yellow mosaic virus (ZYMV). Viral resistance is recessive. The hierarchical orde

Question

yellow mosaic virus (ZYMV). Viral resistance is recessive. The hierarchical order of dominance at the ZYM locus is ZYM (100% susceptible) > zyml (partially resistant). zym2 (completely resistant). The zym2 allele demonstrates resistance to several other virus as well, making it highly sought after in breeding programs. 3. Kabelka et al. (1997) discovered multiple alleles bestowing differential degrees of resistance to the zucchini A second discovered locus (M), confers resistance to the Moroccan Watermelon Mosaic Virus (MWMV) where M (100% susceptible) is dominant over m (100% resistant) past crosses, she has isolated two hybrids. Hybrid 1 has the genotypes zym1 zym2 and Mm. Hybrid 2 has the genotypes ZYM zym2 and Mm. A breeder wants to create a hybrid fully resistant to all possible virus to both genes simultaneously. From a) What genotype would be fully resistant to all possible virus? (5 points) b) What c) What phenotypic ratio o t phenotypic ratio of the offspring are expected to be fully resistant to all possible virus? (S points) f the offspring are expected to be at least partially resistant to all possible virus? HINT-That statement could also be reworded to be partially or fully resistant. (5 points) She is surprised to get very different results. From 200 plants, she gets the following data and concludes gene linkage between the loci. Even though multiple alleles are present, they are at one locus, and she knows she can simplify her data to non-recombinants and recombinants and do a standard 2-point calculation. ZYMV susceptible and MWMV susceptible ZYMV susceptible and MWMV resistant ZYMV partially resistant and MWMV susceptible ZyMV partially resistant and MWMV resistant YMV fully resistant and MwMV susceptible ZYMV fully resistant and MWMV resistant 49 48 49 48 c) What is the distance between the ZYM and M genes in her desired hybrid? (5 points)

Explanation / Answer

3) ZYM = 100% SUCCEPTIBLE

zym1=partially resistant

zym2 = completely resistant

Second locus

M = 100% SUCCEPTIBLE and DOMINANT over m

m= 100% resistant

After breeding the hybrids created having genotype (hybrid 1) zym1 zym2 Mm

hybrid 2 genotype ZYM, zym2 ,Mm

a) genotype which will be fully resistant to all possible viruses is : zym2 ,zym1, mm

b) phenotypic ratio will be 1/9= 0.9

c) Recombinants total= 1+1= 2

single crossovers= 48+49= 97

single crossovers= 49+48= 97

recombinant freq= 2/ 194 = 0.010= 1%

1% recombination= 1 map unit

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