Development And Identification Of A Triticum Aestivum-Thinopyrum Bessarabicum Chromosome Translocation Line And Analysis On Its Genetic Effect

Thinopyrum bessarabicum (2n= 2x= 14, JJ or EbEb) confers high salinity tolerance and multiple disease resistance and represents an important resource for wheat improvement. Discrimination of seven pairs of Th. bessarabicum chromosomes and development of markers specific for Th. bessarabicum chromosomes, and development and identification of wheat-Th. bessarabicum translocation lines will facilitate its practical utilization in wheat improvement. Using genomic DNA of Th. bessarabicum, rye repetitive DNA clone pScl 19.2 and 45S rDNA as probes, mitotic chromosomes of Th. bessarabicum and eight Chinese Spring-Th. bessarabicum alien chromosome lines involving seven chromosome pairs of Th. bessarabicum, which included DS1J(1B), T2JS-2BS·2BL, DA6JS·2JL, DA3J, DA4J,DS5J(5A), DS6J(6A) and DA7J, were characterized by genome in situ hybridization (GISH)/fluorescent in situ hybridization (FISH). Based on the hybridization sites of these probes, the seven chromosome pairs were unambiguously discriminated in combined with the chromosome arm ratio. Except 2J and 3J, the other five chromosomes of Th. bessarabicum conseved well in wheat background. This study also produced 69 molecular markers specific for the seven chromosome pairs of Th. bessarabicum, which included 6,22,13,2,9,9 and 8 markers positioned on 1J to 7J, respectively. Of them,26 were derived from salinity-induced wheat ESTs.A novel wheat-Th. bessarabicum translocation line T2JS-2BS-2BL which carries a segment of Th. bessarabicum chromosome arm 2JS was identified and further characterized using sequential chromosome C-banding, genomic in situ hybridization (GISH), dual-color fluorescent in situ hybridization (FISH) and DNA markers. The translocation breakpoint was mapped within bin C-2BS1-0.53 of chromosome 2B through marker analysis. Compared to the Chinese Spring (CS) parent and to CS-type lines, the translocation line has more fertile spikes per plant, longer spikes, more grains per spike and higher yield per plant, which suggests that the alien segment carries yield-related genes. However, plants with the translocation are also taller, head later and have lower thousand-kernel weight than CS or CS-type lines. By using markers specific for the barley photoperiod response gene Ppd-H1, it was determined that the late heading date is conferred by a recessive allele located on the 2JS segment. In addition, four co-dominant markers of 2JS and 2BS were identified which can be used for marker-aided screening.