An international wheat diversity panel reveals novel sources of genetic resistance to tan spot in Australia.

KEY MESSAGE: Novel sources of genetic resistance to tan spot in Australia have been discovered using one-step GWAS and genomic prediction models that accounts for additive and non-additive genetic variation. Tan spot is a foliar disease in wheat caused by the fungal pathogen Pyrenophora tritici-repentis (Ptr) and has been reported to generate up to 50% yield losses under favourable disease conditions. Although farming management practices are available to reduce disease, the most economically sustainable approach is establishing genetic resistance through plant breeding. To further understand the genetic basis for disease resistance, we conducted a phenotypic and genetic analysis study using an international diversity panel of 192 wheat lines from the Maize and Wheat Improvement Centre (CIMMYT), the International Centre for Agriculture in the Dry Areas (ICARDA) and Australian (AUS) wheat research programmes. The panel was evaluated using Australian Ptr isolates in 12 experiments conducted in three Australian locations over two years, with assessment for tan spot symptoms at various plant development stages. Phenotypic modelling indicated high heritability for nearly all tan spot traits with ICARDA lines displaying the greatest average resistance. We then conducted a one-step whole-genome analysis of each trait using a high-density SNP array, revealing a large number of highly significant QTL exhibiting a distinct lack of repeatability across the traits. To better summarise the genetic resistance of the lines, a one-step genomic prediction of each tan spot trait was conducted by combining the additive and non-additive predicted genetic effects of the lines. This revealed multiple CIMMYT lines with broad genetic resistance across the developmental stages of the plant which can be utilised in Australian wheat breeding programmes to improve tan spot disease resistance.

Loci on chromosomes 1A and 2A affect resistance to tan (yellow) spot in wheat populations not segregating for tsn1.

KEY MESSAGE: QTL for tan spot resistance were mapped on wheat chromosomes 1A and 2A. Lines were developed with resistance alleles at these loci and at the tsn1 locus on chromosome 5B. These lines expressed significantly higher resistance than the parent with tsn1 only. Tan spot (syn. yellow spot and yellow leaf spot) caused by Pyrenophora tritici-repentis is an important foliar disease of wheat in Australia. Few resistance genes have been mapped in Australian germplasm and only one, known as tsn1 located on chromosome 5B, is known in Australian breeding programs. This gene confers insensitivity to the fungal effector ToxA. The main aim of this study was to map novel resistance loci in two populations: Calingiri/Wyalkatchem, which is fixed for the ToxA-insensitivity allele tsn1, and IGW2574/Annuello, which is fixed for the ToxA-sensitivity allele Tsn1. A second aim was to combine new loci with tsn1 to develop lines with improved resistance. Tan spot severity was evaluated at various growth stages and in multiple environments. Symptom severity traits exhibited quantitative variation. The most significant quantitative trait loci (QTL) were detected on chromosomes 2A and 1A. The QTL on 2A explained up to 29.2% of the genotypic variation in the Calingiri/Wyalkatchem population with the resistance allele contributed by Wyalkatchem. The QTL on 1A explained up to 28.1% of the genotypic variation in the IGW2574/Annuello population with the resistance allele contributed by Annuello. The resistance alleles at both QTL were successfully combined with tsn1 to develop lines that express significantly better resistance at both seedling and adult plant stages than Calingiri which has tsn1 only.

Young adult women's experiences of body image after bariatric surgery: a descriptive phenomenological study.

AIM: To understand the lived experience of body image in young women after obesity surgery. BACKGROUND: Quantitative studies have documented that health-related quality of life and body image are improved after bariatric surgery, probably due to significant weight loss. Female obesity surgery candidates are likely to be motivated by dissatisfaction regarding physical appearance. However, little is known about the experience of the individual woman, leaving little understanding of the association between bariatric surgery and changes in health-related quality of life and body image. DESIGN: A qualitative descriptive phenomenological study. METHODS: Data were collected over 4 months during 2010. Selection for interview was carried out through purposeful sampling. The participants were five young women who underwent bariatric surgery (range: 1-12 months). In-depth, semi-structured interviews were analysed by systematic text condensation influenced by Giorgi's phenomenological method and supplemented by elements from narrative analysis. FINDINGS: The analysis revealed three concepts: solution to an unbearable problem, learning new boundaries and hopes of normalization. These revelatory concepts were synthesized into one major theme: on the edge of control, that is describing these women's feelings of being on the edge of balance between control and loss of control. CONCLUSION: Perception of control may be an essential aspect of body image and the key to understanding these young women's feelings of empowerment and quality of life through body control postbariatric surgery. Future studies should focus on how body control is an essential aspect of body image, which may contribute to long-term weight loss maintenance and improve quality of life.