Reciprocal regulation of Ca²+-activated outward K+ channels of Pyrus pyrifolia pollen by heme and carbon monoxide.
• The regulation of plant potassium (K+) channels has been extensively studied in various systems. However, the mechanism of their regulation in the pollen tube is unclear. • In this study, the effects of heme and carbon monoxide (CO) on the outward K+ (K+(out)) channel in pear (Pyrus pyrifolia) pollen tube protoplasts were characterized using a patch-clamp technique. • Heme (1 μM) decreased the probability of K+(out) channel opening without affecting the unitary conductance, but this inhibition disappeared when heme was co-applied with 10 μM intracellular free Ca²+. Conversely, exposure to heme in the presence of NADPH increased channel activity. However, with tin protoporphyrin IX treatment, which inhibits hemeoxygenase activity, the inhibition of the K+(out) channel by heme occurred even in the presence of NADPH. CO, a product of heme catabolism by hemeoxygenase, activates the K+(out) channel in pollen tube protoplasts in a dose-dependent manner. The current induced by CO was inhibited by the K+ channel inhibitor tetraethylammonium. • These data indicate a role of heme and CO in reciprocal regulation of the K+(out) channel in pear pollen tubes.
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Ju-You
JY
Wu
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Hai-Yong
HY
Qu
College of Life Sciences, HeBei Normal University, Shi Jia Zhuang 050016, China.
Zhong-Lin
ZL
Shang
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Shu-Tian
ST
Tao
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Guo-Hua
GH
Xu
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Jun
J
Wu
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Hua-Qing
HQ
Wu
College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Shao-Ling
SL
Zhang
D002248:Carbon Monoxide / Q000494:pharmacology*; D018525:Germination / Q000187:drug effects; D006418:Heme / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects*; D009249:NADP / Q000494:pharmacology; D011058:Pollen / Q000187:drug effects / Q000378:metabolism*; D053205:Pollen Tube / Q000187:drug effects / Q000254:growth & development; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism*; D011523:Protoplasts / Q000187:drug effects / Q000378:metabolism; D031989:Pyrus / Q000187:drug effects / Q000378:metabolism*
D024681:Potassium Channels, Calcium-Activated; D006418:Heme; D009249:NADP; D002248:Carbon Monoxide