A modified chromosome 6

A "modified" chromosome 6 ("MO 6") has been recovered from Tripsacum dactyloides-introgressed "recovered maize" material originally obtained from J. M. J. deWet, U. of Illinois-Urbana, as (Tr75- X -155) selfed. The modification is in the short arm and appears to be a maize-Tripsacum translocation. From pachytene analysis, "MO 6" appears to have gained chromosomal material as well as a medium sized terminal knob. The break appears to be in the terminal portion of the 6S satellite. When "MO 6" is in the heterozygous state, bivalents are commonly observed at diakinesis. At pachytene, the translocation is not easily detected. "MO 6" is most readily seen in root tip mitosis. A comparison of the "MO 6" to the normal 6, at mitotic metaphase, is sketched below.


"MO 6" is both male and female transmissible and is not accompanied by any detectable sterility. A backcrossing program is presently underway to move the chromosome into B73, M020W, KYS, W23, and M017 backgrounds. Further cytological analysis is also being conducted.

B. Kindiger and S. A. Modena

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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