Molecular and phenotypic evaluation of durum wheat germplasm for hybrid production

The present study aims at generating the basic knowledge of hybrid technology and examines the magnitude of heterosis for yield through evaluation of eight parents along with 28 F1 hybrids and 25 F1 and 10 parents. The hybrids along with their parents were evaluated in the field-experiment carried out in Bologna, precision phenotyping platform at different levels of water stress and in near-field condition via a basket method to assess yield and root traits. The F1 hybrids were evaluated based on mid and best parent values as well as general and specific combining ability effects. The results showed >20% of mid parent heterosis, indicating the scope for exploitation of heterosis in durum wheat. Valnova x Miki was the best hybrid combination in both experiments followed by Karim x Valnova and Karim x Morocco. Based on the WSTI, three F1 hybrids (Valnova x Miki, Iride x Miki and Svevo x Miki) and one parent (Svevo) were identified as drought tolerant. These results suggest that hybrids do better under water stress but specific hybrid combinations need to be developed to realize higher performance under drought prone environments. To understand the genetic control of flowering time, 384 durum lines were assessed in 13 environments to determine five pheno-environments. Genotyping was conducted with 35K Axiom array to generate 7,740 polymorphic SNPs. In total, 47 significant QTLs were identified for flowering time consistently across the environments. The candidate gene search indicated seven novel genes, namely PRR7, GRF, SVP, RRP6L1, Hd6, TCP1, and COP1/RGA in addition to a number of already known regulatory photoperiodic genes, PPD-A and PPD-B and vernalization genes VRN1, VRN2 and VRN3. In summary, the results obtained from these experiments indicated sufficient heterosis in durum wheat and helped in physiological and molecular characterization of the best heterotic combinations and flowering time.