Root Growth Angle (RGA) is a critical trait influencing water and nutrient acquisition in crops, particularly under drought stress. This study investigates the genetic architecture of RGA in a global panel of 1,236 tetraploid wheat accessions, including cultivars (CVS) and Triticum turgidum L. subspecies landraces (TDL), to identify molecular targets for breeding drought-resilient durum wheat. RGA was phenotyped at the early growth stage using a high-throughput filter paper assay focused on seminal roots. Genome-wide association studies (GWAS) were conducted using the Illumina iSelect 90K SNP array, alongside subpopulation-specific analyses. GWAS identified seven high-confidence QTLs in CVS and thirteen in TDL, with major loci validated on chromosomes 2A ( QRGA.ubo.2A.2), 6A (QRGA.ubo.6A.2), and 7A (QRGA.ubo.7A.2). Haplotype analysis revealed alleles associated with narrow (steep) and wide (shallow) RGAs. Narrow RGA haplotypes, which enable deeper root penetration, were linked to enhanced water access under terminal drought and positively associated with grain yield. These haplotypes were more prevalent in varieties developed under rainfed conditions, while shallow RGA alleles were enriched under irrigated regimes. Multi-omics analysis highlighted conserved signaling pathways—including phosphorus response regulators (e.g., PHR1, CLE14) and auxin/ROS-mediated root modulation (e.g., ALMT1 )—underlying RGA plasticity. Meta-QTL analysis and phenotypic correlations further revealed pleiotropic effects of RGA QTLs on yield, biomass, and grain quality, emphasizing RGA’s central role in resource-use efficiency. This study delivers validated KASP® markers and haplotype information for use in marker-assisted selection and haplotype stacking. TDL accessions emerged as a rich source of adaptive alleles for RGA improvement. The findings support a dual breeding strategy: leveraging narrow RGA for deep-water capture and phosphorus-driven root plasticity to enhance drought resilience and yield stability in durum wheat.
Farooq, M.A., Atsbeha, G., Bruschi, M., Makoul, M., Pinto, F., Liu, C., et al. (2025). GENETIC DISSECTION OF ROOT GROWTH ANGLE IN TETRAPLOID WHEAT REVEALS ADAPTIVE HAPLOTYPES FOR DROUGHT RESILIENCE.
GENETIC DISSECTION OF ROOT GROWTH ANGLE IN TETRAPLOID WHEAT REVEALS ADAPTIVE HAPLOTYPES FOR DROUGHT RESILIENCE
FAROOQ M. A.;LIU C.;FORESTAN C.;BOZZOLI M.;SALVI S.;TUBEROSA R.;MACCAFERRI M.
2025
Abstract
Root Growth Angle (RGA) is a critical trait influencing water and nutrient acquisition in crops, particularly under drought stress. This study investigates the genetic architecture of RGA in a global panel of 1,236 tetraploid wheat accessions, including cultivars (CVS) and Triticum turgidum L. subspecies landraces (TDL), to identify molecular targets for breeding drought-resilient durum wheat. RGA was phenotyped at the early growth stage using a high-throughput filter paper assay focused on seminal roots. Genome-wide association studies (GWAS) were conducted using the Illumina iSelect 90K SNP array, alongside subpopulation-specific analyses. GWAS identified seven high-confidence QTLs in CVS and thirteen in TDL, with major loci validated on chromosomes 2A ( QRGA.ubo.2A.2), 6A (QRGA.ubo.6A.2), and 7A (QRGA.ubo.7A.2). Haplotype analysis revealed alleles associated with narrow (steep) and wide (shallow) RGAs. Narrow RGA haplotypes, which enable deeper root penetration, were linked to enhanced water access under terminal drought and positively associated with grain yield. These haplotypes were more prevalent in varieties developed under rainfed conditions, while shallow RGA alleles were enriched under irrigated regimes. Multi-omics analysis highlighted conserved signaling pathways—including phosphorus response regulators (e.g., PHR1, CLE14) and auxin/ROS-mediated root modulation (e.g., ALMT1 )—underlying RGA plasticity. Meta-QTL analysis and phenotypic correlations further revealed pleiotropic effects of RGA QTLs on yield, biomass, and grain quality, emphasizing RGA’s central role in resource-use efficiency. This study delivers validated KASP® markers and haplotype information for use in marker-assisted selection and haplotype stacking. TDL accessions emerged as a rich source of adaptive alleles for RGA improvement. The findings support a dual breeding strategy: leveraging narrow RGA for deep-water capture and phosphorus-driven root plasticity to enhance drought resilience and yield stability in durum wheat.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
