Development of salinity-tolerant wheat recombinant lines from a wheat disomic addition line carrying a Thinopyrum junceum chromosome

Three Triticum aestivum L. x Thinopyrum junceum (L.) A. Love partial amphidiploids (2n = 8x = 56; 21" ABD + 7" E-b/E-e) and 11 derived disomic addition lines (2n = 44) were screened for salt tolerance in hydroponic solutions. One addition line (AJDAj5, 21" ABD + 1" E-b) had salt tolerance comparable to that in partial amphidiploids. It was crossed to a wheat line having the Ph-I allele from Aegilops speltoides Tausch to induce homoeologous pairing. F-2 plants were subjected to salt screening and advanced to 30 F-3 families, which were screened again. Four F-3 lines were more tolerant than AJDAj5 when screened in a final electrical conductivity of 42 dS/m. Because one of the four lines was sterile, only three lines were further verified for their salinity tolerance and were cytologically and molecularly analyzed. These lines were translocation lines with 42 chromosomes having tiny fluorescent hybridization signals detected at interstitial positions of less condensed chromosomes using the genomic in situ hybridization technique. Amplified fragment length polymorphism analyses revealed the presence of very few (ca. 4%) putative markers specific to the E-b-chromosome addition line. These lines also had from 2% to 14% of markers specific to the Ph inhibitor line and a few new AFLP markers that were not found in the two parental lines and the common wheat background, cv. Chinese Spring. Two recombinant lines were more salt tolerant than either parent, while the third one was as tolerant as either parent, which was more tolerant than Chinese Spring. The former two lines are valuable germplasm for breeding salt-tolerant wheat cultivars.