The involvement of nitric oxide in ultraviolet-B-inhibited pollen germination and tube growth of Paulownia tomentosa in vitro.
The role of nitric oxide (NO) in the ultraviolet-B radiation (UV-B)-induced reduction of in vitro pollen germination and tube growth of Paulownia tomentosa Steud. was studied. Results showed that exposure of the pollen to 0.4 and 0.8 W m(-2) UV-B radiation for 2 h resulted in not only the reduction of pollen germination and tube growth but also the enhancement of NO synthase (NOS, EC 1.14.13.39) activity and NO production in pollen grain and tube. Also, exogenous NO donors sodium nitroprusside and S-nitrosoglutathione inhibited both pollen germination and tube growth in a dose-dependence manner. NOS inhibitor N(G)-nitro-l-Arg-methyl eater (l-NAME) and NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) not only largely prevented the NO generation but also partly reversed the UV-B-inhibited pollen germination and tube growth. These results indicate that UV-B radiation inhibits pollen germination and tube growth partly via promoting NO production in pollen grain and tube by a NOS-like enzyme. Additionally, a guanylyl cyclase inhibitor 6-anilino-5,8-quinolinequinone (LY-83583) prevented both the UV-B- and NO donors-inhibited pollen germination and tube growth, suggesting that the NO function is mediated by cyclic guanosine 5'-monophosphate. However, the effects of c-PTIO, l-NAME and LY-83583 on the UV-B-inhibited pollen germination and tube growth were only partial, suggesting that there are NO-independent pathways in UV-B signal networks.
He
Jun-Min
JM
School of Life Sciences, Shaanxi Normal University, Xi'an 710062, People's Republic of China. hejm1965@yahoo.com.cn
Bai
Xiao-Ling
XL
Wang
Rui-Bin
RB
Cao
Bing
B
She
Xiao-Ping
XP
D006152:Cyclic GMP / Q000378:metabolism; D019684:Magnoliopsida / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D011058:Pollen / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D012116:Resins, Plant / Q000378:metabolism; D026422:S-Nitrosoglutathione / Q000494:pharmacology; D014466:Ultraviolet Rays
D020030:Nitric Oxide Donors; D012116:Resins, Plant; D009599:Nitroprusside; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester