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

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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.