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

Abstract

Summary One of the major challenges for plant scientists is increasing wheat ( Triticum aestivum ) yield potential ( YP ). A significant bottleneck for increasing YP is achieving increased biomass through optimization of radiation use efficiency ( RUE ) along the crop cycle. Exotic material such as landraces and synthetic wheat has been incorporated into breeding programmes in an attempt to alleviate this; however, their contribution to YP is still unclear. To understand the genetic basis of biomass accumulation and RUE , we applied genome‐wide association study ( GWAS ) to a panel of 150 elite spring wheat genotypes including many landrace and synthetically derived lines. The panel was evaluated for 31 traits over 2 years under optimal growing conditions and genotyped using the 35K wheat breeders array. Marker‐trait association identified 94 SNP s significantly associated with yield, agronomic and phenology‐related traits along with RUE and final biomass ( BM _ PM ) at various growth stages that explained 7%–17% of phenotypic variation. Common SNP markers were identified for grain yield, BM _ PM and RUE on chromosomes 5A and 7A. Additionally, landrace and synthetic derivative lines showed higher thousand grain weight ( TGW ), BM _ PM and RUE but lower grain number ( GM 2) and harvest index ( HI ). Our work demonstrates the use of exotic material as a valuable resource to increase YP . It also provides markers for use in marker‐assisted breeding to systematically increase BM _ PM , RUE and TGW and avoid the TGW / GM 2 and BM _ PM / HI trade‐off. Thus, achieving greater genetic gains in elite germplasm while also highlighting genomic regions and candidate genes for further study.

Uncovering candidate genes involved in photosynthetic capacity using unexplored genetic variation in Spring Wheat

“…The High Biomass Association Mapping Panel (HiBAP) consists of 149 bread wheat spring types (ST6) that are agronomically acceptable including elite high yielding lines, pre-breeding lines that have been selected for high yield and/or biomass, including lines that have "exotic" material such as landraces or synthetic primary hexaploids in their recent pedigree history along with appropriate local check lines. The panel contains members that show broad variation of both RUE and biomass at multiple growth stages as described in 22 , and are controlled for the confounding effects of the extremes of height and phenology.…”

“…Plots were fertilized with 50 kg N ha −1 (urea) and 50 kg P ha −1 at soil preparation, 50 kg N ha −1 with the first irrigation and another 150 kg N ha −1 with the second irrigation. Growing conditions and main agronomic characteristics of the trial grown for two years are detailed in 22 .…”

“…Agronomical and physiological characterization was conducted as detailed in 22 . In summary, two replicates were measured for the different traits with the exception of phenology, yield, thousand grain weight (TGW) and grain number per m 2 (GNO) where four replicates were scored.…”

“…Few studies have attempted to determine these traits' contribution to a plant's efficiency in utilisation of incident solar radiation (or radiation use efficiency, RUE), which determines crop productivity 21 . Our mechanistic understanding of the genes and pathways involved in RUE is therefore limited, especially under field conditions 22 .…”

“…To understand the genetic causes of this variation, traits contributing to RUE must be studied. Molero et al, 2019 proposed the use of exotic material (landrace and synthetic-derivative lines) as a resource to increase RUE. Previous work has uncovered multiple marker trait associations (MTAs) related to RUE and biomass accumulation at various phenological stages 22 and demonstrated a link between RUE and photoprotection.…”