Crucial Waterlogging-Responsive Genes and Pathways Revealed by Comparative Physiology and Transcriptome in Tropical and Temperate Maize (Zea mays L.) inbred Lines

摘要

Waterlogging is a hazardous natural occurrence to constrain maize production in the high rainfall area in modern agriculture. Thus, there is need to use maize cultivars with desirable resistance to waterlogging stress to mitigate the threat. In this study, Comparative physiological and transcriptomic analysis of tropical and temperate maize lines was performed to reveal the molecular mechanisms underlying maize tolerance to waterlogging. Physiological parameter analysis showed that the tropical line "Suwan-2" sustained relatively lower peroxidase (POD), superoxide dismutase (SOD), and malondialdehyde (MDA), but higher chlorophyll, soluble carbohydrate, and soluble protein contents, as compared to the temperate line "Cim-3" under waterlogging stress. Chlorophyll fluorescence parameters Fv/Fo and Fv/Fm declined consistently and were significant higher in the tropical maize line than the temperate maize line under waterlogging stress. RNA sequencing experiments yielded 21,348 differentially expressed genes (DEGs). Among these, three sets of waterlogging-responsive DEGs were detected, including 314 specific to "Cim-3", 1186 shared between the two lines subjected to waterlogging stress, and 259 overlapping DEGs between the two lines in control conditions. The gene ontology terms cellular process, metabolic process, plant hormone signal transduction, and catalytic activity were highly enriched in the tropical maize line "Suwan-2". Crucial waterlogging-responsive genes in "Suwan-2" were related to transcription factor modulation, cellular redox homeostasis maintenance, plant hormone biosynthesis regulation, and metabolic process. These findings offer insight into the mechanisms underlying the waterlogging tolerance of tropical maize.