Genetic control of duration of pre-anthesis phases in wheat (Triticum aestivum L.) and relationships to leaf appearance, tillering, and dry matter accumulation

The duration of pre-anthesis developmental phases is of interest in breeding for improved adaptation and yield potential in temperate cereals. Yet despite numerous studies on the genetic control of anthesis (flowering) time and floral initiation, little is known about the genetic control of other pre-anthesis phases. Furthermore, little is known about the effect that changes in the duration of pre-anthesis phases could have on traits related to leaf appearance and tillering, or dry matter accumulation before terminal spikelet initiation (TS). The genetic control of the leaf and spikelet initiation phase (LS; from sowing to TS), the stem elongation phase (SE; from TS to anthesis), and, within the latter, from TS to flag leaf appearance and from then to anthesis, was studied in two doubled-haploid, mapping bread wheat populations, Cranbrook×Halberd and CD87×Katepwa, in two field experiments (ACT and NSW, Australia). The lengths of phases were estimated from measurements of both TS and the onset of stem elongation. Dry weight per plant before TS, rate of leaf appearance, tillering rate, maximum number of tillers and number of leaves, and dry weight per plant at TS were also estimated in the Cranbrook×Halberd population. More genomic regions were identified for the length of the different pre-anthesis phases than for total time to anthesis. Although overall genetic correlations between LS and SE were significant and positive, independent genetic variability between LS and SE, and several quantitative trait loci (QTLs) with different effects on both phases were found in the two populations. Several of these QTLs (which did not seem to coincide with reported major genes) could be of interest for breeding purposes since they were only significant for either LS or SE. There was no relationship between LS and the rate of leaf appearance. LS was strongly and positively correlated with dry weight at TS but only slightly negatively correlated with early vigour (dry weight before TS). Despite significant genetic correlations between LS and some tillering traits, shortening LS so as to lengthen SE without modifying total time to anthesis would not necessarily reduce tillering capacity, as QTLs for tillering traits did not coincide with those QTLs significant only for LS or SE. Therefore, the study of different pre-anthesis phases is relevant for a better understanding of genetic factors regulating developmental time and may offer new tools for fine-tuning it in breeding for both adaptability and yield potential

Weathering, erosion and element mobilisation in a catchment at the Luxemburg Copper/Gold site, Olary Domain, South Australia

This item is only available electronically.The Olary Domain, Curnamona Province has significant economic importance as a target for base metal and gold exploration. A veneer of Cainozoic or younger regolith occurs over large areas of the Olary Domain, which complicates mineral exploration. The study area is located within a small catchment at the old Luxemburg Cu/Au mining site in the mid North of South Australia in the Southern area of the Olary Domain. This investigation focuses on relating physical and chemical weathering processes present between basement amphibolite, granites and gneisses and a local waterway, including parameters such as bedrock geochemistry, regolith profile interpretation, channel morphology, and landscape evolution. Mapping the extent and character of the regolith in the Luxemburg area in a detailed Regolith Landform Map was also a large feature of this study. Results from the Regolith Landform Map allow inferences on the present day surface dispersion pathways. Geochemical investigations of the regolith profile within the catchment indicate a considerable fingerprint from the underlying amphibolite, specifically shown by Fe, Ti, Ni, Cr, V and Sc values. The elemental signature of the surface regolith reflects the underlying parent regolith units. Geochemical patterns within the ephemeral channel can be related to source geology, streambed morphology and landscape position. Harker plots and grain size analysis indicate that the channel sediment is chemically immature and La/Sc plots against Ti, Zr and Th illustrate that the amphibolite body primarily controls its elemental signature. The geochemistry of the underlying moderately weathered bedrock can be seen and deciphered in an area of iron rich, relatively thin regolith. Bedrock signatures are also evident within the chemistry of bulk samples from the local ephemeral channel deposits. Recent mining activity within the area does not seem to have influenced the results of this study.Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 200

Treatment Failure in Vertebral Osteomyelitis Is it All About Staphylococcus aureus?

Study Design. Retrospective cohort study. Objective. The aim was to compare the influence of 2 common vertebral osteomyelitis (VO) causing pathogens on treatment failure within the first year of diagnosis. Summary of Background Data. VO is mainly caused by Staphylococcus aureus (SA), while enterococci and streptococci (ENST) are also responsible for a significant proportion of VO, particularly in elderly patients. Data on VO caused by SA show a tendency for worse outcome, whereas data on VO caused by ENST are scarce. For this purpose, our study compares characteristics of patients with VO caused by SA or ENST in order to analyze risk factors for treatment failure. Methods. We conducted a retrospective monocentric study including VO patients from 2008 to 2020. Primary outcome was treatment failure defined as death or relapse within 1 year (T1). We compared patients diagnosed with VO caused by Staphylococcus aureus including MRSA to patients diagnosed with VO caused by Enterococcus and Streptococcus species, which were combined into one group. Polymicrobial infections were excluded. We employed multiple logistic regression analysis to adjust for confounding. To account for moderation, the model was repeated with an included interaction term. Results. Data of 130 VO patients (SA=95; ENST=35) were available at T1. Treatment failure occurred in 37% of SA patients and 23% of ENST patients. On multivariate analysis SA [odds ratio (OR): 3.12; 95% confidence interval (CI): 1.09-10.53; P=0.046], Charlson comorbidity index (OR: 1.31; 95% CI: 1.11-1.58; P=0.002) and infectious endocarditis (IE; OR: 4.29; 95% CI: 1.23-15.96; P=0.024) were identified as independent risk factors for treatment failure. Conclusion. In our cohort every third patient with VO caused by SA or ENST dies within 1 year. Our findings indicate that patients with VO caused by SA, concomitant IE and/or a high Charlson comorbidity index score may be at elevated risk for treatment failure. These findings can be used to individualize patient care and to direct clinical surveillance. This could include echocardiography evaluating for the presence of IE in patients with VO caused by gram-positive pathogens