Abstract
Flooding limits biomass production in agriculture. Leguminous plants, important agricultural crops, use atmospheric dinitrogen gas as nitrogen nutrition by symbiotic nitrogen fixation with rhizobia, but this root-nodule symbiosis is sometimes broken down by flooding of the root system. In this study, we analyzed the effect of flooding on the symbiotic system of transgenic Lotus japonicus lines which overexpressed class 1 phytoglobin (Glb1) of L. japonicus (LjGlb1-1) or ectopically expressed that of Alnus firma (AfGlb1). In the roots of wild-type plants, flooding increased nitric oxide (NO) level and expression of senescence-related genes and decreased nitrogenase activity; in the roots of transgenic lines, these effects were absent or less pronounced. The decrease of chlorophyll content in leaves and the increase of reactive oxygen species (ROS) in roots and leaves caused by flooding were also suppressed in these lines. These results suggest that increased levels of Glb1 help maintain nodule symbiosis under flooding by scavenging NO and controlling ROS.
Highlights
Flooding often reduces crop growth and yield, causing serious problems for farmers
We examined the tolerance of the nodule symbiosis to flooding in two transgenic
Our results suggest that Glb1 overexpression improves nodule symbiosis by controlling nitric oxide (NO) and reactive oxygen species (ROS)
Summary
Plant growth is hampered by flooding because it exposes plants to hypoxia, which inhibits aerobic respiration and photosynthesis, reducing ATP production. Hypoxia inhibits photosynthesis by inducing production of reactive oxygen species (ROS), which damage the chloroplast membrane and decrease the photosynthetic potential [1,2]. Excess ROS lead to lipid peroxidation and alterations in lipid composition, electrolyte leakage, and cell death [3,4,5]. Another reactive molecule, nitric oxide (NO), is produced in plants in response to biotic and abiotic stresses, including hypoxia [6,7,8,9]. Excess NO is toxic and inhibits plant growth; plants regulate NO levels by producing plant hemoglobin (phytoglobin, Glb) [12,13]
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.
