Michael John Foulkes

Summary: The grain quality traits of protein content, grain weight and size are socially and economically important for wheat ( Triticum aestivum ) breeding. Modern wheat germplasm has limited genetic variation for vital traits, including grain quality, underscoring the need to investigate ancestral varieties/landraces for beneficial allelic diversity. Here, we develop a reliable and sensitive single‐seed hyperspectral imaging‐based phenotyping platform to quantify grain protein, weight and size in 827 diverse wheat landraces, achieving improved predictive accuracy ( R ² = 0.91) vs previous methods. We identified novel genetic variants (or loci) for grain protein content and its heterogeneity between individual grains in a genotype, and grain weight, and validated them through bi‐parental linkage mapping. Many loci we report are rare and absent from modern breeding germplasm. Beneficial haplotypes at these loci improved mean protein content and homogeneity without compromising grain weight; these haplotypes represent valuable genetic variation for agriculture. We identify a stable locus on chromosome 6A contributing to protein heterogeneity within single grains, suggesting homogeneity in protein content could be a selectable trait for breeding. Our findings demonstrate how integration of advanced phenotyping into breeding strategies can harness untapped genetic diversity for grain quality improvement in wheat, providing an opportunity to enhance grain nutritional value.

MicroRNA-resistant alleles of HOMEOBOX DOMAIN-2 ( HB-2 ) were recently reported to improve grain protein content (GPC) in wheat by modifying vascular development in stems to increase amino acid distribution to grain. However, it is not known if these alleles increase GPC at the expense of other physiologically important traits, such as senescence and yield-component traits. Here, we evaluated the effects of mutations in HB-2 on grain yield and nitrogen (N)-use efficiency as well as senescence and plant architecture in multi-environment glasshouse and field experiments. In glasshouse experiments, the mutations in HB-2 moderately improved GPC irrespective of N supply and without accelerating senescence or decreasing grain number or weight compared to the wildtype spring wheat cv. Cadenza. The trait analysis indicated mutant plants were more tolerant of N limitation in terms of above-ground N reduction compared to the wild type. The expression of all HB-2 homeologues increased in spikes at the lemma primordium stage in response to N limitation, indicating the later GPC increase could be a result of enhanced N sink strength determined during early development, rather than processes caused by direct changes in HB-2 expression in the grain. In field experiments, the introgression of HB-2 alleles into Australian elite spring wheat cultivars significantly improved GPC without compromising grain yield. The outcomes of this study support the introduction of miRNA-resistant HB-2 alleles, with a preference to HB-A2 , into commercial wheat for improving grain quality without a yield penalty.

There is an increasing emphasis worldwide on breeding wheat cultivars with higher biomass and grain yield, whilst reducing excessive input of N fertilizers. Modern plant breeding has narrowed the genetic base of bread wheat, so exploring new sources of genetic variation for leaf photosynthesis traits and biomass to underpin grain yield improvement has become necessary. Our objectives were to quantify the genetic variability in a range of landrace-derived lines and elite bread wheat genotypes in flag-leaf photosynthesis traits, biomass and N-use efficiency for potential application in pre-breeding. Sixteen bread wheat genotypes including elite spring wheat cultivar Paragon × landrace crosses were tested in two field experiments in the UK. Averaging across years, pre-anthesis flag-leaf photosynthesis rate ranged amongst genotypes from 26.0 to 31.5 μmol/m²/s (P < 0.001) and post-anthesis from 14.2 to 18.6 μmol/m²/s (P < 0.001). Two landrace-derived lines had greater post-anthesis flag-leaf photosynthesis rate (P < 0.001) than their elite parent Paragon. There was a trend for a positive correlation among genotypes between post-anthesis flag-leaf photosynthesis rate and biomass (r = 0.47, P = 0.06). Two landrace derivatives showed higher post-anthesis flag-leaf stomatal conductance than Paragon. Our results indicated that introgression of traits from wider germplasm into elite UK modern wheat germplasm offers scope to raise flag-leaf photosynthetic rate and biomass.

Radiation‐use efficiency (RUE) is an important trait for raising biomass and yield potential in plant breeding. However, the effect of the planting system (PS) on genetic variation in RUE has not been previously investigated. Our objectives were to quantify genetic variation in RUE, biomass and grain yield in raised‐bed and flat‐basin planting systems, and associations with canopy‐architecture traits (flag‐leaf angle and curvature). Twelve spring wheat (Triticum aestivum L.) cultivars were evaluated under irrigated conditions for 3 years in North West Mexico using raised‐bed and flat‐basin planting systems. Canopy architecture traits were measured at booting and anthesis + 7 days. Grain yield (10.6%), biomass (7.6%), and pre‐grain‐filling RUE (9.7%) were higher in raised beds than flat basins, while a significant planting system × genotype interaction was found for grain yield. Genetic variation in pre‐grain‐filling RUE was associated with biomass and grain yield in beds and basins. In flat basins, higher pre‐grain‐filling RUE was correlated with a more upright flag‐leaf angle but not in raised beds. In raised beds, cultivars with less upright flag‐leaf angle had greater fractional light interception pre‐anthesis. Taller semi‐dwarf cultivars intercepted relatively more radiation in the beds than the flats before anthesis, consistent with the taller cultivars showing relatively greater increases in yield in beds compared to flats. Our results indicated that the evaluation of genotypes for RUE and biomass in wheat breeding should take into account planting systems to capture genotype × PS effects. In addition, the results demonstrate how flag‐leaf angle has a different effect depending on the planting system.

Breeding crops resilient to climate change is urgently needed to help ensure food security. A key challenge is to harness genetic diversity to optimise adaptation, yield, stress resilience and nutrition. We examined the genetic and phenotypic diversity of the A.E. Watkins landrace collection of bread wheat ( Triticum aestivum ), a major global cereal, through whole-genome re-sequencing (827 Watkins landraces and 208 modern cultivars) and in-depth field evaluation spanning a decade. We discovered that modern cultivars are derived from just two of the seven ancestral groups of wheat, leaving five groups as previously untapped sources for breeding. This provides access to landrace-specific functional variations using structured germplasm, genotyping and informatics resources. Employing complementary genetic populations and approaches, we identified thousands of high-resolution quantitative trait loci (QTL) and significant marker–trait associations for major traits, revealing many Watkins-unique loci that can confer superior traits in modern wheat. Furthermore, we identified and functionally verified causative genes for climate-change adaptation, nutritional enhancement and resistance to wheat blast. Finally, we assessed the phenotypic effects of 44,338 Watkins-unique haplotypes, introgressed from 143 prioritised QTL in the context of modern cultivars, bridging the gap between landrace diversity and current breeding. This study establishes a framework for systematically utilising genetic diversity in crop improvement to achieve sustainable food security.

A long‐term goal of breeders and researchers is to develop crop varieties that can resist environmental stressors and produce high yields. However, prioritising yield often compromises improvement of other key traits, including grain quality, which is tedious and time‐consuming to measure because of the frequent involvement of destructive phenotyping methods. Recently, non‐destructive methods such as hyperspectral imaging (HSI) have gained attention in the food industry for studying wheat grain quality. HSI can quantify variations in individual grains, helping to differentiate high‐quality grains from those of low quality. In this review, we discuss the reduction of wheat genetic diversity underlying grain quality traits due to modern breeding, key traits for grain quality, traditional methods for studying grain quality and the application of HSI to study grain quality traits in wheat and its scope in breeding. Our critical review of literature on wheat domestication, grain quality traits and innovative technology introduces approaches that could help improve grain quality in wheat.