BackgroundPhosphate (Pi) and Nitrogen (N) are essential macronutrients required for plant growth and development. In Arabidopsis thaliana (Arabidopsis), the transcription factor PHR1 acts as a Pi central regulator. PHL1 is a homolog of PHR1 and also plays a role in maintaining Pi homeostasis. In rice (Oryza sativa), OsPHR1–4 are the orthologs of PHR1 and have been implicated in regulating sensing and signaling cascades governing Pi homeostasis.ResultsHere the role of OsPHR3 was examined in regulating the homeostasis of N under different Pi regimes. Deficiencies of different variants of N exerted attenuating effects on the relative expression levels of OsPHR3 in a tissue-specific manner. For the functional characterization of OsPHR3, its Tos17 insertion homozygous mutants i.e., osphr3–1, osphr3–2, and osphr3–3 were compared with the wild-type for various morphophysiological and molecular traits during vegetative (hydroponics with different regimes of N variants) and reproductive (pot soil) growth phases. During vegetative growth phase, compared with the wild-type, OsPHR3 mutants showed significant variations in the adventitious root development, influx rates of 15N-NO3− and 15N-NH4+, concentrations of total N, NO3− and NH4+ in different tissues, and the relative expression levels of OsNRT1.1a, OsNRT2.4, OsAMT1;1, OsNia1 and OsNia2. The effects of the mutation in OsPHR3 was also explicit on the seed-set and grain yield during growth in a pot soil. Although Pi deficiency affected total N and NO3− concentration, the lateral root development and the relative expression levels of some of the NO3− and NH4+ transporter genes, its availability did not exert any notable regulatory influences on the traits governing N homeostasis.ConclusionsOsPHR3 plays a pivotal role in regulating the homeostasis of N independent of Pi availability.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1462-7) contains supplementary material, which is available to authorized users.

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Background: Since initially detected in late December 2019, the novel coronavirus disease 2019 (COVID-19) outbreak rapidly swept the world, which has profoundly affected healthcare system and clinical practice in the management of gastrointestinal diseases. Objectives: We aimed to evaluate the impact of COVID-19 pandemic on the pattern of hospital admissions and healthcare services for acute pancreatitis (AP). Design: We conducted a retrospective observational cohort study using the anonymized electronic medical records. Methods: This single-center, retrospective observational study from a regional medical center in the northeast of China included all consecutively admitted patients with AP from 23 January to 10 June 2020 (during the COVID-19 outbreak in Harbin), compared with the equivalent period of the previous year, in terms of demographics, clinical characteristics, and in-hospital outcomes. Results: In this article, we observed a reduction in AP admissions after the beginning of COVID-19 outbreak. With the prolonged time from symptom onset to hospitalization [32.0 (22.0–72.0) versus 18.0 (12.0–24.0) h; p < 0.001], a higher proportion of AP patients developed acute renal failure (14.0% versus 7.4%, p = 0.004) and acute necrotic collection (16.5% versus 11.2%; p = 0.038) in the COVID-19 era. The percentage of alcohol etiology significantly decreased after the implementation of social restriction measures (11.5% versus 20.4%; p = 0.002), whereas biliary etiology was numerically more common amidst the COVID-19 era (41.6% versus 32.6%; p = 0.014). No significant differences were found in the rates of intensive care unit admission and mortality between the two groups. Conclusion: This study preliminarily demonstrated the descending trend and delay in hospital presentations for AP during the outbreak of COVID-19. Given that the pandemic may persist for several years, adjustments of medical services according to the varying degrees of local breakouts are imperative to provide appropriate care for AP patients and diminish the risk of viral transmission. Registration: ClincialTrials.gov number ChiCTR2100043350.

OsSIZ1, a small ubiquitin-related modifier (SUMO) E3 ligase, exerts regulatory influences on the developmental responses and phosphate (Pi) homeostasis in rice (Oryza sativa). Whether paralogs OsSIZ1 and OsSIZ2 are functionally redundant or the latter regulates these traits independent of the former is not known. To determine this, in this study, OsSIZ2 was functionally characterized by employing reverse genetic approaches. Although the relative expression of OsSIZ2 was spatiotemporally regulated, it showed constitutive expression in root and leaf blade irrespective of Pi regime. Analysis of T-DNA insertion knockout (ossiz2) and RNAi-mediated knockdown (Ri1-3) mutants revealed positive influences on growth and developmental responses including yield-related traits. On the contrary, these mutants exhibited negative effects on the concentrations of Pi and total P in different tissues. The relative expression levels of some of the genes that are involved in Pi sensing and signaling cascades were differentially modulated in the mutants. Further, attenuation in the expression levels of OsSIZ2 in the roots of ossiz1 and relatively similar trend of the effects of the mutation in OsSIZ1 and OsSIZ2 on growth and development and total P concentration in different tissues suggested a prevalence of partial functional redundancy between these paralogs.