Transfer of the ph1b gene of ‘Chinese Spring’ into a common wheat cultivar with excellent traits
In wheat/alien species hybrids, pairing homoeologous (Ph1) suppresses the pairing and recombination of wheat and alien chromosomes. Ph1b has been found to be the most effective allele in inducing meiotic homoeologous pairing/recombination and is widely used in gene introgression from wild Triticeae species into wheat. However, due to the poor agronomic traits of the ‘Chinese Spring’ ph1b (CS ph1b) mutant, which is more susceptible to disease, the application of CS ph1b is limited. In this study, we transferred the ph1b gene from the CS mutant to a commercial cultivar Shumai 126 (SM126), which has excellent agronomic traits, by crossing and continuous backcrossing. The results showed that the ph1b was present in 11 lines in the BC2F2 generation and was transferred to SM126. Further study indicated that seven homozygous ph1b mutant allele lines were identified from the BC2F3 generation. Two of these lines, SM126ph1b line 1 and 24, are homozygous at loci encoding high molecular weight glutenin subunits (HMW-GS) and the Wx protein, and the line 24 possesses the excellent agronomic traits of SM126. The results of meiotic metaphase I pairing showed that the SM126ph1b pollen mother cells (PMCs) are slightly higher pairing than the level of the original CSph1b stock. A progeny line of wild cross between wheat and Aegilops sharonensis was crossed with CSph1b and line 24 of SM126ph1b, respectively; the results of ND-FISH further proved that SM126ph1b and CSph1b have same effect on inducing homoeologous pairing/recombination, which will facilitate the use of wheat alien chromosome recombinations in wheat improvement.