IWYP Call 2: Transforming yield through source-sink synchronisation

Lead Research Organisation: Rothamsted Research
Department Name: Sustainable Soils and Crops

Abstract

The greatest improvements in crop yields are likely to come from optimising and coordinating the whole plant source-sink system to fully realise photosynthetic potential as grain yield. Emerging research on trehalose 6-phosphate (T6P) has shown that T6P plays a key role in coordinating source and sink activities in crops. Recent novel chemical biology has been used to modify T6P in such a way that it can be used to screen for yield traits. Using T6P precursors as a chemical spray to wheat during early grain filling stimulates starch synthesis in grain increasing starch content, grain size and overall yield by up to 20%. Significantly, this is accompanied by increased photosynthesis in flag leaves due to the enhanced demand created by the sink. This shows that photosynthetic potential may be masked by sink limitations. In addition to its effect on grain size T6P influences initiation and setting of grain number. Through analysis of the response of genetically diverse high-yielding germplasm, T6P precursor will be used as a smart screen for true photosynthetic potential, grain number and size potential as well as biomass and harvest index affected by the harmonisation of source and sink activity. Genome wide association mapping will be performed to discover genomic regions associated with high source and sink and quantitative trait loci will be identified. Given recent examples of association of trehalose phosphate phosphatase genes with crop yield attention will also be given to finding SNPs in trehalose pathway genes as likely genetic variants underlying traits. Outputs will be used at the IWYP Hub to design strategic crosses that maximise genetic complementarity of both source and sink for high yield delivered to breeders in developed and developing countries via the International Wheat Improvement Network.

Technical Summary

The greatest improvements in crop yields are likely to come from optimising and coordinating the whole plant source-sink system to fully realise photosynthetic potential as grain yield. Emerging research on trehalose 6-phosphate (T6P) has shown that T6P plays a key role in coordinating source and sink activities in crops. Recent novel chemical biology has been used to modify T6P in such a way that it can be used to screen for yield traits. Using T6P precursors as a chemical spray to wheat during early grain filling stimulates starch synthesis in grain increasing starch content, grain size and overall yield by up to 20%. Significantly, this is accompanied by increased photosynthesis in flag leaves due to the enhanced demand created by the sink. This shows that photosynthetic potential may be masked by sink limitations. In addition to its effect on grain size T6P influences initiation and setting of grain number. Through analysis of the response of genetically diverse high-yielding germplasm, T6P precursor will be used as a smart screen for true photosynthetic potential, grain number and size potential as well as biomass and harvest index affected by the harmonisation of source and sink activity. Genome wide association mapping will be performed to discover genomic regions associated with high source and sink and quantitative trait loci will be identified. Given recent examples of association of trehalose phosphate phosphatase genes with crop yield attention will also be given to finding SNPs in trehalose pathway genes as likely genetic variants underlying traits. Outputs will be used at the IWYP Hub to design strategic crosses that maximise genetic complementarity of both source and sink for high yield delivered to breeders in developed and developing countries via the International Wheat Improvement Network.

Planned Impact

N/A
 
Description Analysis of a high biomass (HiBAP) wheat diversity panel with a wide range of ancient and modern genetic heritage shows single nucleotide polymorphisms (SNPs) i.e. genetic changes in individual nucleotides in both trehalose phosphate synthase (TPS) and trehalose phosphate phosphatase (TPP) genes that are significantly associated with key agronomic traits important for yield determination. TPS and TPP genes are components of the trehalose 6-phosphate (T6P) sugar signalling pathway with an important role in the allocation of sucrose for growth and development including ears (spike) and grain of wheat. Both individually and combined these SNPs for TPSs or TPPs account for 0.02-0.39 of the heritability of grains per m2, grains per spike, duration of grain filling (TPS only), biomass (TPS only) and days to anthesis. Wheat of elite or exotic background contribute different proportions of the heritability for TPS and TPP genes of different traits. For a single pathway to contribute so much genetic variation and potential to wheat yield traits is very exciting and confirms and extends studies on GM maize where grain numbers could be increased through overexpression of a TPP gene and the T6P precursor effects on grain size and numbers. Such analysis combined with further T6P precursor studies offers great prospect for utilization of the pathway in wheat yield improvement.
Using a wheat population of wide genetic heritage (high biomass association panel, HiBAP) we have found an extraordinary potential in several lines to respond to T6P precursor (DMNB-T6P) applied to spikes 10 days after anthesis at the start of grain filling. Increases were obtained of between +44 to +50% (+0.68 to +0.91 g) in grain weight per spike in top 10 best performing lines. We believe it is likely that this strong responsiveness to T6P comes from the high potential for biomass in this wheat population that is not normally realised in the form of grain yield. There are lines that respond to T6P by increasing grain size as previously observed, but also lines that respond by increasing grain number. Two lines appear capable of increasing both grain size and grain number. Within the population there were also lines that did not respond at all to T6P. One reason could be that photosynthesis in these lines fails to respond to the increased demand from the sink. Although of course there may be other reasons including inability of spikes to respond to applied T6P. Three lines showed a negative response to T6P. One negative responder (HiBAP_38) had SNPs in TraesCS6B02G384500 (TPS11) that was associated with GFR (yield/grain filling duration, g/m2/day) and TraesCS1A02G338200 (TPS7) which was associated with GFR, percentage of grain filling of crop duration, spikes per m2 and grain weight per spike in GWAS of the HiBAP panel. These TPS genes have been proposed as sensors or regulators of T6P synthesis which may be disrupted in HiBAP_38.
Exploitation Route Design crosses to combine beneficial TPS and TPP genes. Use exotic germplasm to include TPP gene variants that may have been lost from elite cultivars.
Design strategies for gene editing of TPS and TPP genes.
Sectors Agriculture, Food and Drink
 
Description Meiotic recombination: how has this adaptive and evolutionary force been influenced by domestication and selective breeding?
Amount £77,744 (GBP)
Funding ID NE/X011585/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 01/2023 
End 07/2023
 
Description Presentation at International wheat yield conference at JIC, Norwich 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This was a presentation at a conference.
Year(s) Of Engagement Activity 2018
 
Description Presentation at International wheat yield partnership (IWYP) conference at Obregon, Mexico 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I made a presentation about the project at the International Wheat Yield Partnership conference in Obregon, Mexico reaching an international audience of researchers.
Year(s) Of Engagement Activity 2019
 
Description Talk at online conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited speaker at Crop Booster P EU workshop "Improving resilience in crops: can we combine high yield and resilience? This contributed to ideas for future directions for EU research funding.
Year(s) Of Engagement Activity 2021
URL https://www.cropbooster-p.eu/