Abstract
Waterlogging is a severe abiotic stressor causing significant growth impairment and yield losses in many crops. Maize is highly sensitive to the excess of water, and against the background of climate change there is an urgent need for deeper insights into the mechanisms of crop adaptation to waterlogging. In the present study, changes in maize morphology at the 4–5 leaf stage and the expression of three candidate genes for flooding tolerance in plants subjected to six continuous days of waterlogging were recorded in 19 commercial hybrids and in the inbred line B73, with the aim of investigating the current variability in cultivated hybrids and identifying useful morphological and molecular markers for screening tolerant genotypes. Here it was demonstrated that root parameters (length, area, biomass) were more impaired by waterlogging than shoot parameters (shoot height and biomass). Culm height generally increased in stressed plants (by up to +24% vs. controls), while shoot biomass was significantly reduced in only two hybrids. Root biomass was reduced in all the hybrids, by an average of 30%, and significantly in 7 hybrids, while root length and area were even more severely reduced, by 30–55% vs. controls, depending on the hybrid. The earlier appearance of aerial roots seemed to be associated with greater root injuries. In leaves, the transcript of the PFP enzyme (phosphofructokinase), which is involved in glycolytic reactions, was markedly up-regulated (up to double the values) in half the waterlogged hybrids, but down-regulated in the others. The transcript of CYP81D8 (ROS-related proteins) in waterlogged plants exhibited relevant increases or strong decreases in level, depending on the hybrid. The transcript of the AOX1A gene, coding for a mitochondrial respiratory electron transport chain-related protein, was markedly down-regulated in all the treated hybrids. Expression analysis of these genes under extreme waterlogging only partially correlate with the shoot and root growth impairments observed, and AOX1A seems to be the most informative of them.
Highlights
Both hypoxia and anoxia are severe abiotic stresses that severely limit growth and development in many crops worldwide
When a period of extreme flooding is imposed at the early growth stage of maize, greater growth impairment is detectable in the root than in the shoot
As we found large variability in the responses of shoot traits, and of root traits, to a lesser extent, in the set of commercial hybrids we studied, there is reasonable scope for screening for waterlogging stress tolerance, the growth and yield of mature plants should be verified in further studies
Summary
Both hypoxia and anoxia are severe abiotic stresses that severely limit growth and development in many crops worldwide. Molecular oxygen is a terminal electron acceptor in the mitochondrial electron transport chain (ETC) and in the oxidative phosphorylation process; it enables plants to generate sufficient chemical energy stored as adenosine triphosphate (ATP), which is needed for intracellular physiological and biochemical reactions. An effect of both hypoxia and anoxia is a lack of the electron acceptors that promote anaerobic respiration patterns through the activity of alcohol dehydrogenase (ADHase), the most widely studied enzyme involved in fermentation processes (Liao and Lin, 2001; Ren et al, 2014). This is the process by which flooding impairs plant growth, reduces yields and can even cause plant death
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
