Suppression of Phytoglobin Proteins (Pgb) increase corn seedling tolerance to Goss’s bacterial wilt infection
Date
2018
Authors
Owusu, Veronica
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The effects of suppression of the Zea maize Phytoglobin 1 (ZmPgb1) on plant response to infection with Clavibacter nebraskensis (isolate Cmn14-5-1), were evaluated by measuring leaf lesion and physiological events associated with biotic stress. Relative to wild type (WT), suppression of ZmPgb1 reduced the size of leaf lesions and elevated the expression of genes involved in ethylene synthesis and response, as well as those contributing to the generation of reactive oxygen species (ROS). The same plants displayed a more pronounced accumulation of ROS and programmed cell death (PCD) in proximity of the inoculation site. Similar transcriptional responses were also observed in cultured maize cells infected with isolate Cmn 14-5-1. Pharmacological treatments were performed in culture to alter the levels of NO, and/or ethylene (ETH). An experimental increment in NO with the NO donor sodium nitroprusside (SNP), or ethylene with the ethylene precursor ethephon (ETH), increased the production of ROS and elevated the number of cells undergoing PCD in WT cells. An opposite response was observed in cells suppressing ZmPgb1 when the level of NO or ethylene was reduced with the respective utilization of 4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) or aminooxyacetic acid (AOA). Collectively these findings suggest that suppression of ZmPgb1 enhances tolerance to Clavibacter nebraskensis through a mechanism initiated by the accumulation of NO, mediated by ethylene, and culminating with the production of ROS and the execution of PCD.
Description
Keywords
Goss’s wilt, reactive oxygen species, ethylene, maize, phytoglobin, hypersensitivity response, programmed cell death