Developing a Cereal Fertility Pipeline (CerFip) for wheat and barley.

There is increasing global awareness of the importance of agriculture and food security. Predictions of a 50% population increase by 2050 emphasise the urgent need for sustainable, effective agricultural systems. Strategies for improved crop productivity without increasing environmental impact are critical. Selective breeding for key traits, combined with the use of hybrid lines has the potential to realise these goals. Hybrids are the progeny derived by crossing two distinct individual together. Hybrids tend to show "hybrid vigour", this can be seen in terms of increased growth, but also overall yield. Hybrid vigour results in the superiority of a hybrid over its parents, for example hybrid rice has 20-30% increased yield compared to inbreds as such hybrids are extremely valuable and in China hybrid rice constitutes >50% of all rice grown. However, the generation of hybrids is difficult and expensive, and has not been easy to achieve in temperate cereals, such as wheat and barley.

Emasculation is often needed to generate hybrids, because plants frequently self-fertilise before cross-fertilising, this is labour intensive, requires specific germplasm, or has high environmental impact. The slow development of hybrid temperate cereals is a reflection of the bottleneck in the availability of germplasm and understanding of traits controlling male fertility. Recently there have been reports of Hystar hybrid wheat (Syngenta) with yield increases of ~0.5t/ha and hybrid barley (Syngenta) showing >10% increased yield. However, these reports are restricted by a lack of molecular understanding of cereal reproduction. There is also a need for subsequent rescue of male sterile lines, therefore approaches involving inducible gene systems, or switches in fertility based on environmental sensitivity are needed. It also seems likely that environmental changes, such as low/high temperature may be impacting on pollen viability and therefore reducing yield.
A better molecular understanding of cereal pollen development that would facilitate effective control of male fertility would aid in increasing yield potential. Much of this knowledge of the molecular processes of pollen development has/is being developed in the model systems of Arabidopsis and Rice. This proposal will exploit this knowledge and utilise newly available techniques in wheat and barley genomic analysis to develop a Cereal Fertility Pipeline (CerFip) for trait transfer from model systems into temperate cereals for the control of male fertility. It will generate germplasm and genetic resources for the manipulation of fertility for selective breeding, maximal fertilization/seed set, and hybrid production, which are essential for yield improvement and food security. It will use comparisons between the different genomes to identify the corresponding genes in barley and wheat. These newly identified genes will be tested to confirm their role in pollen development and provide greater insight into male reproduction in temperate cereals. Germplasm will be developed to test selected genes for their application in switchable systems between male fertility and sterility. Such material will be potentially very valuable in the future development of systems to control fertility for hybrid development.

Improving crop productivity, without increasing environmental impact, is critical if global food security challenges are to be addressed; selective breeding using hybrids has the potential to realise this. Hybrid vigour results in yield increases of 20-30% over inbreds. However generating hybrids is challenging and costly due to the need for emasculation, crossing and fertility rescue. The slow development of hybrid temperate cereals reflects the bottleneck in available germplasm and a lack of molecular understanding of cereal reproduction. This proposal will address this gap. It will facilitate translation of knowledge from models to crops to generate germplasm for application in breeding programmes. As such it will facilitate the improvement of hybrid wheat and barley crops, and provide a greater understanding of male fertility in cereals leading to increased yield potential.

The approaches to be used involve comparative analysis of the gene regulatory networks from Arabidopsis and Rice, to the temperate cereals. Putative barley and wheat genes in pollen regulatory pathways will be functionally tested to identify candidates for potential future deployment. Initial screening will involve bioinformatics and expression analysis, followed by heterologous complementation of Arabidopsis mutants. A high-throughput approach of VIGS will be used to initially test these genes in barley and wheat, combined with subsequent detailed analysis of key targets, using stably transformed RNAi lines. This will facilitate a greater understanding of male reproduction in barley and wheat, and identify candidates for germplasm development.

Wheat male sterile mutants will also be identified by TILLING to develop switchable male fertility systems. Lines carrying homoeologous set of mutations will be tested for effects on pollen development. Inducible systems for controlling fertility by inducible promoters will also be tested in barley as alternative approaches to control fertility.

Food Security is a key global issue and the realisation that we will need to find food to meet a 50% population increase by 2050 provides major focus for strategies to increase agricultural production, but this can not be at the expense of environmental impact. Pollen development is fundamental to plant fertilisation and is vital for the production of most of the food that we eat, therefore understanding male reproduction and providing the means to manipulate this for selective breeding, maximising fertilization and hybrid production are an essential basis for such advances. Providing detailed understanding of the pathway of pollen development is fundamental to the future development of hybrid lines and for selective breeding strategies. The observations that the pathway of plant male reproduction is highly conserved between dicots (Arabidopsis) and monocots (Rice and Barley) (Wilson and Zhang, 2009; Fernandez-Gomez and Wilson in prep) provide a valuable asset since the information obtained from distinct species can be applied to facilitate rapid advances in crops. Outputs from this research provide opportunities for improving crop performance and fall centrally within the CIRC theme "To support research leading to improved crop productivity" and will also help deliver Global Food Security, a strategic priority area supported by the BBSRC.

WHO WILL BENEFIT FROM THE RESEARCH?
- This project will generate important data on the regulatory networks for pollen development in wheat and barley, which will have direct impact on knowledge of plant reproduction, but will critically provide valuable information for plant breeders and biotechnologists. This will provide opportunities for F1 seed production, targeted breeding and for environmental issues relating to the limitation of gene flow and the release of genetically manipulated crops.

- The data will provide information on the pathways and processes of gene regulation for plant development thus allowing deployment of these traits in breeding strategies. This is likely to have impact at all levels from plant breeding companies, specialised researchers, through to schools and textbooks.

- The approaches being adopted will also facilitate new technical developments linked to comparative analysis of regulatory gene network data between dicots and monocots.

HOW WILL THEY BENEFIT?
- By providing intellectual understanding of gene regulation during cereal reproduction and specifically the molecular processes associated with pollen development.
- By the identification and characterisation of targets, and the generation of germplasm for deployment in future breeding programmes for hybrid development.
- By applying information gained on cereal reproduction to mechanism for the switchable regulation of fertility in crops,

- By germplasm resources for switchable control of male fertility in cereals.

IMPACT STRATEGY:
Our work and significance of our data will be imparted in a variety of ways:

- By presentations at the CIRC meetings, at the Project Advisory Board, and by discussions with colleagues in the UK and worldwide.
- Frequent meetings of the Project Advisory Board will ensure transfer of ideas between the researchers and industry, and therefore development of project ideas inline with the goals of Industrial.
- By the deployment of germplasm into commercial breeding programmes.
- By publications in Internationally significant journals, presentation of data at National and International Conferences.
- Information will also be imparted through web sites to provide progress in the research areas.
- Information and ideas linked to Plant Reproduction and GM will also be imparted to Schools, by talks, visits and placements within the PI's group. This provides opportunities to cultivate interests in young people in plant biology.