SAINT PAUL, MINNESOTA
University of Minnesota and USDA-ARS

Development of the first fertile plants with an addition of the whole maize chromosome 10 to the oat genome

— Kynast, RG; Okagaki, RJ; Galatowitsch, MW; Huettl, PA; Jacobs, MS; Stec, AO; Walsh, MD; Cabral, CB; Odland, WE; Rines, HW; Phillips, RL

The genome of maize, Zea mays L., has been dissected into 10 entities, reflecting the addition of individual maize chromosomes to hexaploid oat, Avena sativa L. A complete set of oat-maize chromosome additions is available and can be used to map markers to chromosome and analyze the expression of individual genes and their specific interaction with an alien background (Kynast et al. 2002: Funct. Integr. Genomics 2, 60–69).

More than 50 fertile lines are available with monosomic and/or disomic addition of individual chromosomes of different maize lines in different oat cultivars serving as chromosome recipients; however, maize chromosome 10 has been available as a self-fertile line only as a telocentric derivative for the short arm. Whole chromosome 10 additions were previously sterile (Kynast et al. 2004: Proc. Natl. Acad. Sci. USA 101, 9921–9926). The added maize chromosomes were identified by cytological and molecular means, as described elsewhere (Kynast et al. 2001: Plant Physiol. 125, 1228–1235).

In a recently undertaken series of crosses with maize inbred lines B73 and Mo17 as chromosome donors, one inter-species hybrid (F1-5751-1) tested as a juvenile plantlet (F1-5751-1*) appeared to have retained the whole maize chromosome 10 in addition to the haploid oat complement, based on the positive test with maize chromosome arm 10S-specific SSR marker p-umc1293 and maize chromosome arm 10L-specific SSR marker p-bnlg1839 (Figure 1).Tests of genomic DNAs from flag leaves of the first four tillers (F1-5751-1a, F1-5751-1b, F1-5751-1c, and F1-5751-1d) verified the presence of maize chromosome 10 in the plant. The plant was a descendent of the cross Starter × Mo17 and showed limited fertility after self-pollination (Table 1). The panicle (231 spikelets) from the a-tiller had 2 seeds, of which one seed did not germinate. The panicle (190 spikelets) from the b-tiller had one seed. The panicle (201 spikelets) of the c-tiller had six seeds, of which one did not germinate. The panicle (194 spikelets) of the d-tiller was sterile.

We observed transmission of the maize chromosome in the seven F2-offspring. Eight markers were selected which were distributed across the length of the chromosome: umc1380, umc1576, umc2034, gcsh1, umc1272, umc1084, umc2021, and csu48. PCR assays detected these sequences in the F2-offspring, indicating that the maize chromosome is intact (Figure 1). We will assess stability and transmission in subsequent generations.

The line was given the designation OMAd10.23 in accordance with the proposed nomenclature for oat-maize chromosome addition lines (Kynast et al. 2001: Maize Genet. Coop. Newsl. 75, 54–55).

This material is based upon work supported by the National Science Foundation under Grant No. 0110134.

Table 1. Seed set of a new F1 (oat maize) whole maize chromosome 10 addition

*Two seeds (F2-K1179a-2 and F2-K1179c-4) did not germinate

Figure 1. Gel electrophoreses of PCR products from gDNAs of the seven offspring F2-K1179 by use of primers for four short arm-specific and four long arm-specific markers genetically mapped to maize chromosome 10 from the IBM2 2004 Map (MaizeGDB). Oat-maize addition line 10.01 is a vegetative F1.

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