SNF1-RELATED PROTEIN KINASES 2 (SnRK2) are important components of early osmotic and salt stress signaling pathways in plants. The Arabidopsis (
) SnRK2 family comprises the abscisic acid ...(ABA)-activated protein kinases SnRK2.2, SnRK2.3, SnRK2.6, SnRK2.7, and SnRK2.8, and the ABA-independent subclass 1 protein kinases SnRK2.1, SnRK2.4, SnRK2.5, SnRK2.9, and SnRK2.10. ABA-independent SnRK2s act at the posttranscriptional level via phosphorylation of VARICOSE (VCS), a member of the mRNA decapping complex, that catalyzes the first step of 5'mRNA decay. Here, we identified VCS and VARICOSE RELATED (VCR) as interactors and phosphorylation targets of SnRK2.5, SnRK2.6, and SnRK2.10. All three protein kinases phosphorylated Ser-645 and Ser-1156 of VCS, whereas SnRK2.6 and SnRK2.10 also phosphorylated VCS Ser-692 and Ser-680 of VCR. We showed that subclass 1 SnRK2s, VCS, and 5' EXORIBONUCLEASE 4 (XRN4) are involved in regulating root growth under control conditions as well as modulating root system architecture in response to salt stress. Our results suggest interesting patterns of redundancy within subclass 1 SnRK2 protein kinases, with SnRK2.1, SnRK2.5, and SnRK2.9 controlling root growth under nonstress conditions and SnRK2.4 and SnRK2.10 acting mostly in response to salinity. We propose that subclass 1 SnRK2s function in root development under salt stress by affecting the transcript levels of aquaporins, as well as CYP79B2, an enzyme involved in auxin biosynthesis.
Salinity stress constrains lateral root (LR) growth and severely affects plant growth. Auxin signaling regulates LR formation, but the molecular mechanism by which salinity affects root auxin ...signaling and whether salt induces other pathways that regulate LR development remains unknown. In Arabidopsis thaliana, the auxin-regulated transcription factor LATERAL ORGAN BOUNDARY DOMAIN 16 (LBD16) is an essential player in LR development under control conditions. Here, we show that under high-salt conditions, an alternative pathway regulates LBD16 expression. Salt represses auxin signaling but, in parallel, activates ZINC FINGER OF ARABIDOPSIS THALIANA 6 (ZAT6), a transcriptional activator of LBD16. ZAT6 activates LBD16 expression, thus contributing to downstream cell wall remodeling and promoting LR development under high-salt conditions. Our study thus shows that the integration of auxin-dependent repressive and salt-activated auxin-independent pathways converging on LBD16 modulates root branching under high-salt conditions.
Endocytosis and relocalization of auxin carriers represent important mechanisms for adaptive plant growth and developmental responses. Both root gravitropism and halotropism have been shown to be ...dependent on relocalization of auxin transporters. Following their homology to mammalian phospholipase Ds (PLDs), plant PLDζ‐type enzymes are likely candidates to regulate auxin carrier endocytosis. We investigated root tropic responses for an Arabidopsis pldζ1‐KO mutant and its effect on the dynamics of two auxin transporters during salt stress, that is, PIN2 and AUX1. We found altered root growth and halotropic and gravitropic responses in the absence of PLDζ1 and report a role for PLDζ1 in the polar localization of PIN2. Additionally, irrespective of the genetic background, salt stress induced changes in AUX1 polarity. Utilizing our previous computational model, we found that these novel salt‐induced AUX1 changes contribute to halotropic auxin asymmetry. We also report the formation of “osmotic stress‐induced membrane structures.” These large membrane structures are formed at the plasma membrane shortly after NaCl or sorbitol treatment and have a prolonged presence in a pldζ1 mutant. Taken together, these results show a crucial role for PLDζ1 in both ionic and osmotic stress‐induced auxin carrier dynamics during salt stress.
This work shows that both ionic and osmotic stress affect auxin carrier dynamics during salinity stress, a response that requires the action of the phospholipase PLDζ1. Mathematical modelling shows that impaired cellular polarity in roots of pldζ1 seedlings explains their different halotropism (salt avoidance) response.
A central tenet of caring for patients with ARDS is to treat the underlying cause, be it sepsis, pneumonia, or removal of an offending toxin. Identifying the risk factor for ARDS has even been ...proposed as essential to diagnosing ARDS. Not infrequently, however, the precipitant for acute hypoxemic respiratory failure is unclear, and this raises the question of whether a histologic lung diagnosis would benefit the patient. In this review, we consider the historic role of pathology in establishing a diagnosis of ARDS and the published experience of surgical and transbronchial lung biopsy in patients with ARDS. We reflect on which pathologic diagnoses influence treatment and suggest a patient-centric approach to weigh the risks and benefits of a lung biopsy for critically ill patients who may have ARDS.
