In this section:
PhD Project
PhD projects currently being offered:
Wheat adaptation to drought: disentangling genotype by environment interactions
Supervisors
Dr Thorsten Schnurbusch
Acting Professor Victor Sadras
Background
A certain phenotype (P) results from the influence of genetic (G) and environmental (E) factors, and often strong GxE interactions. These interactions frequently constrain our ability to interpret genetic control of key traits, and could represent a major obstacle for effective breeding progress. Currently, this interaction is modelled in terms of the genotypic sensitivity b to environmental variable Z , ie GxE = bZ. Furthermore, b can be associated with QTLs, and rapidly developing techniques of molecular genetics combined with biometrics allow for powerful, top-down characterisation of GxE. In practice, this involves screening a large number of lines grown in a range of environments, and a posteriori analysis of GxE.
This project proposes a complementary, approach whereby (a) hypothetical GxE interactions are derived from first principles of crop physiology and environmental characterisations such as predicting root patterns required to capture small vs large rainfall events, and (b) the expected GxE is tested experimentally. For instance, a characterisation of rainfall patterns in a transect from Emerald (Qld) to Horsham (Victoria) in eastern Australia indicates a shift from summer to winter rainfall, and a shift from large to small events. Deep root systems would be highly adaptive in the Emerald-type environment, where summer rainfall and large events ensure a high likelihood of wet soil profiles at the beginning of the season. Conversely, shallow root systems with rapid capacity to respond to topsoil wetting would be more relevant in Horsham-type environments – ie shallow root system favoured in the south and deeper in the north.
Aim
Develop a novel approach to elucidate GxE relevant to drought adaptation in annual crops.
Objectives
(a) Characterise the environments (soil and climate) in a transect across eastern Australia
(b) Identify wheat lines with contrasting traits for phenotypic evaluations in diverse environments across eastern Australia
(c) Relate traits in contrasting environments to known genetic differences
(d) Formulate hypotehses on GxE related to drought adaptation of wheat in contrasting environments
(e) Design experiments to test hypothetical GxE
Techniques
You will:
(i) work at the interface between environmental science, genetics and crop physiology;
(ii) develop original laboratory, glasshouse and field experiments; and
(iii) adapt existing or develop new ad-hoc computer models of plant growth in response to key environmental variables in relation to drought.
Interactions/ Partnerships
SARDI will contribute a top-up scholarship ($5000 per year)
Further reading
Rodriguez D and Sadras VO (2007) The limit to wheat water use efficiency in eastern Australia. I. Gradients in the radiation environment and atmospheric demand. Australian Journal of Agricultural Research 58 (4).
Schwinning S and Ehleringer JR (2001) Water-use trade-offs and optimal adaptations to pulse-driven arid ecosystems. Journal of Ecology 89, 464-480.
