Effects of Soil Sterilization on the Formation and Function of Two Strains of Pisolithus Tinctorius on Eucalyptus Urophylla*)

To examine the effects of soil microbial population on mycorrhizal development and function, Eucalyptus urophylla seedlings were inoculated with two Pisolithus tinctorius isolates and grown in sterile, partly sterile and non-sterile soil. The two isolates of Pisolithus were an effective isolate (H445) collected from under eucalypts in Australia and an isolate (H615) collected from under eucalypts in the Philippines. Soils used were infertile acid soils collected from field sites in Pangasinan, Luzon and Surigao, Mindanao. In both soils, the Australian Pisolithus H445 improved the growth of E. urophylla seedlings more than Philippine isolate H615. The uninoculated seedlings exhibited stunted growth typical of P deficiency. Height at 8 weeks was significantly taller in sterile than in non-sterile soil. A significant interaction effect of inoculation and soil sterilization on height at harvest was observed only in Surigao soil. Soil sterilization had a varied effect on mycorrhizal formation. In Pangasinan soil, root colonization by H445 was significantly greater in non-sterile soil than in sterile soil. Whereas in Surigao soil, root colonization was significantly reduced by 54% from partly sterile to non-sterile soil. On the other hand, H615 showed significant mycorrhizal colonization in non-sterile soil compared from those in partly sterile and sterile soils. The degree of infection did not necessarily correspond to growth promotion in E. urophylla seedlings. These results indicate that the performance of the H445 was markedly affected by the microbial flora of the two soils. Thus, its potential use in the Philippines needs to be thoroughly tested in the field before its widespread use in any inoculation program

EFFECTS OF SOIL STERILIZATION ON THE FORMATION AND FUNCTION OF TWO STRAINS OF PISOLITHUS TINCTORIUS ON EUCALYPTUS UROPHYLLA*)

To  examine  the  effects  of  soil  microbial  population  on  mycorrhizal  development  and  function, Eucalyptus urophylla seedlings were inoculated with two Pisolithus tinctorius isolates and grown in sterile, partly sterile and non-sterile soil. The two isolates of Pisolithus were an effective isolate (H445) collected from under eucalypts in Australia and an isolate (H615) collected  from under eucalypts in the Philippines. Soils used were infertile acid soils collected from field sites in Pangasinan, Luzon and Surigao, Mindanao. In both soils, the Australian Pisolithus H445 improved the growth of E. urophylla seedlings more  than Philippine isolate H615. The uninoculated seedlings exhibited stunted growth typical of P deficiency. Height at 8 weeks was significantly taller in sterile than in non-sterile soil. A significant interaction effect of inoculation and soil sterilization on height at harvest was observed only in Surigao soil. Soil sterilization had a varied effect on mycorrhizal formation. In Pangasinan soil, root colonization by H445 was significantly greater in non-sterile soil than in sterile soil. Whereas in Surigao soil, root colonization was significantly reduced by 54% from partly sterile to non-sterile soil. On the other hand, H615 showed significant mycorrhizal colonization in non-sterile soil compared from those in partly sterile and sterile soils. The degree of infection did not necessarily correspond to growth promotion in E. urophylla seedlings. These results indicate that the performance of the H445 was markedly affected by the microbial flora of the two soils. Thus, its potential use in the Philippines needs to be thoroughly tested in the  field before its widespread use in any inoculation program.Key words: Pisolithus tinctorius/Laccaria fraterna/Pinus patula/Inoculum/Seedlings/Growth

Working with Mycorrhizas in Forestry and Agriculture

Crop Production/Industries,

Plants for planting ; indirect evidence for the movement of a serious forest pathogen, Teratosphaeria destructans, in Asia

Fungal diseases caused by native pathogens and pathogens introduced with planting stock have a significant impact on exotic plantation forestry in the tropics. Teratosphaeria destructans (formerly Kirramyces destructans) is a serious pathogen causing leaf, bud and shoot blight diseases of Eucalyptus spp. in plantations in the sub-tropics and tropics of south-east Asia. This pathogen was first discovered in Indonesia in 1995 and has subsequently spread to Thailand, China, Vietnam and East Timor. The biology, ecology and genetics of this important pathogen have not been explored yet. The objective of this study was, thus, to determine the genetic diversity and movement of T. destructans throughout south-east Asia using multi-gene phylogenies and microsatellite markers. Out of nine gene regions only two microsatellite markers detected a very low nucleotide polymorphism between isolates; seven other gene regions, ITS, β-tubulin, EF1-α, CHS, ATP6 and two microsatellite loci, reflected genetic uniformity. The two polymorphic molecular markers resolved six haplotypes among isolates from Indonesia and only a single haplotype elsewhere in Asia. The low diversity observed among isolates in the region of the first outbreak is as expected for a small founder population. The spread of a single clone over large distances throughout the region supports the hypothesis of spread via the human-mediated movement of germplasm.Murdoch University Doctoral Research Scholarship, University of Pretoria

