Relative haploid induction and fertility efficiency in hexaploid, tetraploid and wheat × rye derivatives following Zea mays- and Imperata cylindrica-mediated chromosome elimination approach

Context In plant breeding, rapid development of homozygous lines is vital for accelerating varietal improvement. Doubled haploid (DH) breeding enables the production of fully homozygous lines in a single generation, whereas the effect of uniparental elimination following inter-generic hybridisation on seed fertility remains unclear. Aims To determine reliable and efficient approach of DH breeding by using a diverse panel of wheat types with Imperata cylindrica and maize as pollen sources and to estimate the relative fertility of the first-generation DHs. Methods Inter-generic hybridisation using pollens of composite variety of maize and I. cylindrica with 16 hexaploids, seven tetraploids and three wheat × rye derivatives (BC1F3) was undertaken and various haploid and DH induction parameters were evaluated. General combining ability (GCA) analysis was conducted to identify superior lines and the DHs developed were assessed for seed setting frequency. Key results Significant differences were found for most haploid induction parameters. GCA tests identified hexaploid genotypes (DH 86, HS 295, HPW 155) and tetraploid genotypes (A-9-30-1, PDW 314, PDW 191) as superior combiners, and I. cylindrica emerged as the most effective pollen source, especially in hexaploid wheat genotypes. Nineteen new first-generation DHs were developed with seed setting at par to their parental variety. Conclusions I. cylindrica was shown to be a more effective pollen source than was maize for DH production in wheat and the new DHs developed were true to type. Implications DH breeding can accelerate wheat breeding programs by producing homozygous lines efficiently, while retaining fertility levels similar to those of their parent lines.