Republished from the Australian Plant Phenomics Facility blog.
Two international consortia of scientists from the United States, Great Britain, Mexico and Australia are currently carrying out research projects of global importance at the Australian Plant Phenomics Facility’s (APPF) Adelaide node for the International Wheat Yield Partnership (IWYP).
The first research project, Improving Yield by Optimising Energy Use Efficiency, is phenotyping an Excalibur x Kukri RIL population to determine genetics controlling energy use efficiency (EUE) in wheat. The aim is to identify genetic loci and markers to enable breeding of high-yielding germplasm with:
- low rates of leaf respiratory CO2 released per unit growth,
- optimised levels of sugars, organic and amino acids for growth, and
- increased biomass at anthesis.
More than 85-90% of the energy captured by plants is used in high-cost cellular processes, such as transport of nutrients and respiration, meaning about only 10-15% is allocated to yield. Thus, any small gain in energy redistribution and use for a costly process can have a marked positive impact on biomass accumulation and yield.
Improvements in EUE can be achieved at the cell, tissue and whole-plant level, with respiration being a prime target.
“Our initial screening of 138 Australian commercial cultivars revealed a two-fold variation in rates of leaf respiration, three-fold variation in the ratio of respiration to growth rate during early development, and significant heritability of 35%. This demonstrates there is untapped genetic variation in EUE amenable to fine-tuning and optimisation of biomass accumulation in the lead-up to anthesis, with concomitant positive knock-on effects on yield”, said Australian National University’s Barry Pogson, Project Lead and Director of the ARC Centre of Excellence in Plant Energy Biology (AUS).
The project has partners at University of Western Australia (AUS), CIMMYT (MEX) and the University of Adelaide (AUS).
The second research project, AVP1, PSTOL1 and NAS – Three High-Value Genes for Higher Wheat Yield, aims to enhance wheat yield by exploiting and building synergy of three high value genes (AVP1, PSTOL1 and NAS) and enabling molecular breeding by:
- developing two-gene and three-gene pyramiding combinations of AVP1, PSTOL1 and NAS using available transgenic wheat lines and quantifying the additive effects on yield in multi-location field and greenhouse trials (as a proof of concept),
- identifying wheat orthologs and allelic variants of TaAVP1, TaPSTOL1 and TaNAS, and designing molecular markers to the best alleles for marker-assisted breeding,
- providing basic understanding of the physiological and molecular mechanisms behind improved yield and selecting wheat lines with the best allelic combination and field performance, and
- assessing the necessity for using genome editing technologies to optimise gene function and enhance positive effect on wheat yield by modifying expression of the wheat alleles.
The genes Vacuolar Proton Pyrophosphatase 1 (AVP1), Phosphorus Starvation Tolerance 1 (PSTOL1) and Nicotianamine Synthase (NAS) have been shown to improve plant biomass production and grain yield. Over-expression of these genes results in improved biomass production and grain yield in a range of plant species, including cereals (rice, barley, wheat), in optimal growing conditions. The enhanced yield of the plants is believed to be due to improved sugar transport from source to sinks (AVP1), enhanced root growth and nutrient uptake (AVP1, PSTOL1) and increase in shoot biomass and tiller number (AVP1, PSTOL1, NAS2).
“Identifying and pyramiding the wheat orthologues of these high-value genes provides a real opportunity to produce wheat with significantly improved field performance and higher grain yield,” said Project Lead, Stuart Roy, from the University of Adelaide (AUS).
The project has partners at University of Melbourne (AUS), Arizona State University (USA), Cornell University (USA), University of California, Riverside (USA) and Rothamsted Research (GBR).
These extensive projects will continue throughout 2017 and into 2018.