Multiorgan MRI findings after hospitalisation with COVID-19 in the UK (C-MORE): a prospective, multicentre, observational cohort study

Introduction: The multiorgan impact of moderate to severe coronavirus infections in the post-acute phase is still poorly understood. We aimed to evaluate the excess burden of multiorgan abnormalities after hospitalisation with COVID-19, evaluate their determinants, and explore associations with patient-related outcome measures. Methods: In a prospective, UK-wide, multicentre MRI follow-up study (C-MORE), adults (aged ≥18 years) discharged from hospital following COVID-19 who were included in Tier 2 of the Post-hospitalisation COVID-19 study (PHOSP-COVID) and contemporary controls with no evidence of previous COVID-19 (SARS-CoV-2 nucleocapsid antibody negative) underwent multiorgan MRI (lungs, heart, brain, liver, and kidneys) with quantitative and qualitative assessment of images and clinical adjudication when relevant. Individuals with end-stage renal failure or contraindications to MRI were excluded. Participants also underwent detailed recording of symptoms, and physiological and biochemical tests. The primary outcome was the excess burden of multiorgan abnormalities (two or more organs) relative to controls, with further adjustments for potential confounders. The C-MORE study is ongoing and is registered with ClinicalTrials.gov, NCT04510025. Findings: Of 2710 participants in Tier 2 of PHOSP-COVID, 531 were recruited across 13 UK-wide C-MORE sites. After exclusions, 259 C-MORE patients (mean age 57 years [SD 12]; 158 [61%] male and 101 [39%] female) who were discharged from hospital with PCR-confirmed or clinically diagnosed COVID-19 between March 1, 2020, and Nov 1, 2021, and 52 non-COVID-19 controls from the community (mean age 49 years [SD 14]; 30 [58%] male and 22 [42%] female) were included in the analysis. Patients were assessed at a median of 5·0 months (IQR 4·2–6·3) after hospital discharge. Compared with non-COVID-19 controls, patients were older, living with more obesity, and had more comorbidities. Multiorgan abnormalities on MRI were more frequent in patients than in controls (157 [61%] of 259 vs 14 [27%] of 52; p<0·0001) and independently associated with COVID-19 status (odds ratio [OR] 2·9 [95% CI 1·5–5·8]; padjusted=0·0023) after adjusting for relevant confounders. Compared with controls, patients were more likely to have MRI evidence of lung abnormalities (p=0·0001; parenchymal abnormalities), brain abnormalities (p<0·0001; more white matter hyperintensities and regional brain volume reduction), and kidney abnormalities (p=0·014; lower medullary T1 and loss of corticomedullary differentiation), whereas cardiac and liver MRI abnormalities were similar between patients and controls. Patients with multiorgan abnormalities were older (difference in mean age 7 years [95% CI 4–10]; mean age of 59·8 years [SD 11·7] with multiorgan abnormalities vs mean age of 52·8 years [11·9] without multiorgan abnormalities; p<0·0001), more likely to have three or more comorbidities (OR 2·47 [1·32–4·82]; padjusted=0·0059), and more likely to have a more severe acute infection (acute CRP >5mg/L, OR 3·55 [1·23–11·88]; padjusted=0·025) than those without multiorgan abnormalities. Presence of lung MRI abnormalities was associated with a two-fold higher risk of chest tightness, and multiorgan MRI abnormalities were associated with severe and very severe persistent physical and mental health impairment (PHOSP-COVID symptom clusters) after hospitalisation. Interpretation: After hospitalisation for COVID-19, people are at risk of multiorgan abnormalities in the medium term. Our findings emphasise the need for proactive multidisciplinary care pathways, with the potential for imaging to guide surveillance frequency and therapeutic stratification

