A maize chromosome 3 addition line of oat exhibits expression of the maizehomeobox gene liguleless3 and alteration of cell fates

Maize chromosome addition lines of oat offer the opportunity to study maize gene expression in oat and the resulting phenotypes. Morphological examina tion of a maize chromosome 3 addition line of oat showed that this line exh ibited several morphological abnormalities including a blade-to-sheath tran sformation at the midrib region of the leaf, a hook-shaped panicle, and abn ormal outgrowth of aerial axillary buds. Dominant mutations in the maize li guleless3 (lg3) homeobox gene result in a blade (distal)-to-sheath (proxima l) transformation at the midrib region of the leaf. Ectopic expression of t he dominant mutant Lg3 allele is believed to cause the phenotype. Therefore , we suspected that the maize lg3 gene, which is located on maize chromosom e 3, was involved in the phenotypes observed in the maize chromosome 3 addi tion line of oat. Genetic analyses of an oat BC1F2 family segregating for m aize chromosome 3 showed that the presence of a stable maize chromosome 3 w as required for the expression of these cell fate abnormalities. RNA expres sion analysis of leaf sheath tissue from oat plants carrying maize chromoso me 3 demonstrated that maize LG3 transcripts accumulated in oat, indicating that this expression is associated with the blade-to-sheath transformation , hook-shaped panicle and outgrowth of aerial axillary bud phenotypes. Our results demonstrate that the maize chromosome addition lines of oat are use ful genetic stocks to study expression of maize genes in oat.