Plant & Animal Genome IX Conference Plant & Animal Genome IX Conference
Workshop: Abiotic Stress
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Drought and low nitrogen responses in maize have been a focus of research at CIMMYT for the past several years. To address the genetics of these responses, a segregating population was developed by crossing a drought tolerant line (Ac7643S5) with a susceptible line (Ac7729/TZSRWS5). The segregating population was used as the basis for the genetic dissection of several traits related to maize performance under drought, including morphological parameters and yield components. The genetic dissection was performed at two different inbreeding levels (F2;3 and F6), and under different water regimes applied before and during flowering time. In addition to the morphological traits measured on the F3 material, the F6 lines were measured for physiological parameters such as relative water content, osmotic adjustment, root conductivity, and ABA content. The QTLs identified in the F3 families have been published and the results obtained on the F6 families will be presented. Changes in QTL identified at F3 versus F6 levels for some target traits will also be reviewed and discussed. To verify the correlation observed by breeders between drought tolerance and better performance under low N conditions, the F3 families segregating for drought were evaluated under low N environments for the same morphological traits during two subsequent cycles. Various significant QTLs were identified for the target traits, several of them being identified at the same genomic location as under water-limited conditions, especially anthesis-silking interval and ears per plant. Finally, our efforts to identify the specific genes involved at these QTL will be discussed.