Ethylene In The Mung Bean Occurrence Of Adventitious Roots And Its Relationship With NO

Ethylene, as a gaseous phytohormone, plays an important role in plant life. Ethylene regulates a variety of plant growth and development progresses. Ethylene was also shown to mediate plant responses to abiotic-and biotic-stress. Ethylene-regulated growth and development progresses include seed germination, growth, flowering, leaf senescence, fruit ripening, stomatal movement, programmed cell death. In addition, ethylene is involved in plant responses to drought, waterflooding and pathogens invasion. Besides the mediation of growth and development and stress response described above, ethylene may play role during adventitious root formation in plant.Although a large number of works have studied the effect of ethylene on adventitious root formation, the results remains unclear due to the difference of plant species, experiment condition or the applying concentration of ethylene and ethrel. Even in same species, such as mung bean, conclusion is still inconsistent. Therefore, whether ethylene regulates adventitious root formation is still an open question. NO is an important messenger molecule in plant. Studies show that NO mediates various plant physiology progress, such as seed germination, the growth of root system, flowering, stomatal movement, pollen germination and tube growth and stress response. Previous study in our experiment show that NO participate in adventitious root formation of hypocotyls cutting in mung bean. However, the relationship between ethylene and NO is still unknown during adventitious root formation.In the present study, the hypocotyl cuttings of mung bean were used as materials, thesis described above was investigated by pharmacological approach, laser-scanning confocal microscopy and gas chromatograph. The results were as follows:1Ethylene releasing compound ethrel at the concentration between5-30μmol/L could promote adventitious root formation effectively and ethrel at the concentration of10μmol/L had the best promoting effect. Ethylene biosynthesis precursor ACC at the concentration between10-50μmol/L, only10μmol/L ACC could promote adventitious root formation effectively.2Ethylene biosynthesis inhibitors AOA (1-20μmol/L)、CoCl2(20-50μmol/L) and ethylene action inhibitors DDC (100-500μmol/L)、AgNO3(10-30μmol/L)、1-MCP (1-10μl/L) could inhibit adventitious root formation effectively. AOA at the concentration of (10μmol/L、CoCl2at the concentration of (30μmol/L)、DDC at the concentration of (300μmol/L)、AgNO3at the concentration of (15μmol/L)、1-MCP at the co concentration of (5μl/L) had the best inhibiting effect. And at these concentrations, adventitious root number is the half of the control. So we used these concentrations in the following experiments.3Ethylene (10μmol/L) and ACC (10μmol/L) could reverse the inhibiting effect of ethylene biosynthesis inhibitor AOA (10μmol/L)、CoCl2(30μmol/L) but could not reverse the inhibiting effect of ethylene action inhibitor DDC (300μmol/L)、AgNO3(15μmol/L)、1-MCP (5μl/L)4Ethylene biosynthesis inhibitor AOA (10μmol/L) could inhibit ethylene production significantly, but ethylene action inhibitor1-MCP (5μl/L) had no effect on ethylene production.5SNP (300μmol/L) could effectively reverse the inhibiting effect of ethylene biosynthesis inhibitor AOA (10μmol/L)、CoCl2(30μmol/L) and ethylene action inhibitor DDC (300μmol/L)、AgNO3(15μmol/L)、1-MCP (5μl/L).6From NO fluorescence images it could be seen that ethylene biosynthesis inhibitor AOA(10μmol/L) and ethylene action inhibitor1-MCP (5μl/L) could prevent the production of NO in the base of hypocotyl cuttings.Altogether, these data show that ethylene plays an impotent role during adventitious root generation, and NO mediated ethylene-induced adventitious root generation.