Carbon monoxide enhances the chilling tolerance of recalcitrant Baccaurea ramiflora seeds via nitric oxide-mediated glutathione homeostasis.
Both carbon monoxide (CO) and nitric oxide (NO) play fundamental roles in plant responses to environmental stress. Glutathione (GSH) homeostasis through the glutathione-ascorbate cycle regulates the cellular redox status and protects the plant from damage due to reactive oxygen species (ROS) or reactive nitrogen species (RNS). Most recalcitrant seeds are sensitive to chilling stress, but the roles of and cross talk among CO, NO, ROS, and GSH in recalcitrant seeds under low temperature are not well understood. Here, we report that the germination of recalcitrant Baccaurea ramiflora seeds shows sensitivity to chilling stress, but application of exogenous CO or NO markedly increased GSH accumulation, enhanced the activities of antioxidant enzymes involved in the glutathione-ascorbate cycle, decreased the content of H(2)O(2) and RNS, and improved the tolerance of seeds to low-temperature stress. Compared to orthodox seeds such as maize, only transient accumulation of CO and NO was induced and only a moderate increase in GSH was shown in the recalcitrant B. ramiflora seeds. Exogenous CO or NO treatment further increased the GSH accumulation and S-nitrosoglutathione reductase (GSNOR) activity in B. ramiflora seeds under chilling stress. In contrast, suppressing CO or NO generation, removing GSH, or blocking GSNOR activity resulted in increases in ROS and RNS and impaired the germination of CO- or NO-induced seeds under chilling stress. Based on these results, we propose that CO acts as a novel regulator to improve the tolerance of recalcitrant seeds to low temperatures through NO-mediated glutathione homeostasis.
Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
Xue-gui
XG
Bai
Jin-hui
JH
Chen
Xiang-xiang
XX
Kong
Christopher D
CD
Todd
Yong-ping
YP
Yang
Xiang-yang
XY
Hu
De-zhu
DZ
Li
D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D002248:Carbon Monoxide / Q000378:metabolism / Q000494:pharmacology*; D003080:Cold Temperature; D004573:Electrolytes / Q000378:metabolism; D018525:Germination / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000378:metabolism; D019684:Magnoliopsida / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology; D010940:Plant Proteins / Q000378:metabolism; D011309:Preservation, Biological; D026361:Reactive Nitrogen Species / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D013312:Stress, Physiological
D004573:Electrolytes; D010940:Plant Proteins; D026361:Reactive Nitrogen Species; D009569:Nitric Oxide; D002248:Carbon Monoxide; D006861:Hydrogen Peroxide; D006419:Heme Oxygenase (Decyclizing); D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent; D005978:Glutathione