Characterizing Developmental Traits for Grain Yield Enhancement in Tetraploid Wheat Core Collection: Focus on Spike Fertility and Grain Morphology

Durum wheat (Triticum turgidum ssp.) is a key staple crop facing pressure to meet rising global food demands. Understanding the genetic basis of yield traits is essential for developing climate-resilient, high-yielding cultivars. To support this, accessions from the Tetraploid Germplasm Collection (TGC, Maccaferri et al., 2019) and the Global Durum Panel (GDP, Mazzucotelli et al., 2020) were evaluated for seed and spike traits in Grosseto (2018). A panel of approximately 500 accessions, including modern durum cultivars, T. turgidum landraces, and both domesticated and wild emmer, was assembled as the Tetraploid Core Collection (TCC). The TCC was genotyped with the 90K SNP array to assess diversity linked to yield traits. Field trials were conducted over three seasons (2020, 2022, and 2024) in Granarolo Emilia (BO) using a 1 m² unreplicated modified augmented design with random checks. Ten main spikes per accession were analyzed for morphology, fertility, and grain traits. Threshed kernels were weighed and scanned to evaluate size, shape, and color. The panel showed broad phenotypic variation, confirming high genetic diversity and the value of ancestral germplasm for wheat improvement. A Genome-Wide Association Study (GWAS) is underway to map genomic regions associated with yield traits. Preliminary findings highlight major QTLs on chromosome 2A for grain number, in line with previous studies, and additional associations on 6A and 7B for grain size and weight. All samples have been stored, and ongoing qualitative analyses (e.g., fiber and starch content) aim to support breeding for both yield and nutritional quality.