A Tal-PhI wheat genetic stock facilitates efficient alien introgression

Abstract

The genetic stock Chinese Spring PhI (refer as CS-PhI hereafter) with the Ph I gene (Ph gene inhibitor, introduced from a high-pairing accession of Aegilops speltoides) was crossed as a male parent to a Tai-gu genic male-sterile wheat with the Tal gene and backcrossed once to CS-PhI to develop the Tal-PhI genetic stock. The Tal-PhI stock, CS-PhI as well as Chinese Spring (CS), were test-crossed using Aegilops peregrina (syn. Aegilops variabilis) to test the effectiveness of the Ph I gene inducing homoeologous chromosome pairing in the Tal-PhI stock. At meiotic I(MI) of pollen mother cells (PMCs), the average chromosome pairing of the TC1 testcrosses of TalCSPhIC08–4/Ae. peregrina, TalCSPhIC11–5/Ae. peregrina and CS/Ae. peregrina was 26.81 I + 3.64 II + 0.33 Open image in new window + 0.07 III + 0.01 IV, 24.75 I + 4.58 II + 0.25 Open image in new window + 0.21 III + 0.07 IV and 32.25 I + 1.38 II, respectively. These data indicated that the Ph I gene could promote homoeologous chromosome pairing in the Tai-gu male sterile background. In order to verify the introgression of the chromatin from Ae. speltoides into CS in the three CS-PhI lines, a total of 79 SSR primers located on group-3 chromosomes were used for PCR analysis using the genomic DNA of CS, Ae. speltoides and the three CS-PhI lines. Two markers Xwmc505 -110 and Xwmc674 -160 amplified S genome-specific fragments from Ae. speltoides in lines PhIC04–13 and PhIC11–5, providing molecular evidence for the introgression of Ae. speltoides-specific chromatin in the two lines. Furthermore, some 3D-specifc SSR markers were missing in line PhIC04–13, indicating there might be a deletion of chromosome 3D in this line. In further experiments, a BC1 population was produced from the cross of Tal-PhI/Triticum durum-Dasypyrum villosum amphiploid (AABBVV)//CS-PhI, and the progenies were further screened for chromosome recombination by GISH analysis. A homozygous translocation line T5VS·5VL-5DL was identified from the BC1F2 by genomic in situ hybridization, C-banding and SSR analysis. The results of the present study demonstrate the Tal-PhI is a useful genetic stock for transferring alien genes into common wheat.