SummaryTrehalose 6-phosphate (T6P) signalling regulates carbon use and allocation and is a target to improve crop yields. However, the specific contributions of trehalose phosphate synthase (TPS) and trehalose phosphate phosphatase (TPP) genes to source- and sink-related traits remain largely unknown. We used exome-capture sequencing on TPS and TPP genes to estimate and partition the genetic variation of yield-related traits in a spring wheat (Triticum aestivum) breeding panel with diverse genetic heritage. Twelve phenotypes were directly correlated to TPS and TPP genes including final biomass (source) and spikes and grain numbers and grain filling traits (sink) showing indications of both positive and negative gene selection. Additionally, individual genes explained a substantial proportion of heritability (e.g. 3, 12, and 18% of the variance in gene homeologues most closely related to Arabidopsis TPS1 for final biomass), indicating a considerable contribution of this regulatory pathway to the phenotypic variation. Most importantly, two significant missense point mutations in the exon 6 of the TPS1 gene on chromosome 1D substantially increased plant height and peduncle length which was inversely related to grains per m2. Gene-based prediction resulted in significant gains of predictive ability (6% improvement) for grain weight when gene effects were combined with the whole genome markers, potentially helping breeding programs in designing strategic crosses. Three TPS1 homeologues were particularly significant in trait variation. Our study has generated a wealth of information on the role of natural variation of TPS and TPP genes related to yield potential.

Trehalose 6‐phosphate (T6P) signalling regulates carbon use and allocation and is a target to improve crop yields. However, the specific contributions of trehalose phosphate synthase (TPS) and trehalose phosphate phosphatase (TPP) genes to source‐ and sink‐related traits remain largely unknown. We used enrichment capture sequencing on TPS and TPP genes to estimate and partition the genetic variation of yield‐related traits in a spring wheat (Triticum aestivum) breeding panel specifically built to capture the diversity across the 75,000 CIMMYT wheat cultivar collection. Twelve phenotypes were correlated to variation in TPS and TPP genes including plant height and biomass (source), spikelets per spike, spike growth and grain filling traits (sink) which showed indications of both positive and negative gene selection. Individual genes explained proportions of heritability for biomass and grain‐related traits. Three TPS1 homologues were particularly significant for trait variation. Epistatic interactions were found within and between the TPS and TPP gene families for both plant height and grain‐related traits. Gene‐based prediction improved predictive ability for grain weight when gene effects were combined with the whole‐genome markers. Our study has generated a wealth of information on natural variation of TPS and TPP genes related to yield potential which confirms the role for T6P in resource allocation and in affecting traits such as grain number and size confirming other studies which now opens up the possibility of harnessing natural genetic variation more widely to better understand the contribution of native genes to yield traits for incorporation into breeding programmes.

Many biotrophic pathogens, which require living plant tissues for colonization, interact with their hosts in a gene-for-gene (GFG) manner whereby plant disease resistance (R) genes recognize products of specific avirulence (Avr) genes in pathogens leading to disease resistance (Flor, 1956). In these interactions, the absence of either the R gene, or the corresponding Avr gene results in disease. GFG interactions have also been well documented in the pathosystem involving the necrotrophic fungal pathogen Parastagonospora nodorum (also known as Septoria, Stagonospora, Leptosphaeria and Phaeosphaeria nodorum) and wheat. However, in this case, the interactions lead to increased disease when Parastagonospora nodorum expresses specific necrotrophic effector (NE) genes and wheat contains the corresponding dominant sensitivity genes. This type of interaction is often described as an 'inverse' GFG (Fig. 1).