Developing systems to control male fertility in wheat for hybrid breeding, enhanced pollen production and increased yield.

Control of fertility and successful reproduction is key to grain set and thus crop yield in cereals. Self-pollinating crops tend to have lower yield capability than hybrids generated by intercrossing between elite lines. This "Hybrid Vigour" has been shown to increase yield, but also abiotic and biotic stress resistance. Hybrid crops thus provide opportunities to increase yield and productivity in a sustainable manner. However, the challenge for hybrid production is the need to avoid the natural tendency for many crops to self-fertilise prior to outcrossing, whilst ensuring effective cross-pollination for hybrid seed production. Mechanisms that control fertility in a reversible manner are critical to deliver such systems and this is a key goal for wheat breeding, since major yield enhancements are possible from hybrid wheat. Hybrid seed production also relies upon effective males to pollinate the female lines, therefore traits for optimal pollen production, viability and release are also of major importance.

Wheat pollen development is particularly sensitive to environmental damage, with rapid reductions in viability post anthesis, combined with general sensitivity to abiotic stress (e.g. high and low temperature) during development. Reductions in fertility due to environmental stress are often seen in wheat crops and these can have major impacts on yield. Reproductive resilience to variable environmental conditions and abiotic stress is therefore critical to sustainable yields. This can only be delivered by detailed knowledge of pollen development and systems to regulate fertility. Deep understanding of cereal reproduction is therefore key to the development of wheat hybrid breeding systems.

This proposal will address these issues by providing greater understanding of pollen development in cereals towards developing switchable systems for the control of wheat fertility, but also by identifying traits for enhanced pollen production and viability, particularly under environmental stress, which are critical for ensuring successful pollination in breeding programmes. By investigating the mechanisms behind these traits and by generating tools for breeding and selection, effective breeding to increase crop productivity and resilience will be realised.

The project will use our progress in understanding cereal pollen development to develop systems for controlling cereal fertility, focussing on wheat. In addition introgression lines and breeding populations will be screened to identify traits for optimal fertilisation, including high pollen production, release and durability. These will be focused around the impact of environment, particularly temperature and day length, on pollen fertility. We will determine the benefit and stability of these traits in elite commercial germplasm, enabling their potential to be determined. We will also assess natural variation at these fertility loci and develop markers to enable these traits, which could potentially impact on fertility particularly under different environmental conditions, to be followed in breeding populations.

Successful reproduction is critical to grain set and crop yield in cereals. Thus optimizing and enhancing fertility, alongside controlled fertilization for breeding and hybrid development, is key to achieve high yields in a sustainable manner. Hybrid vigour increases yield, therefore hybrid crops offer opportunities to increase productivity. However to produce hybrid seed there is a need to avoid self-fertilization, therefore mechanisms that control fertility in a reversible manner are required. Alongside controlled fertility to avoid self-pollination of the "female", there is also a need to ensure effective cross-pollination, which relies on high levels of viable pollen for cross-pollination that is distributed effectively and is resilient to abiotic stress.

This project will use our understanding of cereal pollen development to address these challenges by providing in depth understanding of pollen development in cereals with the aim of developing switchable systems for the control of wheat fertility. These will focus upon the impact of environment on pollen development and reversible systems for viable pollen production. In addition the project will target traits associated with maximizing cross-pollination. Wheat lines will be screened to identify traits for enhanced pollen production, release and viability, particularly under temperature stress, which are critical for ensuring successful pollination in breeding programmes. By investigating the mechanisms behind these traits and by generating tools for breeding and selection, effective breeding to increase crop productivity and resilience will be realised.

Global populations are continuously growing and demand is increasing not only for more food, but also for increased food quality in a sustainable manner. Control of fertility and successful reproduction is key to grain set and thus crop yield in cereals. Optimizing and enhancing fertility, alongside controlled fertilization for breeding and hybrid development, is critical to achieve high yields in a sustainable manner.

"Hybrid Vigour" has been shown to increase yield, but also abiotic and biotic stress resistance. For example rice yield increases of 20-30% have been achieved in hybrids compared to inbreds. However, the challenge for hybrid production is to avoid self-fertilisation prior to outcrossing, whilst ensuring effective cross-pollination for hybrid seed production. Hybrid crops thus provide opportunities to increase yield and productivity in a sustainable manner. Mechanisms that control fertility in a reversible manner are critical to deliver such systems; this is a key goal for wheat breeding with major yield enhancements possible from hybrid wheat. Potential yield advantages are available from deployment of hybrid wheat, thus providing opportunities to help address issues of future food security. Detailed understanding of cereal reproduction is key to the development of hybrid breeding systems. Wheat pollen development is also particularly sensitive to environmental damage, with rapid reductions in viability post anthesis, thus reproductive resilience to variable environmental conditions and abiotic stress is critical to sustainable yields. It is therefore essential to have detailed understanding of pollen development and systems to regulate fertility, alongside traits to maximise pollen production, release and resilience.

This project will use our understanding of cereal pollen development to develop systems for controlling cereal fertility in wheat and to identify traits for optimal fertilisation, including high pollen production, release and durability. These will also be focused upon the impact of environment, particularly temperature and day length, on pollen fertility. We will determine the benefit and stability of these traits in elite commercial germplasm, enabling their potential to be determined.

WHO WILL BENEFIT FROM THE RESEARCH?
- Outputs from this project have potential for significant impact on wheat breeding, production and crop resilience. These issues are of major importance to Breeding Companies, Farmers, and Producers, and in turn to consumers. This is evident from the high level of commitment from Plant Breeding Companies in this proposal.
- The ultimate impact from these outputs will be the production of systems for controlled fertility for wheat hybrid breeding for enhanced yields; enhanced pollen production and durability to maximise fertilisation in the field and greater resilience in wheat reproduction. Outputs from this research thus provide opportunities for improving crop performance and help deliver food security, a strategic priority area of the BBSRC.
- Outputs will also provide valuable information on the pathways and processes of cereal reproduction for Researchers in plant reproduction. This is likely to have impact at all levels from specialised Researchers, through to schools and textbooks.

HOW WILL THEY BENEFIT?
- By generating germplasm and data on cereal reproduction with the aim of controlling fertility and maximizing effective pollen production.
- By the development of techniques for field phenotyping of fertility traits in wheat.
- By enabling basic research to be applied to male reproduction in crops. Data generated will be stored in according to UKAS guidelines and published in peer-reviewed journals.
- By understanding gene regulation mechanisms in the anther during pollen formation, which can be translated to other crops to enhance fertility.