The invention discloses a method by adopting
molecular marker-assisted backcross to improve gibberellic
disease expansion resistance of wheat. A recombinant inbred line family carrying expansion-resistant quantitative trait loci (QTL) is adopted as a donor, a line which has excellent comprehensive character but is infected by gibberellic diseases is adopted as a
receptor, and the donor is hybridized and backcrossed with the
receptor. Two side markers which are closely interlocked with a target QTL are utilized for selecting a foreground in each backcross generation, 150 pairs of simple sequence repeats (SSR) markers which are distributed in an entire wheat
genome are utilized for selecting a background respectively for a
single plant carrying the target QTL, and the
single plant with the highest background repeated rate is selected for the next generation of backcross. A near-isogenic line with the resistance being obviously improved and other characters being basically consistent with that of a recurrent parent is obtained after being continuously backcrossed for
three generations and then being inbred for two generations. A target
single plant can be obtained by extracting deoxyribonucleic acid (
DNA) of
seedling leaves of backcrossed generations and analyzing a marker
genotype, so that the problems in phenotypic selection that the gibberellic
disease resistance is susceptible to an environmental condition and a resistance
phenotype can be determined only in a flowering period can be effectively solved; and meanwhile, the
population size can be reduced, the breeding cost can be reduced, and the gibberellic
disease expansion resistance of the wheat line can be rapidly and effectively improved.