Physiological responses of plants to low boron

This review focuses on physiological responses in higher plants to B deficiency at the whole plant and organ level. Plants respond to decreasing B supply in soil solutions by slowing down or ceasing growth. Boron deficiency inhibits root elongation through limiting cell enlargement and cell division in the growing zone of root tips. In the case of severe B deficiency, the root cap, quiescent centre and protoderm of root tips disappear and root growth ceases, leading to the death of root tips. Although vascular bundles are weakly developed in B-deficient roots, early effects of B deficiency on their initiation and differentiation is poorly understood. Inhibited leaf expansion by low B indirectly decreases the photosynthetic capacity of plants, though exact roles of B in photosynthesis remain to be explored. The early inhibition of root growth, compared to shoot growth, increases the shoot:root ratio. It is hypothesised that this may enhance the susceptibility of plants to environmental stresses such as marginally deficient supplies of other nutrients and water deficit in soil. In the field, sexual reproduction is often more sensitive to low soil B than vegetative growth, and marked seed yield reductions can occur without symptoms being expressed during prior vegetative growth. In flowers, low B reduces male fertility primarily by impairing microsporogenesis and pollen tube growth. Post-fertilisation effects include impaired embryogenesis, resulting in seed abortion or the formation of incomplete or damaged embryos, and malformed fruit. However, there is a great diversity of effects of low B on reproductive growth among species, and within the same species between sites and seasons. Much of this diversity is not explained by the current literature. Key processes in reproductive development which may be impaired under B deficiency are proposed and discussed. These include the formation of a diverse array of cell wall types, the supply of carbohydrates for growth and storage reserves, and the production of flavonols. Inflorescence architecture, floral morphology, canopy structure and prevailing weather conditions are suggested as being important for xylem B delivery into flowers because of their impact on transpiration. The extent of phloem translocation of B into reproductive organs has yet to be fully assessed. The timing of B sensitive stages in reproduction of most crop plants need defining in order to facilitate appropriate timing of corrective B treatments. As most container studies have imposed B deficiency by withholding B, much of the data on severely B-deficient plants requires re-evaluation. Further studies are warranted to understand the effects of realistically low levels of B in solution on the growth of meristematic tissues and floral organs. A B-buffered solution culture system is recommended for some of this work

Boron application in red clover (Trifolium pratense L.) seed production

peer-reviewedThis work is part of the research project TR-31016, funded by the Ministry of Science and Technological Development, Republic of Serbia.A field trial with four red clover cultivars was established on acid soil in order to evaluate the effect of foliar boron application on seed yield. The crop received foliar boron treatment during the second growth of the second year at two applications. Although seed yield showed a significant increase in boron-treated plants in 2011 compared with control (26.0%), its relative increase was far higher in 2010 (43.2%), which had increased total rainfall amounts during flowering. Sufficient level of boron supply to red clover plants for seed production has a remarkably positive effect under conditions hampering pollination and fertilisation.Ministry of Science and Technological Development, Republic of Serbi

Factors controlling equilibrium boron (B) concentration in nutrient solution buffered with B-specific resin (Amberlite IRA-743)

In conventional solution culture where boron (B) is added as boric acid, fluctuating external B supply often produces confounding and ill-defined physiological and biochemical responses in plants, especially when grown at deficient and marginal B supply. Our previous studies proposed the use of the B-specific resin – Amberlite IRA-743 to develop a B-buffered solution culture. The present study aims to evaluate crucial factors determining equilibrium B concentrations in nutrient solution buffered with the B-loaded resin, including the B loading of the resin, pH in the nutrient solution and B removal from the solution. The equilibrium B concentrations in nutrient solution were determined by both the amount of B sorbed by the resin and the solution pH. At pH 6.05±0.05, the relationship between the resin B content and equilibrium B concentration in the nutrient solution is closely described by the equation: Y = 18.8 X1.457 [ where, Y = equilibrium B concentration (μM) in nutrient solution and X = B content of the resin (mg B g−1 moist resin)]. However, at a given resin B content, lowering solution pH from 7 to 4 significantly increased B concentrations in solution through the release of B from the solid phase of the resin beads. The B-loaded resin was capable of maintaining stable B concentrations in the nutrient solutions, ranging from deficient to marginally adequate B concentrations for dicot species. In conclusion, B concentrations ranging from 0.05 to 11 μM, were buffered for 5 days with the resin loaded with 0.004 – 0.691 mg B g−1 moist resin in the nutrient solution. Precise pH control in the nutrient solution is critical for the success of a B-buffered solution culture study