High segregation distortion in maize B73 x teosinte crosses.

Two genetic linkage maps of cultivated maize inbred lines and teosinte species were constructed. One population comprised 81 F(2) individuals derived from a cross between maize inbred line B73 and Zea mays ssp parviglumis, while the second consisted of 63 backcross individuals from a cross of maize inbred line B73 with Z. mays ssp diploperennis. In the B73 x Z. mays ssp parviglumis F(2) population, 172 simple sequence repeat (SSR) markers were mapped to 10 chromosomes, which covered 2210.8 cM. In the B73 x Z. mays ssp diploperennis backcross population, 258 SSR markers were mapped to 10 chromosomes, covering 1357.7 cM. Comparison of the two maps revealed that the total map length of Z. mays ssp diploperennis covers 1357.7 cM, which is about 61.4% of that of Z. mays ssp parviglumis (2210.8 cM). Extensive segregation distortion regions were found on chromosomes 1, 2, 3, 5, 6, 7, and 10 in the B73 x Z. mays ssp parviglumis F(2) population and on chromosomes 1-5 and 8-10 in the B73 x Z. mays ssp parviglumis backcross population. Segregation distortion analysis confirmed that the segregation distortion ratio in the interspecific population B73 x Z. mays ssp diploperennis was higher than in B73 x Z. mays ssp parviglumis. We found that the recombination distances are highly variable in these genetic crosses between cultivated and wild species of maize.