GrainGenes

II. 12. Allele tests and chromosome location of two male sterile mutants in Ingrid.

R. T. Ramage and J. E. Flora. Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721, U.S.A. "R"

Two male sterile mutants were found during a search for spontaneous mutants and chromosome aberrations in the cultivar Ingrid. Both of these mutants are monofactorial recessives and were assigned the allele designations msg,,ed and msg,,ee.

The mutants were crossed with a translocation tester set. They were also crossed with the BTT 27d msg2 a369 in a search for male sterile genes located on chromosome 2.

All of the F1 plants from crosses of msg,,ed with the BTT were male sterile indicating that msg,,ed is allelic to msg2. It is now designated msg2ed. All of the F1 plants from crosses of msg,,ee with the BTT were male fertile.

The msg2 locus is near the centromere of chromosome 2, therefore, only those crosses of msg2ed with translocations involving chromosome 2 were grown in F3. Data from those crosses are given below:

No crossovers were observed in either the normal or semisterile F3 rows. As an additional check for allelism with msg2, plants of the genotype msg2ed msg2ed were crossed with plants of the genotype Msg2ax msg2ax. The F1 of this cross contained 21 male fertile and 26 male sterile plants confirming the designation msg2ed.

F3 rows were grown from all of the crosses of msg,,ee with the translocation tester set. Data from the crosses are given below:

Very tight linkage is evident between msg,,ee and the translocation break-points of Tl-2d and Tl-5e. This should place the msg,,ee locus on chromosome 1, probably fairly close to the centromere.

Plants of the genotype msg,,ee msg,,ee were crossed with plants that were heterozygous for other male sterile alleles, including all those known to be located on chromosome 1 and those that have not yet been assigned to a chromosome. Crosses were not made with alleles that have been assigned to a chromosome other than chromosome 1.

Data from these allele crosses are given

These data indicate that msg,,ee is not allelic to any of these 15 loci which include all of those that have been located on chromosome 1. The two male sterile plants observed from crosses with Msg33 msg33 could have been either sibs or selfs as one head used in the allele crosses was not bagged prior to crossing and msg33 msg33 plants are known to set an occasional selfed seed.

To complete the allele tests, we need crosses of msg,,ee with msg25, msg26, msg27, msg29 and msg31. These crosses are not being made.

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