Revealing the roles of GORK channels and NADPH oxidase in acclimation to hypoxia in Arabidopsis.
Regulation of root cell K+ is essential for acclimation to low oxygen stress. The potential roles of GORK (depolarization-activated guard cell outward-rectifying potassium) channels and RBOHD (respiratory burst oxidase homologue D) in plant adaptive responses to hypoxia were investigated in the context of tissue specificity (epidermis versus stele; elongation versus mature zone) in roots of Arabidopsis. The expression of GORK and RBOHD was down-regulated by 2- to 3-fold within 1 h and 24 h of hypoxia treatment in Arabidopsis wild-type (WT) roots. Interestingly, a loss of the functional GORK channel resulted in a waterlogging-tolerant phenotype, while rbohD knockout was sensitive to waterlogging. To understand their functions under hypoxia stress, we studied K+, Ca2+, and reactive oxygen species (ROS) distribution in various root cell types. gork1-1 plants had better K+ retention ability in both the elongation and mature zone compared with the WT and rbohD under hypoxia. Hypoxia induced a Ca2+ increase in each cell type after 72 h, and the increase was much less pronounced in rbohD than in the WT. In most tissues except the elongation zone in rbohD, the H2O2 concentration had decreased after 1 h of hypoxia, but then increased significantly after 24 h of hypoxia in each zone and tissue, further suggesting that RBOHD may shape hypoxia-specific Ca2+ signatures via the modulation of apoplastic H2O2 production. Taken together, our data suggest that plants lacking functional GORK channels are more capable of retaining K+ for their better performance under hypoxia, and that RBOHD is crucial in hypoxia-induced Ca2+ signalling for stress sensing and acclimation mechanism.
School of Land and Food, University of Tasmania, Hobart, Tasmania 7001, Australia.
Feifei
F
Wang
School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia.
Zhong-Hua
ZH
Chen
School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia.|School of Light Industry Engineering, Guizhou Institute of Technology, Guiyang 550003, China.
Xiaohui
X
Liu
School of Plant Biology and Institute of Agriculture, The University of Western Australia, Crawley, WA, 6009, Australia.
Timothy D
TD
Colmer
School of Land and Food, University of Tasmania, Hobart, Tasmania 7001, Australia.
Lana
L
Shabala
School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia.
Anya
A
Salih
School of Land and Food, University of Tasmania, Hobart, Tasmania 7001, Australia.
Meixue
M
Zhou
School of Land and Food, University of Tasmania, Hobart, Tasmania 7001, Australia.
Sergey
S
Shabala
D000064:Acclimatization; D000693:Anaerobiosis; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D019255:NADPH Oxidases / Q000235:genetics* / Q000378:metabolism; D009928:Organ Specificity; D018517:Plant Roots / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism
D029681:Arabidopsis Proteins; C584663:GORK protein, Arabidopsis; D015221:Potassium Channels; C568857:AT5G47910 protein, Arabidopsis; D019255:NADPH Oxidases; D011188:Potassium
Calcium; H2O2; epidermis; fluorescence dyes; homeostasis; potassium; reactive oxygen species; signalling; stele; superoxide