pest invasion.

The nuclear pore complex (NPC), the sole exchange channel between the nucleus and cytoplasm, is composed of several subcomplexes, among which the central barrier determines the permeability/selectivity of the NPC to dominate the nucleocytoplasmic trafficking essential for many important signaling events in yeast and mammals. How plant NPC central barrier controls selective transport is a crucial question remaining to be elucidated. In this study, we uncovered that phase separation of the central barrier is critical for the permeability and selectivity of plant NPC in the regulation of various biotic stresses. Phenotypic assays of nup62 mutants and complementary lines showed that NUP62 positively regulates plant defense against Botrytis cinerea, one of the world's most disastrous plant pathogens. Furthermore, in vivo imaging and in vitro biochemical evidence revealed that plant NPC central barrier undergoes phase separation to regulate selective nucleocytoplasmic transport of immune regulators, as exemplified by MPK3, essential for plant resistance to B. cinerea. Moreover, genetic analysis demonstrated that NPC phase separation plays an important role in plant defense against fungal and bacterial infection as well as insect attack. These findings reveal that phase separation of the NPC central barrier serves as an important mechanism to mediate nucleocytoplasmic transport of immune regulators and activate plant defense against a broad range of biotic stresses.

The role of Arabidopsis Rubisco activase in jasmonate-induced leaf senescence.

Leaf senescence, as the last stage of leaf development, is regulated by diverse developmental and environmental factors. Jasmonates (JAs) have been shown to induce leaf senescence in several plant species; however, the molecular mechanism for JA-induced leaf senescence remains unknown. In this study, proteomic, genetic, and physiological approaches were used to reveal the molecular basis of JA-induced leaf senescence in Arabidopsis (Arabidopsis thaliana). We identified 35 coronatine-insensitive 1 (COI1)-dependent JA-regulated proteins using two-dimensional difference gel electrophoresis in Arabidopsis. Among these 35 proteins, Rubisco activase (RCA) was a COI1-dependent JA-repressed protein. We found that RCA was down-regulated at the levels of transcript and protein abundance by JA in a COI1-dependent manner. We further found that loss of RCA led to typical senescence-associated features and that the COI1-dependent JA repression of RCA played an important role in JA-induced leaf senescence.

Prevalence of critical congenital heart defects and selected co-occurring congenital anomalies, 2014-2018: A U.S. population-based study.

BACKGROUND: Critical congenital heart defects (CCHDs) are one of the most common types of birth defects and can lead to significant morbidity and mortality along with surgical or catheter interventions within the first year of life. This report updates previously published estimates of CCHD prevalence with the latest population-based surveillance data from 19 birth defect surveillance programs. METHODS: The U.S. population-based surveillance programs submitted data on identified cases of 12 CCHDs and co-occurring cardiovascular and chromosomal birth defects from 2014 to 2018. We estimated prevalence by program type and maternal and infant characteristics. Among nine programs with active case ascertainment that collect more than live births, we estimated the percentage of co-occurring cardiovascular and chromosomal birth defects for the 12 CCHDs. RESULTS: We identified 18,587 cases of CCHD among all participating programs. Overall CCHD prevalence was 19.6 per 10,000 live births among all 19 programs and 20.2 per 10,000 live births among active programs. Among maternal racial/ethnic groups, infants/fetuses born to American Indian/Alaska Native mothers showed the highest overall prevalence for all CCHDs (28.3 per 10,000) along with eight of the 12 individual CCHDs. Among 7,726 infants/fetuses with CCHD from active case ascertainment programs, 15.8% had at least one co-occurring chromosomal birth defect. CONCLUSION: Our study provides prevalence estimates for CCHDs by maternal and infant characteristics along with co-occurrence with cardiovascular and chromosomal birth defects among infants/fetuses with CCHD using one of the largest and most recent cohorts since the implementation of widespread CCHD screening. These data can provide a basis for future research to better understand risk factors for these defects.

Current progress of PM-localized protein functions in jasmonate pathway.

Jasmonate (JA), a class of lipid-derived phytohormone, regulates diverse developmental processes and responses to abiotic or biotic stresses. The biosynthesis and signaling of JA mainly occur in various organelles, except for the plasma membrane (PM). Recently, several PM proteins have been reported to be associated with the JA pathway. This mini-review summarized the recent progress on the functional role of PM-localized proteins involved in JA transportation, JA-related defense responses, and JA-regulated endocytosis.