Reducing food loss and waste (FLW) is widely recognized as an important lever for lowering the environmental impacts of food systems. The United Nations Sustainable Development Agenda includes a goal ...to reduce FLW by 50% by 2030. Given differences in resource inputs along the food supply chain (FSC), the environmental benefits of FLW reduction will vary by stage of the FSC. Here, we identify the points along the supply chain where a 50% FLW reduction could yield the largest potential environmental benefits, assuming that decreases in consumption propagate back up the supply chain to reduce production. We use an environmentally extended input-output (EEIO) model combined with data on rates of FLW to calculate the scale of the total environmental impacts of the U.S. food system resulting from lost or wasted food. We evaluate the maximum potential environmental benefit resulting from 50% FLW reduction at all possible combinations of six supply chain stages (agricultural production, food processing, distribution/retail, restaurant foodservice, institutional foodservice, and households).
We find that FLW reduction efforts should target the foodservice (restaurant) sector, food processing sector, and household consumption. Halving FLW in the foodservice sector has the highest potential to reduce greenhouse gas output and energy use. Halving FLW in the food processing sector could reduce the most land use and eutrophication potential, and reducing household consumption waste could avert the most water consumption. In contrast, FLW reduction at the retail, institutional foodservice, and farm level averts less environmental impact. Our findings may help determine optimal investment in FLW reduction strategies.
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•Much of the U.S.'s environmental burden is due to food loss and waste (FLW).•The United Nations has called for 50% FLW reduction worldwide by 2030 (SDG 12.3).•We used an EEIO model to explore environmental consequences of FLW reduction.•Halving FLW could reduce the environmental impact of the U.S. food system by 8–10%.•FLW policy and practice should target foodservice, food processing, and households.
Freezing limits plant growth and crop productivity, and plant species in temperate zones have the capacity to develop freezing tolerance through complex modulation of gene expression affecting ...various aspects of metabolism and physiology. While many components of freezing tolerance have been identified in model species under controlled laboratory conditions, little is known about the mechanisms that impart freezing tolerance in natural populations of wild species. Here, we performed a quantitative trait locus (QTL) study of acclimated freezing tolerance in seedlings of Boechera stricta, a highly adapted relative of Arabidopsis (Arabidopsis thaliana) native to the Rocky Mountains. A single QTL was identified that contained the gene encoding ACYL-COENZYME A:DIACYLGLYCEROL ACYLTRANSFERASE1 (BstDGAT1), whose expression is highly cold responsive. The primary metabolic enzyme DGAT1 catalyzes the final step in assembly of triacylglycerol (TAG) by acyl transfer from acyl-CoA to diacylglycerol. Freezing tolerant plants showed higher DGAT1 expression during cold acclimation than more sensitive plants, and this resulted in increased accumulation of TAG in response to subsequent freezing. Levels of oligogalactolipids that are produced by SFR2 (SENSITIVE TO FREEZING2), an indispensable element of freezing tolerance in Arabidopsis, were also higher in freezing-tolerant plants. Furthermore, overexpression of AtDGAT1 led to increased freezing tolerance. We propose that DGAT1 confers freezing tolerance in plants by supporting SFR2-mediated remodeling of chloroplast membranes.
Purpose
A causal biomarker for acute respiratory distress syndrome (ARDS) could fuel precision therapy options. Plasma angiopoietin-2 (ANG2), a vascular permeability marker, is a strong candidate on ...the basis of experimental and observational evidence. We used genetic causal inference methods—Mendelian randomization and mediation—to infer potential effects of plasma ANG2.
Methods
We genotyped 703 septic subjects, measured ICU admission plasma ANG2, and performed a quantitative trait loci (QTL) analysis to determine variants in the
ANGPT2
gene associated with plasma ANG2 (
p
< 0.005). We then used linear regression and post-estimation analysis to genetically predict plasma ANG2 and tested genetically predicted ANG2 for ARDS association using logistic regression. We estimated the proportion of the genetic effect explained by plasma ANG2 using mediation analysis.
Results
Plasma ANG2 was strongly associated with ARDS (OR 1.59 (95% CI 1.35, 1.88) per log). Five
ANGPT2
variants were associated with ANG2 in European ancestry subjects (
n
= 404). Rs2442608C, the most extreme
cis
QTL (coefficient 0.22, 95% CI 0.09–0.36,
p
= 0.001), was associated with higher ARDS risk: adjusted OR 1.38 (95% CI 1.01, 1.87)
, p
= 0.042. No significant QTL were identified in African ancestry subjects. Genetically predicted plasma ANG2 was associated with ARDS risk: adjusted OR 2.25 (95% CI 1.06–4.78),
p
= 0.035. Plasma ANG2 mediated 34% of the rs2442608C-related ARDS risk.
Conclusions
In septic European ancestry subjects, the strongest ANG2-determining
ANGPT2
genetic variant is associated with higher ARDS risk. Plasma ANG2 may be a causal factor in ARDS development. Strategies to reduce plasma ANG2 warrant testing to prevent or treat sepsis-associated ARDS.
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