Analysis of Growth Response and Gene Expression by Waterlogging Stress on B73 Maize

Maize is thought to be an alternative crop to rice in paddy fields for efficient field management and maintenance of rice production at appropriate levels in Korea. Thus efforts to breed waterlogging-tolerant maize cultivars have been ongoing. However, molecular studies related to waterlogging tolerance are limited for developing molecular markers to select waterlogging tolerant maize varieties. In this study, we examined molecular biological changes of B73 in the V3 stage after immersion treatment for 7 days. Overall growth of maize was lower in treated samples compared to non-immersed control samples. The length of leaf and root decreased by 21.3% and 50.6%, respectively and the weight of root reduced by 21.6%. Soil plant analysis development (SPAD) value and chlorophyll content of leaf also decreased by 55.7% and 35.3%, respectively. Reactive oxygen species (ROS) content of root increased by 46.5% at 2 hours in immersion treatment. In addition, immersed roots were 2.5-fold thickened with additional aerenchyma formation in the cortex. In order to identify the causes of these changes, we performed a microarray and found increased expression of genes, such as WIP1, PMIP2, EXPA1, TPS1, and MAS1, in immersed samples. These differentially expressed genes and expression of previously reported genes, including ALDH2, Wusl1032, UP-1, UP-2, and CAT2 were further confirmed with qRT-PCR. Here, we report 7 differentially expressed genes after immersing treatment, which may be utilized as useful resources for breeding waterloggingtolerant maize.