Introgressing root aerenchyma into maize

Root aerenchyma play a significant role in alleviating the effects of low o xygen environments through providing an open passage for oxygen diffusion i nside roots. In Zen mays L, aerenchyma are usually not present but may form in response to environmental stress. Our research indicated that plants of Tripsacum dactyloides L. (eastern gamagrass) and Zen luxurians L. (teosint e) possess well-formed root aerenchyma, even in well-aerated environments. The ability of these species to constitutively form aerenchyma may enhance their competitive ability to grow in wet or compacted soils. Introgressing constitutive aerenchyma into maize may similarly enhance its ability to per form in these environments. Our objective was to investigate the possibilit y of introgressing constitutive root aerenchyma into maize from related spe cies that have constitutive aerenchyma. Hybrid plants from crosses between Z. mays and T. dactyloides and between Z. luxurians and Z. mays were examin ed for the presence or absence of root aerenchyma in a well-aerated environ ment. In Z. mays X T. dactyloides backcross progeny variations in root aere nchyma formation were observed. The genome constitutions of the backcross p rogeny were not stable and the genomes tended to lose Tripsacum chromosomes which allowed an examination of backcross progeny with a varying number of T. dactyloides chromosomes. From this analysis, Ne concluded that constitu tive aerenchyma formation is controlled by more than one locus, but that at least one major controlling locus is associated with the short arm of Trip sacum chromosome 16 (Tr16S). We also found that F-1 plants from the Z. luxu rians X Z. mays cross had aerenchyma in well-aerated environments. This cro ss may be especially important in developing maize lines with constitutivel y produced aerenchyma because Z. luxurians is much more closely related to Z. mays than T. dactyloides.