Effect of individual Sumai 3 chromosomes on resistance to scab spread within spikes and deoxynivalenol accumulation within kernels in wheat.

Two sets of substitution lines were developed by crossing individual monosomic lines of Chinese Spring (recipient) with scab (Fusarium graminearum) resistant cultivar Sumai 3 (donor) and then using the monosomics as the recurrent male parent for four backcrosses (without selfing after each backcross). The disomic substitution lines were separated from selfed BC4F2 plants. Chromosome specific SSR markers were analyzed for polymorphism between Sumai 3 and Chinese Spring. Polymorphic markers were used to identify substitution lines for specific chromosomes. Based on the specific SSR markers, chromosome substitutions occurred in thirty-six lines, and six lines segregated alleles from the two parents or were homozygous for the allele from Chinese Spring. These substitution lines were used to evaluate Type II (spread within the head) and Type V (deoxynivalenol accumulation within kernels) scab resistance. The objective was to use the substitution lines to evaluate the effect of individual chromosomes of Sumai 3 on Type 11 and Type V scab resistance in the greenhouse. Significant differences in Type II scab resistance and deoxynivalenol (DON) levels among different Chinese Spring (Sumai 3) substitution lines were detected. Positive chromosome substitution effects on Type II scab resistance were found on chromosomes 2B, 3B. 6B, and 7A from Sumai 3. Chromosomes 3B and 7A also reduced DON accumulation within the kernels, while chromosomes IB, 2D, and 4D from Sumai 3 increased DON concentration. Chromosome 7A from Sumai 3 had the largest effect on resistance to scab spread and DON accumulation. Additional research is in progress on the scab resistance conferred by chromosome 7A.