The effects of low energy nitrogen ion implantation on Ca2+ concentration and membrane potential of illy (Mum davidii Duch) pollen cell have been studied. The results showed that the Ca2+ concentration was increased when pollen grain was implanted by nitrogen ion with energy 100 keV and dose 1013 ions/cm2. However, the increase of Ca2+ concentration was partly inhibited by the addition of Ca2+ channel inhibitor depending on dose. And nitrogen ion implantation caused depolarization of pollen cell membrane potential. In other words, membrane potential was increased, but the effect decreased by adding Ca2+ channel inhibitor. However, it was still significantly higher than the membrane potential of control cells. It was indicated that the depolarization of cell membrane potential opened the calcium channel on the membrane that caused the increasing of intracel-lular calcium concentration. This might be an earlier step of the effect of low energy nitrogen ion implantation on pollen germination.
HUANG Zhonglian, JING Yanping, ZHU Guoli, LU Ting, ZHOU Hongyu & REN Haiyun1. Key Laboratory of Cell Proliferation and Regulation Biology of the Ministry of Education, Beijing Normal University, Beijing 100875, China
The relationship between Ca 2+ and ethylene response was investigated through analyzing the effect of Ca 2+ on the response to ethylene in etiolated tomato (Lycopersicon esculentum Mill cv. Lichun) seedling grown in darkness. When the etiolated tomato seedlings were treated with different concentrations of Ca 2+, the 'triple response' phenotype, ethylene production, the expression of ethylene receptor gene NEVER-RIPE (NR) and the content of cytosolic CaM were determined. With the concentration of Ca 2+ in the culture medium increasing from 0 mmol/L to 3.8 mmol/L, the 'triple response' phenotype of etiolated tomato seedling was correspondingly strengthened; meanwhile the ethylene production, the amount of NR gene expression and the concentration of CaM increased respectively. However, when the concentration of Ca 2+ was increased from 3.8 mmol/L to 10 mmol/L, the phenotype of 'triple response', ethylene production, NR gene expression, and the CaM content didn't increase further, but decreased consequently. The results indicated that the effect of Ca 2+ on the ethylene triple response in etiolated tomato seedling was relevant to ethylene biosynthesis and ethylene receptor gene expression which were influenced by applied Ca 2+, and these effects might be mediated through the change of CaM concentration in plant cell.
