Genotype analysis of the wheat semidwarf R ht‐ B 1b and R ht‐ D 1b ancestral lineage

In wheat, semidwarfism resulting from reduced height ( Rht )‐ B1b and Rht‐D1b was integral to the ‘green revolution’. The principal donors of these alleles are ‘ N orin 10’, ‘ S eu S eun 27’ and ‘ S uwon 92’ that, according to historical records, inherited semidwarfism from the J apanese landrace ‘ D aruma’. The objective of this study was to examine the origins of R ht‐ B 1b and R ht‐ D 1b by growing multiple seed bank sources of cultivars comprising the historical pedigrees of the principal donor lines and scoring R ht‐1 genotype and plant height. This revealed that ‘ N orin 10’ and ‘ S uwon 92’ sources contained R ht‐ B 1b and R ht‐ D 1b , but the ‘ S eu S eun 27’ source did not contain a semidwarf allele. Neither R ht‐ B 1b nor R ht‐ D 1b could be definitively traced back to ‘ D aruma’, and both ‘ D aruma’ sources contained only R ht‐ B 1b . However, ‘ D aruma’ remains the most likely donor of R ht‐ B 1b and R ht‐ D 1b . We suggest that the disparity between historical pedigrees and R ht‐1 genotypes occurs because the genetic make‐up of seed bank sources differs from that of the cultivars actually used in the pedigrees. Some evidence also suggests that an alternative R ht‐ D 1b donor may exist.