Elucidating the genetic basis of biomass accumulation and radiation use efficiency in spring wheat and its role in yield potential

Abstract

22One of the major challenges for plant scientists is increasing wheat (Triticum aestivum) yield 23 potential (YP). A significant bottleneck for increasing YP is achieving increased biomass through 24 optimization of Radiation Use Efficiency (RUE) along the crop cycle. Exotic material such as 25 landraces and synthetic wheat has been incorporated into breeding programs in an attempt to alleviate 26 this, however their contribution to YP is still unclear. To understand the genetic basis of biomass 27 accumulation and RUE we applied genome-wide association study (GWAS) to a panel of 150 elite 28 spring wheat genotypes including many landrace and synthetically derived lines. The panel was 29 evaluated for 31traits over two years under optimal growing conditions and genotyped using the 35K 30Wheat Breeders array. Marker-trait-association identified 94 SNPs significantly associated with 31 yield, agronomic and phenology related traits along with RUE and biomass at various growth stages 32 that explained 7-17 % of phenotypic variation. Common SNP markers were identified for grain 33 yield, final biomass and RUE on chromosomes 5A and 7A. Additionally we show that landrace and 34 synthetic derivative lines showed higher thousand grain weight (TGW), biomass and RUE but lower 35 grain number (GNO) and harvest index (HI). Our work demonstrates the use of exotic material as a 36 valuable resource to increase YP. It also provides markers for use in marker assisted breeding to 37 systematically increase biomass, RUE and TGW and avoid the TGW/GNO and BM/HI trade-off. 38Thus, achieving greater genetic gains in elite germplasm while also highlighting genomic regions and 39 candidate genes for further study. 40 41

Gene-based mapping of trehalose biosynthetic pathway genes reveals association with source- and sink-related yield traits in a spring wheat panel

“…Strong effects on phenotype have been shown in Arabidopsis thaliana where mutants carrying weak alleles of AtTPS1 showed less T6P than wild-type plants, consequently, reducing vegetative growth (Gómez et al, 2010 Despite the general increase in the phenotypic values of height and peduncle length, we also found a consistent reduction of grains per m 2 . This result was expected as the traits are negatively correlated (Molero et al, 2019) and regulated through the same causative gene (Table 1). This finding suggests that mutations in the TPS1 gene have a large effect on whole plant carbon allocation and growth, potentially through SnRK1 which regulates many genes involved in metabolism and resource allocation (Zhang et al, 2009).…”

“…We did not detect any signals coming from the trehalose biosynthetic pathway in the association mapping using the same HiBAP panel where exome-capture sequencing was not utilised (Molero et al, 2019). Therefore, exomic data is a viable option of narrowing down the relative importance of core network genes (Kiezun et al, 2012) as most of the GWAS hits are outside of genic regions (Visscher et al, 2017).…”

“…The T6P signalling pathway ( Figure 1a) is a central regulatory system of resource allocation and source-sink interactions and is emerging as an important target in crops such as maize, rice, wheat, and sorghum (Paul et al, 2018;Paul et al, 2020). Here for the first time we analysed comprehensive exome SNP information for TPS and TPP genes and dissected the genetic architecture of yield-related traits in a spring wheat diversity panel where all lines presented acceptable agronomic performance (Molero et al, 2019). The data showed significant relationships of TPS and TPP genes with agronomic traits with evidence of historical selection and identified opportunities for future selection of TPS and TPP genes and strategic crossing for yield improvement.…”

“…New diverse populations of wheat have been developed to incorporate a range of variation from elite, synthetic, and exotic materials aiming at increasing genetic gains associated with a better source and sink balance (Reynolds et al, 2007;Reynolds et al, 2009a;Reynolds et al, 2009b;Reynolds et al, 2017). Recently, marker-trait associations have been reported for the High Biomass Association Mapping Panel (HiBAP) consisting of bread spring wheat lines constructed from elite high-yielding material, pre-breeding lines, landraces and synthetically derived lines crossed and selected for high yield and biomass (Molero et al, 2019). However, despite some major contributions of association studies, wheat geneticists are increasingly shifting their attention towards the variation inside genes (i.e.…”

“…In this study, we used enrichment-capture sequencing on 25 TPS and 31 TPP genes (Paul et al, 2018) for the dissection of the genetic architecture of 24 traits in the wheat HiBAP panel (Molero et al, 2019). Our goals were to (i) combine single variant analysis and gene-based approaches for the detection of genetic associations, (ii) evaluate the intragenic patterns of signatures of selection, (iii) estimate the contribution of single gene and the gene families across and within exotic-derived and elite subpopulations, and (iv) explore various approaches of gene-based prediction using TPS and TPP kernels.…”