QTL mapping of root aerenchyma formation in seedlings of a maize x rare teosinte "Zea nicaraguensis" cross

Using a 141 F-2 population generated from maize inbred B64 x teosinte Zea nicaraguensis cross, quantitative trait loci (QTLs) controlling aerenchyma formation in roots under non-flooding drained soil conditions were identified. Seedlings of Z. nicaraguensis formed clear aerenchyma in the cortex of adventitious roots in non-flooding conditions, whereas the maize inbred line B64 did not. In the F-2 population, the capacity to develop aerenchyma exhibited wide and continuous variation, suggesting the trait was controlled by multiple genes. A linkage map was developed using 85 SSR markers, covering 1,224 cM across all ten chromosomes. Composite interval mapping analysis revealed that four QTLs for aerenchyma formation under non-flooding conditions were located to two regions of chromosome 1 (identified as Qaer1.02-3 and Qaer1.07), chromosome 5 (Qaer5.09) and chromosome 8 (Qaer8.06-7), and these explained 46.5% of the total phenotypic variance. The multiple interval mapping approach identified additional QTLs on chromosomes 1 (Qaer1.01) and 5 (Qaer5.01). Using these results, it may be possible to use SSR markers linked to aerenchyma formation in a marker assisted selection approach to introduce aerenchyma formation in drained soil conditions into maize for the eventual development of flooding tolerant maize hybrids.